We cannot solve problems with the kind of thinking we employed when we came up with them." Albert Einstein "Stay away from those people who try to disparage your ambitions. Small minds will always do that, but great minds will give you a feeling that you can become great too." Mark Twain "I never dreamed about success. I worked for it." Estée Lauder "The pessimist sees difficulty in every opportunity. The optimist sees opportunity in every difficulty." Winston Churchill "If you're not positive energy, you're negative energy."

WAQUARUDDIN SIDDIQUI, Fatima ALMETWALI and Jawad FAYEK, who made this time joyful but always efficient. I am extremely grateful to my parents for their love, prayers, caring and sacrifices for educating me and preparing me for my future. A special feeling of gratitude to my loving sisters Ekhlass and Nour. I am very thankful to my fiancé Hussein RAAD for his understanding and continuing support to complete this research work.

Table of contents :

List of Abbreviations:

General Introduction

Most of the energy produced is derived from finite resources, which not enough to keep up as the consumption speed is increasing. Demand for energy is growing as populations increase. Global energy consumption is increasing in an average of 1 % to 2 % per year. The main source of energy we use comes from non-renewable resources for most countries. Most non-renewable energy comes from fossil fuels such as petroleum, crude oil, coal, natural gas, and nuclear fuel since there is a finite uranium supply in the world. Currently, there is a depletion of non-renewable resources that may let them nonexistent in future generations. However, many European countries still depend heavily on fossil fuel. Hence, it was possible to estimate that by 2050, only 14 % of oil proven reserve, 18 % of gas proven reserve and 72 % of coal proven reserve will remain. 1 Fossil fuels are not only limited but also, they are harmful at the same time. They release carbon dioxide when heated, which disrupt the balance of gases on earth and making them responsible for global warming and other environmental problems such as air pollution. Therefore, the transition to renewable and clean energy is required to avoid the complete depletion of fossil fuels and to minimize the environmental and health impacts.

Renewable energy is derived from natural sources that are recharged in higher speed that they are consumed. Sunlight and wind are examples of renewable sources. Generating renewable energy releases lowers emissions that non-renewable sources. Hence, green growth of energy has become a famous term among researchers. Solar energy is the most profuse of all energy resources, where sun provides the most abundant energy to earth. Solar technologies can create heat, cooling, lightening and electricity from sunlight. Solar cell is one of the solar technologies that have attracted the attention as a key device to convert light energy into electrical energy by electrochemical reaction (photovoltaic effect). 2 Another attractive green renewable energy is thermal energy or thermoelectricity. Converting thermal energy into electricity occurs using thermoelectric generator. 3 Thermoelectric device employs waste heat to produce power. Thus, it can be considered as eco-friendly energy source. From economic side, sunlight is free and waste heat is a free source generated by human body, automobile engines and industries, which makes them suitable techniques through the energy and environmental crises.

Since the creation of solar cells and thermoelectric materials, they can be classified into two generations: inorganic that is the traditional one and organic generation. Traditional devices are based on their manufacturing on inorganic materials as semiconductors for creating electricity.

The highest solar cell efficiency is approaching 29-30% based on undoped crystalline silicon 4 and it reached 32.5% using a combination of multiple perovskite with multiples of silicon. 5 However, the best thermoelectric performance were noticed for devices based on inorganic materials. 6,7 On the other hand, devices based on inorganic materials require high power consumption and require complicated processing technique and expensive materials, that make them limited for application in sensing devices. Moreover, inorganic materials are expensive and toxic specially for bio-used applications. The undesirable in most inorganic compounds cannot be removed by oxidation or thermal decomposition. Therefore, replacing inorganic semiconductors with organic counterpart is a need. Organic semiconductors are made up of polymers and π-bonded molecules based on carbon and hydrogen atoms and may include heteroatoms such as nitrogen, sulfur and oxygen. In principle, they are insulators but conduct when charge carriers are injected by certain methods such as doping and photoexcitation. One of the main advantages of organic semiconductors is flexibility. They are generally synthesized via chemical methods with easier conditions allowing them to be with higher potential applications for flexible electronic systems. In addition, they are of low weight and low cost, which make them economically attractive. Solubility of organic semiconductors is another interesting parameter, which could be controlled by incorporation of functional groups to facilitate the film processing in devices manufacturing. Moreover, organic semiconductors as conjugated polymers are with unique properties as the possibility of having high average molar mass, better flexibility through the molecular chain and mechanical flexibility that is suitable for large-area industrial applications. [START_REF][END_REF] A remarkable progress has been made in their different applications since their first report in 1940s. 9 Conjugated polymers are used in light-emitting field-effect transistors OLED, organic field-effect transistor OFET, organic thermoelectric OTHE, and organic solar Cells OSCs.

The enhancement of the properties of conjugated polymers can be performed by varying the electronic structure. Small modifications of the chemical structure can have a large effect on the electrical and optical properties of the organic semiconductor. 10 Applying functionalization strategies is a strategy to increase the solubility and the charge carrier mobility. In addition, molecular organization is one of the methods to increase aggregation and specify the chain orientation.

Therefore, the aim of this PhD project is to develop new conjugated polymers as organic semiconductors to be used in solar cells and thermoelectric materials for enhanced performance. To maintain this objective, we will have a literature review followed by applying practical strategies such as functionalization strategies to improve the current properties. This manuscript is composed of three chapters. The first chapter is an introduction to conjugated polymers and their electric and optoelectronic properties. The second chapter focuses on organic solar cells and the development of new metallooligomers based on diketopyrrolopyrroles DPP as donor materials for achieving high power conversion efficiencies. The third chapter is introducing thermoelectric materials and developing new ntype conjugated polymers to be used as conducting polymer after doping in thermoelectric materials or to be integrated in organic field effect transistors without doping. Then, the main results will be presented in general conclusion of the manuscript.

Chapter I

Chapter 1

I.

Conjugated Polymers:

1.

Introduction/general definition:

In 2000, Heeger, MacDiarmid, and Shirakawa were awarded a Nobel Prize granted the discovery of conducting polymers after their work on polyacetylene PA (Figure 2), which is a long carbon chain, and each carbon is bound to two neighboring different carbons and one hydrogen atom. This polymer was first synthesized in 1958 within the group of Giulio Natta, but its semiconducting properties were not studied at this stage. 11 In 1970 more studies were carried by the group of Heidi Shirakawa to study the polymerization and the polymer shape by making films for spectroscopic studies. 12 They demonstrated that the electrical conductivity of Trans-PA could reach 105 S cm -1 which started the interest for using organic materials in electronic devices. 13 The ability of PA to be conductive is related to the fact that it is a conjugated polymer. Conjugated polymers are characterized by a carbon backbone made up of alternative single and double bonds. Conjugated polymers have delocalized π-electrons due to the overlapping p-orbitals. 14 For better understanding of conjugation (C=C), ethylene is the simplest organic molecule with a double bond to be explained. Each carbon in the ethylene molecule has three sp2 orbitals and one pz orbital. The overlapping of the two sp2 orbitals form the σ bond, while the overlapping of pz can be overlapped in-phase (similar lobes of pz orbital overlap) or out of phase. The two different types of overlapping lead to the formation of bonding and antibonding molecular orbitals (MOs), where the bonding molecular bonding (π) is highly stable compared to the anti-bonding molecular orbitals (π*) (Figure 1). Upon energy supply, electrons can jump from π to π*. For organic molecules with more than two carbons, such as butadiene there is an alternation of double and single bonds. A molecule with separation of double bonds by a single bond is called "conjugated" molecule. [START_REF] Clayden | Organic Chemistry[END_REF] The mechanism of electron transfer in conjugated polymers has been explained based on polyacetylene. The single and double bonds existed in the conjugated system contain a localized sigma bond that favors the strong chemical bond. Besides, the double bond carries a delocalized π-bond that is weaker than that of the sigma bond. [START_REF] Ravichandran | [END_REF][START_REF] Wise | Electrical and Optical Polymer Systems: Fundamentals, Methods, and Applications[END_REF] The overlap between the pz-orbitals of π bonds allow their electrons to move freely through the system.

Figure 2: The conjugated π-system un cis-polyacetylene Conjugated compounds can be linear or cyclic. At the beginning of 1980s, aromatic molecules were still used as conducting materials due to the instability of polyacetylene PA. It is related to the sensitivity towards oxygen. Due to the fact that oxidative attack on the polymer backbone happens simultaneously and with long term exposure or upon high temperature, the concentration of oxygen as dopant decreases through intramolecular regrouping of hydrogen atoms leading to the formation of hydroxyl groups and more polymer degradation. [START_REF] Will | [END_REF] Polyparaphenylene PPy is another well studied conjugated polymer that shows a better thermal stability. 19,20 However, due to the low solubility and difficulties in the reproducibility of PPy, alkyl substituents PPy-1 was introduced to enhance the solubility 21 but it led to more rotation than polymers without alkyl substituents and then it affected the conjugation. Other well-known conjugated polymers are poly(phenylene vinylene) PPV, and polythiophene PT (Figure 3).

Figure 3:

The main families of studied conjugated polymers 11,13,19,20,21 2. Electronic structure :

Electronic structure of atoms and molecules is the series of energy levels that it is possible for a bound electron to occupy that is not allowed to leave its orbit.

In conjugated molecules, there are more than one bonding and one anti-bonding molecular orbitals leading to different orbitals termed by Ψ. Upon energy supply the electron transfer from the bonding molecular orbital that is less stable, which is termed as highest energy occupied molecular level (HOMO) to the most stable anti-bonding molecular orbital that is termed as lowest energy unoccupied molecular orbital (LUMO) (Figure 4).

Figure 4: The different bonding and anti-bonding molecular orbitals in butadiene

The length of a molecule can be increased by joining another similar molecule to it. For example, 1,3-butadiene can be formed by joining two ethylene. Hence, the butadiene has two π-π* pairs, which the identical copies are degenerated, and the two levels are split into four.

By increasing the length of the conjugated molecule, more π and π* are added. This allows a decrease in the gap between the highest π and the lowest π* level. These frontier orbitals correspond to the valence and conduction bands in conjugated polymers. Indeed, the increase in the conjugation length not only transform levels into bands, but also progressively decreases the band gap between the HOMO and LUMO levels allowing conjugated polymers to have a suitable low energy gap to be used as semi-conducting materials. It is noted in the literature that there is an impact of the extension of the πconjugation length either in the bond length or in the length in the polymer chain on the value of the band gap (Figure 5). As the number of monomer units increases, the number of πelectrons increases which leads to a greater number of overlapped atomic orbitals. The number of bonding and anti-bonding molecular orbitals increases along the width of the energy band consequently a smaller gap between the HOMO and LUMO levels. Energy band theory allows explaining the differences between insulators, semiconductors and conductors. The band gap in a highly conjugated system is the energy difference between the valence and the conduction band in the material. This formation of bands is a feature of valence electron in the atom, with high conjugation length, the energy levels of the atoms which contain the valence electrons is called the valence band. Conduction band is the band of electron orbitals that electrons can jump up into from the valence band when excited. The energy band gap corresponds to the energy required to promote a valence electron to become a conduction electron. The band gap can be calculated by the energy difference between them.

It corresponds to the difference between the ionization potential (IP) and the affinity potential (AP). IP is the minimum energy required to remove the most loosely bound electron of the molecule, whereas AP is the minimum energy to capture an electron (Figure 6).

Figure 6: The electron affinity and ionization potential in organic semiconductors

Moreover, the HOMO and LUMO levels depend on the composition of the aromatic units of the monomer not only the length of the conjugated system. The presence of strong donor group leads to increase in the HOMO energy level and consequently an increase in the ionization potential. Hence, the conjugated polymer is considered as donor material that is easily can be oxidized. On the other hand, the presence of strong acceptors leads to decrease in the LUMO energy level and then increase in the electron affinity and then the conjugated polymer will be considered as acceptor material, which can easily be reduced.

In order to evaluate the EHOMO and ELUMO we use the cyclic voltammetry diagram. It is a very suitable method for a range of applications. It is a standard technique for characterizations. HOMO represents the energy needed to extract an electron that is an oxidation process, and LUMO represents the energy needed to inject an electron to the molecule that is a reduction process. Cyclic voltammetry measures these processes through measuring the redox potential Ered and Eox. Ferrocene is utilized as a reference to calculate the HOMO and LUMO energies according the following equations with -4.4 eV the ferrocene value. [START_REF]HR-MS (ASAP+) m/z [M + • ] calcld. for C18H9O3F21S = 703[END_REF] E HOMO = -e [Eox onset + 4.4] (1) E LUMO = -e [Ered onset + 4.4] (2) Wherefore, two types of conjugated polymers can be differentiated according to the composition of the monomer unit. Polymer with monomer of donor nature is considered as p-type conjugated polymer with hole mobility semiconductor after oxidation of the polymer through p-doping process. While monomer with acceptor nature is considered as n-type conjugated polymer with electron mobility semiconductor after the reduction of the polymer through n-doping process.

For a very large band gap (more than 2 eV) the material is classified as an insulator. When the conduction band overlaps the valence band then the band gap is zero the materials are classified as conductors (Figure 7). In this thesis, we are more interested in semiconductor materials that can conduct electricity upon excitation due to the presence of a small band gap (non-zero less than 2 eV). 25 Organic conjugated polymers aren't well explained via the energy band theory. Hence, their charge transport mechanism is studied from theoretical and experimental views by a number of researchers. 26,27 Figure 7: Difference of energy levels among metals, semiconductors and insulators Therefore, the band gap is strongly related an effected to the chemical structure and the morphology of polymer. Hence, there are a variety of parameters affecting the properties of conjugated polymer as the optical, electronic and optoelectronic properties.

Main properties of Conjugated polymers:

Since the discovery of conjugated polymers, they have received increasing attention owing to their properties: optical, electronic and optoelectronic properties. 25 André-Jean Attias, Technique de l'ingenieur, E1862 V2, 2017. 26 Optical properties:

These properties are more related to the optical excitations and transitions between HOMO and LUMO levels based on the mechanical effect of light on electronic materials, especially organic semiconductors in organic solar cells.

Optical properties such absorption, transmittance and dispersion represent the behavior of the conjugated polymer with light. The particular optical absorption of a conjugated polymer is critical to the performance of the optoelectronic device. 28 The absorption represents the phenomenon by which the energy of a photon is converted to internal energy taken by another particle, for example an electron.

The amount of energy carried by photon depends on its wavelength. The shorter the wavelength of light, the higher the energy.

Absorption spectroscopy is a way to study the energy levels of atoms, molecules and polymers. The spectrum of a molecule or a polymer depends on its energy-level structure. The minimum energy difference allowing a photon to be absorbed is called optical band gap Eg opt . Conjugated polymers owe similar electronic band gap as conventional semiconductors with electron-electron and electron-hole coupling. 29 The π electron from the ground state (HOMO) after excitation can absorb a photon and jump to the excited state π* (LUMO), forming a positive charge behind. These holes formed are bonded to electrons by Coulomb interaction forming an exciton (neutral quasiparticle) and then this attraction allow the formation of exciton band below the conduction band threshold. The difference between the HOMO level and exciton band is named optical band (Eopt) with exciton binding energy (Eb= Eg-Eopt) with average range 0.5-1.0 eV for many conjugated polymers (Figure 8). The Eg opt can be calculated from a UV-Vis spectroscopy absorption spectrum, according to the following equation:

Where, h is the Plank constant, c is the speed of light in vacuum, and 𝝀abs (onset) is the wavelength of the less energetic photon absorbed from the absorption spectrum (Figure 9). The first mechanism is absorption (10 -15 s) of photons by a molecule. It causes electrons from the fundamental state (S0 on figure 10) to reach higher energetic states (S1 on figure 10). Then, there are two possible radiative pathways for electron to go back to its fundamental state: Fluorescence and Phosphorescence and two non-radiative pathways: intersystem crossing and internal conversion.

Fluorescence (10 -9 s to 10 -7 s) is the emission of photons with radiative transition from S1 to S0. Internal conversion is non-radiative transition between two electronic states of the same spin multiplicity. It proceeds rapidly on a timescale (10 -11 s to 10 -9 s) between two singlet excited states.

An alternative transition to fluorescence and internal conversion is intersystem crossing from S1 to the T1 state. It is a non-radiative transition between two isoenergetic vibrational levels belonging to electronic state of different spin multiplicity. After intersystem crossing the molecule directly undergo vibrational relaxation toward the ground vibrational level T1. This non-radiative decay mechanism from S1 to T1 reduces the luminescence. Phosphorescence (10 2 to 10 -4 s) is the second radiative pathway for electron between two electronic states of different spin multiplicity. It is the transition from T1 to S0. Conjugated polymers with optical properties could be used in two main fields: light generation and light harvesting. In light generation field, there are important applications includes polymer light emitting diodes and lasers. As light harvesting materials, they are mainly used in solar cells, where electrons need to be collected before returning to their fundamental state. 32

3.2.

Electronic and optoelectronic properties:

In this paragraph we will explain the methods of charge creation in a conjugated polymer and their electronic and optoelectronic properties, which are a set of parameters that describe the state and the behavior of electrons in the material.

Charge generation:

The charge generation can be created by different mechanisms depending on the type of excitation. First, it can be the formation of exciton (dissociated electron/hole pair) under light as previously described. After the absorption of a photon, and the formation of exciton, an electron can reach the conduction band if recombination is hindered. This property is utilized in organic solar cells based on conjugated polymers as explained in the optoelectronic properties paragraph.

Second, the charge carrier creation also can be through the formation of a polaron. Polarons form due to the coupling of excess electrons or holes with a local polarization field. A polaron can be radical cation or radical anion in the case of p-or n-chemical doping, respectively. These polarons are responsible for conductivity (Figure 11) that is explained in the next paragraph.

Figure 11: The different ways of charge generation in conducting polymers

Doping represents the oxidation and reduction reactions in conjugated polymers that induce conductivity. Molecular doping is applied in the field of organic electronics. 33 The performance of a doped conjugated polymer strongly influenced by the type of dopant and its distribution. In organic electronics, the most dopants for conjugated polymers are molecules with different energy levels from the host polymers. It is classified as p-doping and n-doping (Figure 12).

Figure 12: The different mechanisms in p-type and n-type doping 34

P-doping is a way to introduce charges to the semiconducting polymer. This process involves an electron transfer between the semiconducting polymer and a small molecule. There are a broad variety of p-type dopant, such as 2,3,5,6-tetrafluoro-7,7,8,8tetracyanoquinodimethane (F4TCNQ), which has electron affinity (EA= 5.2 eV) to easily oxidize polymers like poly(3-hexyl thiophene). 1,3,4,5,7,8-hexafluoro-tetracyano-naphthoquinodimethane (F6TCNNQ) with EA= 5.3 eV and hexacyano-tri-methylene-cyclopropane with EA= 5.9 eV are other examples of p-dopants with high electron affinity (Figure 13). 35 We are more interested in n-doping for n-type conjugated polymers, where the conductivities are mainly below 10 S cm -1 and the thermoelectric power factor not more than 10 µWm -1 K -2 . 36 N-doping of conjugated polymers is when the dopant plays the role of donor, so it donates electron to the LUMO level of the n-type conjugated polymer. As examples of dopants are the small atoms as alkali metals such as Lithium, cesium and Lewis acids. However, small molecule are dopants able to diffuse and then lead to device instability. Therefore, using large and aromatic molecules as donor is more efficient in preparation of stable device to not diffuse in the thin film, but the size must not be too large to not act as a trap, where they have to be allowed to inject an electron to the LUMO level of the conjugated polymer. Hence, the HOMO level must lie above the LUMO of the matrix. 37 This type of doping is still complicated due to the limited molecules combining the stability with appropriate high LUMO state compared to the organic conjugated polymers because the stability of the dopant against oxidation decreases as the HOMO level increases The increased doping level is coherent with enhanced electrical conductivity. For example, the conductivity of Polythieno [3,4-b]thiophene PTbT (Figure 14) homo polymer is increased from 10 -5 S cm -1 in the neutral state to 0.2 < S cm -1 in the doped state. In the same study, it has been demonstrated that morphological features and aggregation could impose an impact on the electrical conductivity. 39

Electronic properties:

There are two main electronic properties which determine the behavior of conjugated polymers: the charge mobility and the electrical conductivity.

Charge mobility in semiconductors:

The charge mobility refers to how quickly electrons and holes (in n-type and p-type materials, respectively) can be displaced under the application of an electric field. It is influenced by various structural parameters such as the chemical structure or the molecular arrangement of the conjugated polymer but also by its average molar mass.

Charge mobility can be explained by polaron delocalization. There are two types of polaron delocalization after its generation: intrachain and interchain (Figure 15). The interchain polaron propagation arises from two different polymer chains or one folded single chain. 40 The intramolecular mobility is highly sensitive to the chemical structure of polymer chain. 41 It is related to the charge movement within a polymer chain. Intermolecular mobility is when charges are able to delocalize and move along chains. The arrangement of the transport path plays an important role in governing mobility, where charges are confined to the ordered region compared to the amorphous polymer. 42 Note that ordered or crystallinelike regions are polymer chains arranged in a regular manner. In polymers, crystalline regions are based upon long-chain molecules and usually they are entangled with amorphous regions. 43 Interchain hopping is another term that explains the charge mobility in molecular solids in an electric field period within disordered regions.

Figure 15: Mechanism of intra chain and interchain delocalization of a polaron

Indeed, it has been shown that high average molar mass polymers lead to larger mobilities. The average hole mobility for example, is improved by two orders of magnitude from 2x10 -3 to 0.15 cm -2 V 1 s -1 ,when the average molar mass is doubled from 30.1 to 61.8 kg/mol. 44 In the case of one of DPP based polymer (DPP-DTT), (Figure 16) extremely high average molar mass of 110 kg.mol -1 led to very high mobility around 8 cm -2 V 1 s -1 with maximum of 10.5 cm -2 V 1 s -1 , while with average molar mass of 29 kg.mol -1 the mobility is around 1 cm -2 V 1 s -1 . 45 Figure 16: The structure of DPP-DTT polymer An explanation for the relation between high molecular weight and mobility is that the ordered regions are more interconnected by longer chains with a higher degree of molecular ordering. This improves the interchain charge hopping resulting with facilitated charge carrier transport in disordered regions. 46 However, in a study by Takimiya et al there is no impact of increasing the average molar mass on the carrier mobility with increasing the average molar mass from 12 to 46 Kg.mol -1 . 47 N-type conjugated polymers can even exhibit higher electron mobility due to the higher crystallinity obtained with lower average molar mass. 48 Hence, increasing the average molar mass of conjugated polymers increases charge mobility in both n-type and p-type conjugated polymers.

Semiconducting conjugated polymers with high charge mobility are widely used in organic field effect transistors (OFETs). OFET is a voltage-controlled three terminal device. One of its basic components is semiconductor layer. Inorganic semiconductors are replaced by conjugated polymers. Both p-and n-type OFETs are required for organic electronics. Thus, por n-type conjugated polymers are used depending on the type of OFET device. They are promising candidates for OFETs since they offer unique advantages compared with traditional silicon electronics, including mechanical flexibility, solution processability and tunable optoelectronic properties. 49

Electrical conductivity of conducting conjugated polymers:

The conductivity of a material depends on the concentration of free electrons in it. It is determined by the carrier mobility (μ) and the doping level (n) with σ =n e μ, where n is the density of charge carrier and μ is the carrier mobility and e is the carrier charge that is constant. Therefore, the electrical conductivity is affected by the charge transport and the doping process. 50

Optoelectronic properties:

In organic solar cells (OSCs) the recombination of photogenerated charge carriers is the most important loss mechanism. Thus, limiting the recombination losses is considered as a key strategy to enhance efficiencies. In OSCs recombination can occur at different stages during photocurrent generation. After absorption, organic semiconductors strongly bound exciton. This exciton can move through diffusion and split at the Donor-Acceptor interface by charge transfer. But, if exciton does not reach the interface during its lifetime, exciton recombination occurs. [START_REF] Wilken | Charge Recombination in Organic Solar Cells[END_REF]

II.

Main strategies to improve the properties of organic conjugated polymers:

Conjugated polymers have attracted the attention due to the ability to tune the band gap and the position of HOMO and LUMO levels by designing the molecule structure. Small modification of the chemical structure can have a large effect on the properties of these organic semiconductors. 52 Several strategies can be applied to enhance the physical properties of conjugated polymers for improved efficiencies of organic electronic devices, starting with the choice of the type of the conjugated polymers destined. Then, looking to decrease the band gap mostly for organic solar cells. Then, to improve the solubility of the synthesized conjugated polymer and finally to increase the π-π aggregation and to control the chain orientation depending on the application.

The choice of monomer units/P-type and n-type CP:

The choice of the conjugated polymer backbone depends on the targeted application of the desired conjugated material. For the synthesis of n-type conjugated polymer, it is crucial to decrease the affinity potential (AP) to obtain a high HOMO level. Hence, it is crucial to use acceptors blocks in the monomer unit. Therefore, creating strong acceptor units is essential in the synthesis of low-band gap conjugated polymers. Nowadays, a big number of strong acceptor units have been reported in the literature, such as naphthalenedicarboximide (NDI) N-1, 53 diketopyrrolopyrrole (DPP) N-2, 54 and benzothiadiazole (BTz)N-3 55,56 Polyisothianaphthene (PITN) (Figure 23) was the first polymer with a small band gap. The repeating unit of this polymer consists of bicyclic quinoid structure of high electrondonating ability. This makes the polymer with high HOMO level (around -4.88 eV), which makes them suffer from oxidation under ambient conditions. Analogues of ITN with high electron deficiency have been developed such as thieno (3,4-b)pyrazine (TP), thieno (3,4b)(1,2,5)thiadiazole (TTz), Thienoisoindoledione (TID), thieno (3,4-b)thiophene with ester group (TbT) and benzo(2,1,3)thiadiazole(BTz), [START_REF] Mikie | [END_REF] simple bithiazole and thiazolothiiazole. 58 And benzodithiophenedione BDTD 59 (Figure 18).

Figure 18: Chemical structures of electron-deficient thiophene based units (A)

All these units have been incorporated into π-conjugated polymers to obtain small band gap with oxidative stability, where careful selection of donor and acceptor units allows modulation of the band gap as well as the HOMO and LUMO energy levels.

Concerning the synthesis of p-type conjugated polymers, it is required to have high ionization potential (IP). Therefore, it is required to use donor blocks in the monomer structure to decrease the LUMO level.

Various donor units have also been used in the formation of D-A conjugated polymers, such as thiophene T, selenophene S, bithiophene BT, bibenzothiophene BBT, thiophenethiopheneTT, thiophene Vinylthiophene TVT, cyclopentene dithiophene CDT, 60 phenyl Fluorene derivatives F-1, F-2 and carbazole derivatives C-1 and C-2 with the structures depicted on Figure 19. 61,62 Figure 19: Structure of common donor units These donor units are used in building p-type conjugated polymers. The performance of p-type semiconducting polymers has achieved much progress. There still exist several challenges for n-type semiconducting polymers. Obtaining conjugated polymer with a small ban gap is one of the effective approaches to enhance their performance.

Decreasing the band gap energy:

Decreasing the band gap energy in the absorption range is required for organic solar cells applications since with smaller band gap more photons can be absorbed, less energetic photons will be able to generate excitons. Another advantage of a small band gap is the reduction of the energy loss. The energy loss in organic solar cells is attributed to the charge transfer, separation and transport. Small band gap could reduce the energy loss by enhancing the diffusion of exciton and reducing its recombination during charge diverse pathways.

Various strategies have been developed to obtain a narrower band gap, such as using heterocycle, increasing the planarity, stabilizing the aromatic resonance or applying the donor-acceptor approach.

Using of heterocycle:

Introducing heteroatoms by using heterocycles in the monomer units leads to less aromatic structures due to the electronegativity of the heteroatom. These cycles are energetically less stable as the resonance energy decreases, which favors smaller band gap (Figure 20). 63

Figure 20: Resonance energy of benzene and heterocycles

Among the number of π-conjugated polymers, polythiophenes (PTs) are widely studied and they have reached industrial utilization in light emitting diodes and organic transistors. 64 It has been confirmed that the increase in the number of thiophene repeating units leads to a smaller band gap. 65 It was found that the 2,5-coupled polythiophene PT is highly conductive with thermal stability but insoluble. Flexible side chains were added to enhance the solubility. Poly(3alkylthiophene)s (P3ATs) were synthesized with the same method as 2,5-coupled polythiophenes in the late 1980. 66,67 However, random couplings in P3AT were created using chemical and electrochemical couplings. Regio isomeric, regioregular and regioirregular couplings were obtained with only 50-80 % head-tail (HT) couplings, hence not enough rigidity of the conjugated polymer backbone. This led to an increased band gap energy (Figure 21).

Increasing the quinoid form stabilization:

One of the most important parameters to consider is the stability of the resonance structures to maintain a small band gap. In this field, there are two main forms: the aromatic form and the quinoid form (Figure 22), which is obtained by the delocalization of π-electrons. Normally, due to the delocalization of π-electrons and the breakdown of aromaticity the quinoid form is energetically less stable than the aromatic form but it allows obtaining polymers of smaller band gap. 68 Figure 22: Aromatic and quinoid forms of some conjugated polymers 10 Polypyrrole and polythiophene were synthesized with band gaps of 3.2 eV and 2.0 eV, respectively. 69,70 More work was done for polythiophene to obtain a smaller band gap. The addition of one benzene ring is one of the methods, which is followed for a further decrease of the band gap. Polyisothianaphthene PITN is a result of this strategy that shows a decrease in the band gap to 1 eV with a favored quinoid form (Figure 23). More benzene units were added to study the effect of the number of benzene units on the band gap value so PITN-1 and PITN-2 were synthesized. However, these supplementary units didn't allow a smaller band gap due to the disfavored quinoid form. 71 More polythiophene derivatives were synthesized in the last decades with quinoid form since one of the most efficient approaches is to tailor the monomer structure to increase the quinoid structure. Poly-(thieno(3,4-b) pyrazine) PTP has been synthesized with one of the lowest band gaps of 0.95 eV because of the planar quinoid form (Figure 23). 72

Increasing the planarity:

It is crucial to keep a good planarity of the conjugated polymer backbone to maintain the conjugation with no disruption due to the bond rotation and steric hindrance. Developing highly planar semiconducting polymers is a basic property for achieving a good mobility. Planar conformation extends the π-conjugation length and π-electron delocalization. Moreover, it leads to strong solid-state π-π stacking between chains and then a narrow band gap. 73,74

By covalent bond formation :

Planarity with covalent bond formation can be in a form of double bonds or in ladder structure as in figure 24. Ladder conjugated polymers are conjugated polymers with good planarity due to the presence of an uninterrupted sequence of adjacent rings sharing two or more atoms. 75 In this type of polymers, the restricted torsional motion of the backbone extends the carrier delocalization and prevents the conformation disorder. This will encourage the charge transfer, interchain interactions and thermal stability. 76 Hence, the synthesis of polycyclic PC compound of fluorene type (standard backbone in figure 25) has been widely studied. Using alkyl or alkoxy substituents to position 9 is one of the promising strategies to improve both the solubility and the rigidity of the polymer. 77

Figure 25: Standard backbone of fluorene

There are a variety of polycyclic compounds of fluorene with different length of the repeating unit that affect the rigidity and the electronic band gap with a strong bathochromic shift between PC-1 and PC-2 (Figure 26). 78

Figure 26: Structure of polyfluorene derivatives

Another way to obtain a rigid conformation is the utilization of polycyclic hydrocarbons PAHs. These hydrocarbons include phenanthrene, the triphenylene and Pyrene with benzoic positions, which permit easy functionalization (Figure 27).

Figure 27: Structure of some polycyclic hydrocarbon

As a method to obtain a rigid and planar confirmation was the insertion of methyl bridge between thiophene units. Synthesis of PT-1 (Figure 28) clearly demonstrates that rigidification constitutes is an efficient strategy to reduce the HOMO-LUMO gap. The resulting band gap is 1.65 eV. 79 Other modifications were carried on position 3 and 4 of thiophene 77 X. While focusing on achieving a coplanar conformation, the π-interactions among the aromatic units lead to a decrease in the solubility of the conjugated polymers. Therefore, some modifications were carried, such as the addition of alkyl groups to phenanthrene PAH-1 and Pyrene PAH-2 and phenyl groups to triphenylene PAH-3 (Figure 29). Number of derivatives were obtained using different R substituents followed by the study of their effects on the optical properties of the obtained polymers. However, the UV-Vis spectrum of PAH-2 is blue shifted due to the alkoxy groups on poly(arylene) backbone that increase the dihedral angle of consecutive aromatic rings and lead to less electronic conjugation. It is concluded that higher number of aryl units is favored since the polymer is of less capability to aggregate and the extra arylene units between triphenylene repeating unit reduce the twist in the polymer backbone and hence obtaining a well-organized structure. 81,82

Figure 29: Polycyclic hydrocarbon derivatives

Taking fluorene molecule as standard, the introduction of a heteroatom to rigid backbone is interesting to be explored as a combination of the presence of planarity and a heteroatom for obtaining a smaller band gap. The introduction of nitrogen atom allows the synthesis of carbazole aromatic character due to the lone pair of the nitrogen atom (Figure 30). 83 Moreover, the presence of a heteroatom facilitates the functionalization of the monomer unit and consequently the modification of the chemical and physical properties. Benzosilols are compounds with silicon as hetero atom. The first synthesis of 9,9diphenylsilafluorene (Figure 31) was done in 1955. 84 The utilization of silafluorene derivatives has gained much attention in the synthesis of copolymer and a series of copolymers were synthesized. 85 This family of conjugated polymers is of interesting optoelectronic properties of organic solar cells and as blue emitters in polymer light emitting diodes. The rigidity of the synthesized polymer can also be controlled by the presence of intramolecular interactions through utilization of heteroatoms. Some features of conjugated polymers are shown in figure 32.

Figure 32: Types of conjugation system in conjugated polymers

Introducing noncovalent interactions into the backbone of conjugated polymers is one of the frequently used methods to achieve planarity. Non-covalent bonds are non-covalent interactions that do not involve the sharing of electrons. There are a wide variety of examples in different fields as supramolecular chemistry. 86 Non-covalent bonds include hydrogen bonds, coordinative interactions and sulfur bonds. Normally, non-covalent bonds are weaker than covalent bonds by one or more in magnitude order. 87 The binding energies of noncovalent interactions cannot be neglected since they reach 4 KJ.mol -1 in certain molecules. Therefore, binding energies play an obvious role in serving extra binding energy that lock the coplanar conformation of conjugated polymers through minimizing its energy and increasing the torsional barrier of the conjugated polymer backbone (Figure 33). 88

Figure 33: Binding energies of noncovalent interactions in conjugated polymers

Hydrogen bonds are the most known non-covalent interactions. They are attractive forces between two permanent dipoles described as a special dipole-dipole forces. H-bonding has been represented by structural formulas A:H: B-type bonding elements, and it has been concluded that the H-bonding is largely ionic in character.

In 1997, a new family of poly(phenylenes) (pPYs) has been synthesized by the group of Moigne. Amino and esters groups were preinstalled on the same monomer to achieve planarity of the conjugated polymer backbone through hydrogen bonding as depicted in figure 33. 89 In 2013, a new n-type conjugated polymer benzodifurandione-based oligo(p-phenyl vinylene) (BDOPV) was synthesized. It contains nontraditional hydrogen bonds via electronegative carbonyl oxygen and aromatic unit. 90 In 2014, two new derivatives of poly(pphenylene vinylene) PPV, BDPPV and FBDPPV were synthesized which differ by the presence of fluorine atoms. Fluorine atoms can lower the LUMO level and lock the conformation of the conjugated polymer with nontraditional hydrogen bonds. Hence, these polymers show 87 P. shorter π-π stacking distance and enhanced rigidity, coplanarity and order of interchain packing (Figure 34). 91 Introducing intramolecular interactions results in a decrease of the band gap and in an increase in the charge transfer rate upon impacting the HOMO and LUMO levels. Therefore, high planarity of conjugated polymer backbone facilitates electron delocalization and π-π intermolecular interactions, which lead to a small band gap and fast charge transfer. 92 Among noncovalent interactions are coordinative interactions related to nitrogenboron interactions such as the classic chromophore boro-dipyrromethane (BODIPY). 94 Usually, conjugated polymers with this type of interactions have low LUMO level and small optical band gap. 95 In 2015, the group of Pammer worked on the synthesis of locked conjugated polymers starting from regioregular poly(pyridine) (PPY) equipped with 6-(1alkenyl) side chain following post functionalization strategy. 96 In 2016, group of Liu synthesized a new electron deficient conjugated polymer BNBP with fixed coplanar conformation due to N-B coordinative interactions. 97 Therefore, the planarity is maintained (Figure 36).

Figure 36: Locked conformation Conjugated polymers with N-B interactions

Due to the highly recommended properties of polythiophene derivatives and the usage of thiophene unit in a great variety of building blocks for polymer backbone, sulfur atoms play an obvious role not only as heteroatom but also in the conformation control of the conjugated polymers (Figure 37). 98 There are a wide number of non-covalent interactions between a sulfur atom and an electronegative atom as nitrogen, oxygen and fluorine, due to the partial donation of a lone pair of an electronegative atom to the 3d empty orbital of the sulfur atom. 99 thiophene is bridged with an oxyalkane unit. Its structure favors sulfur-oxygen interaction, which leads to a self-rigidification of the conjugated structure. 100,101 Figure 38: Sulfur-oxygen interaction in PEDOT Rigidification can lead to conjugated polymers with smaller band gap than poly(3alkylthiophenes). 102

New generation conjugated polymer via Donor-Acceptor Approach:

Insertion of electron withdrawing groups has a dominant effect that is the shift of LUMO away from the vacuum Level. However, the insertion of electron donating groups shifts the HOMO toward the vacuum level allowing high-lying highest occupied molecular orbitals (HOMO). This shift in HOMO level leads to easier oxidation of the polymer and then poor ambient stability. More efficient way is to reduce the lowest unoccupied molecular orbital (LUMO) and obtain a smaller band gap via incorporating strong acceptor unit. 102 Therefore, one of the most successful routes to decrease the band gap is to apply the donor-acceptor D-A approach. It was first carried by the group of Havinga. 103 It is based on a regular alternation of two units: electron rich donor (D) and electron poor acceptor (A) along the conjugation backbone. The band gap of the resulted polymer is calculated by the hybridization of the corresponding frontier orbitals of each of the donor and acceptor units. Due to the presence of a resonance form between the donor and acceptor units, the double bond character of the single covalent bonds increases. Hence, a reduction in bond length and then generation of new energy levels with increased HOMO level and decreased LUMO level with a smaller band gap (Figure 39). Introducing of an acceptor unit with different donor units give rise to a wide number of D-A conjugated polymers, the choice of the donor and acceptor units depends on the physical properties required of the desired polymer. We can distinguish three types of conjugated polymers: p-type, n-type and ambipolar conjugated polymers.

The PTB family synthesized by the group of Luping Yu. 105 It consists of alternating benzodithiophene (BDT) units as donor and TT as acceptor units (Figure 40), where a variety of substituents of donor and acceptor units were studied to optimize the properties of the polymer taking into consideration that the extension of the conjugation structure reduces the band gap. Obtaining a small band gap energy is essential in the synthesis of organic semiconductors. However, small band gap energy is not enough for better performance. Tuning the morphology of the conjugated polymer is a method to control the physical properties.

In this thesis, we are more interested in the donor-acceptor conjugated polymers due to their low band gap. As we demonstrated, achieving conjugated polymer with high electron mobility is not only related to low band gap and planarity of the system, but also to the molecular orientation and the average molar mass of the D-A polymers. The next paragraph will demonstrate how the morphology of the conjugated polymer and consequently the physical properties can be tuned by applying functionalization strategies such as side chain engineering.

Side chain engineering

Side chain engineering consists in making chemical modifications on the molecular structure of conjugated polymer. The role of the used side chain mostly for enhancing the solubility, increasing the π-π aggregation, controlling the chain orientation and improving the stability of the obtained polymer under ambient conditions.

To Increase Solubility:

As previously explained the charge carrier mobility is related to the average molar mass of the polymer. In most cases, the charge mobility increases as the average molar mass increase. The average molar mass of conjugated polymers depends on the chemical structure of the monomer, and the synthetic pathway. It is generally improved when the solubility of the monomers and of the growing polymer chain are good.

Side chain engineering is an efficient method to improve the solubility. In order to control the solubility of the polymer and for better processability, the side chains are introduced on the backbone. According to their chemical nature, the interactions with the solvents can be tuned, but they can also play a role on the polymer planarity and selforganization. Various flexible chains have been used as side chains for conjugated polymers such as: alkyl side chains, hybrid side chains, ionic side chains, oligoether side chains, fluoroalkyl side chains and latent reactive side chains (Figure 41). For the conjugated polymers in this thesis in order to improve the solubility, we will focus on three types of side chains: alkyl side chains, oligoether side chains, and fluoroalkyl side chains.

Alkyl side chains:

Alkyl side chains have been proven to play an effective role in intermolecular interactions and supramolecular self-assembly. They are directly attached to the conjugated polymers as solubilizing groups to enhance the solubility of the polymers in organic solvents. 107 The common types of used alkyl chains in conjugated polymers are linear and branched chains. Linear chains could be of different length as hexyl, octyl and dodecyl chains. 108 Linear chains with an even number of carbons are more familiar in conjugated polymers. It has been noticed that linear chain can favor interchain interdigitation. 109 The branched alkyl chains (Figure 42) reduce the interchain interdigitation and lower the polymer interactions due to their higher steric hindrance that can decrease the polymer planarity and then rise the π-stacking distance in the structure layer. 110 However, branched alkyl chains have a positive impact on the solubility of the conjugated polymer. 107 P3AT samples were synthesized with different linear alkyl side chains to study the impact of the alkyl chain on the solubility and consequently the average molar mass (Figure 43). As the length of the alkyl side chain increased from four (P3AT-R1) to twelve carbons (P3AT-R3), the average molar mass has been increased from 6.3 Kg.mol -1 to 22 Kg.mol -1 . But polymer with eight carbons alkyl chain (P3AT-R2) shows higher average molar mass of 35 kg.mol -1 due to higher degree of polymerization. The conjugated polymer with the higher average molar mass (P3AT-R2) exhibits average mobilities of 0.19 cm 2 V -1 s -1 that is almost double of P3AT-R1 (0.10 cm 2 V -1 s -1 ). 111

[T3(R)-il] polymers

The solubility of these polymers was measured. It is found to be around 2 mg/mL for the conjugated polymer with R1 linear chain. Better solubility was observed when the length of the alkyl chain increased to 12 carbon (R3) with 21 mg/mL. But, replacing the linear alkyl chain with branched chain (R4) results in the best solubility of 27 mg/mL. Hence, the solubility can be tuned by changing the length and the branching of the alkyl side chain. 112 Moreover, replacing linear alkyl chains by branched side chains does not only affect the solubility but also it can increase the π-stacking distance up to 0.5 Å and consequently reduces the hopping rate of the charge carrier along the packing direction. 113 However, a better crystallinity can be obtained when short branched chains are replaced with longer chains.

In the example of figure 45, the π-stacking distance of CDT-BTZ114 with R1 is about 3.5Å, it increased to 4.0 Å with R3 due to the steric hindrance. To study the effect of the change of the length and the type of the chain not only on the π-stacking distance but also on the molecular orientation of the conjugated polymers, a series of polymers (Figure 46) have been synthesized with different alkyl side chains.

Figure 46: Chemical structures of D-A conjugated polymers with different alkyl side

chains 115,116,117 In the presence of branched alkyl side chains, the aggregation of single polymer chains is poor, so they are more flexible and capable to interact with the surface by non-covalent bond (Van der Waals interactions) and then the polymer chains are ordered in face-on orientation. While, the edge-on orientation with linear alkyl side chains can be explained by the strong aggregation of the conjugated polymer prior to the polymer/ surface interactions.

To overwhelm the disadvantage of branched alkyl side chain on the polymer packing and to keep the solubility, researchers are applying a new strategy to shift the branching point away from the polymer backbone with more than one carbon. This concept was applied to CDT-BTZ conjugated polymers. Using 5-ethylnonyl side chain R4, it showed an improved supramolecular organization with respect to the conjugated polymer using 2-ethylhexyl side chain R2. 118 The π-stacking decreases from 3.75 Å for two carbon spacers to 3.57 Å for four and five carbon spacers between the branching point and the conjugated polymer backbone.

The same chemical modifications were carried on DPP derivatives to study the impact of shifting the branched point and the effect of the chain length. Three DPP derivatives PDQT: using R1 with two carbon spacer and C10 and C8 chains, R2: two carbon spacers with C10 and C12 chains and R3 with four carbon spacer and C10 and C12 chains. PDQT-1 and PDQT-2 display similar crystallinity while using longer size chains showed much better mobility 3.37 cm 2 v -1 s -1 instead of 2.10 cm 2 V -1 s -1 in PDQT-1. The π-stacking slightly increased from 3.79 Å to 3.86 Å but with no benefit on the mobility. Therefore, the better performance was explained by smoother surface morphology and better interconnected networks and then efficient charge transport. Using longer side chain with shifting the branching point PDQT-R3 showed a further increase in mobility up to 6.9 cm2 V -1 s -1 with lower crystallinity but much shorter πstacking distance (3.68 Å) which is the reason behind the high mobility (Figure 47). 119 Therefore, shifting the branching point in the alkyl side chain reduces the crystallinity but can induce shorter π-stacking distance and planarity. The increase in the carbon spacer length leads to a slight decrease in the solubility of the conjugated polymers synthesized, which decreases the average Mw from 13 kDa to 9 kDa. However, it also results in a red shift absorption and consequently smaller band gap, which means better intermolecular interaction or better ordering in the solid state. The increased intermolecular interactions are explained by a decrease in π-π stacking that could be due to the reduced steric hindrance. These polymers were studied with atomic force microscopy, which suggested the polymers formed lamellar structures with edge-on orientation. 120 Other than the type of alkyl side chain and the branching point position, the position of the attached side chain "substituent position" has a huge impact on the charge carrier mobility.

Thieno [3,4-c]pyrrole-4,6-dione (TPD) based copolymers with thiophene and bithiophene as donor units were investigated. PTPD-1 and PTPD-3 showed better intermolecular interactions. PTPD-3 displayed one of the highest reported mobility. The big difference in carrier mobility was not related to average molar mass, where PTPD-1 owes the largest average molar mass and both polymers are with same type of alkyl chain. Therefore, it is more linked to the position of the alkyl side chain (Figure 49).121 Recently, water-soluble conjugated polymers have attained exceptional interest for high sensitivity bio and chemo sensor applications. To increase the water solubility of conjugated polymers oligoether side chains are beneficial due to their hydrophilicity, their potential to offer solubility in polar solvents with no need of ionic groups as well as their propensity to complex with metal ions if it is required.

Regioregular poly(3-hexylthiophene) is a conjugated polymer with a high mobility and a good chemical stability, therefore, several groups worked to synthesize water-soluble polythiophene derivatives, but most of these polymers were with charged ionic groups. To overcome this ionic character, hydrophilic -(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)methyl side chain has been used . This type of chains allows the formation of a conjugated polymer with well-defined ordered crystalline structure by self-assembly through strong π-π intermolecular interaction of backbones. 122 Other examples of using oligoether side chains are copolymer based on DPP synthesized by Patil and co-workers 123 Indeed, oligoether side chains not only improve the solubility of conjugated polymers in water but also in polar aprotic solvents due to the presence of ether and flexible alkyl chain. 125 Hence, they are interesting to be applied to increase the solubility of conjugated polymers.

To enhance the π-π aggregation and chain orientation:

The properties of conjugated polymers in devices such as solar cells are strongly affected by their morphology and self-organization ability. The type of side chain such as alkyl or alkoxy chains and their position strongly impacts the molecular orientation of the conjugated polymer. 126 However, self-organization is more linked to the use of fluoroalkyl side chains. Semi-fluoroalkyl side chains are famous type of side chains for inducing rigid backbone and molecular organization. The insertion of these side chains in conjugated polymers results in polymers exhibiting high electron mobility values of up to 6.50 cm2 V -1 s -1 for PNDIF-TVT that is naphthalene diimide (NDI) unit alternated with bithiophene T2 donating unit (Figure 51).127 Not only self-organization but also small π-π spacing is preferred in conjugated polymers. Small π-π spacing reduces the energy barrier for interchain charge hopping, which is a crucial charge transport mechanism in conjugated polymers. Organization of π-π stacking is essential to increase the aggregation. The increase in aggregation leads to enhanced solidstate order and better field effect mobility. Polymers aggregation is a strategy used to favor crystallinity and then better performance for applications as organic photovoltaic and OFETs. 128 The structure of the side chains controls the aggregation in the synthesized polymer through the interchain interactions of semiconducting polymers. 129 Another factor that can enhance the aggregation is the planarity of the polymer.

Polaron propagation that has been previously described is related to the chain orientation of the conjugated polymer. For better understanding, two types of packing can occur when a conjugated polymer is applied on a surface: lamellae face-to-face packing model (face on orientation), in this type the aromatic plane of the backbone lies flat on the surface of the substrate and the π-stacking is perpendicular to the substrate. The second type is along π-π stacking direction (edge on orientation), the π-stacking is oriented parallel to the substrate and in the same plane of the charge transport (Figure 52). The face-on arrangement was showed to be promoted by the utilization of branched alkyl side chains due to the bulky and steric hindered chains. Edge-on orientation is obtained by the utilization of linear alkyl chain in some D-A conjugated polymers based on diketppyrrolooyrrole, thienopyrroledione and phenanthrodithiophene. 132 The two kinds of crystalline structure are applicable to different device configurations according to the direction of the charge carrier transport. As an example, in field effect transistors, the molecules are preferred to be with edge-on orientation for better device performance because of the efficient two-dimensional charge transport along the conjugated system and the π-π stacking. 133 . However, polymers with well-ordered face-on orientation are the best for organic solar cells. 134 Then controlling the molecular ordering is essential for achieving high charge carrier transport. A series of DPP quaterthiophene polymer PDQTs have been investigated with three different side chain modifications (Figure 47). The use of branched alkyl side chains with the DPP backbone results in edge -on orientation in the three polymers. 135 The chemical morphology is with tight relation to the molecular orientation of the conjugated polymer. Researchers have found some common properties and functionalization strategies to favor the formation of the desired orientation of molecules of the conjugated polymers according to the fabricated device system.

To increase Stability:

Fluoroalkyl side chains are characterized by their unique characteristics, such as hydrophobicity, thermal stability, chemical and oxidative resistance and self-organization ability, which make them good candidates as side chains for increasing the stability of conjugated polymers.

Synthesis of conjugated polymers such as polythiophene with electron-withdrawing substituents is still limited due to their high oxidation potential of monomers, their substituents reactivity and the steric hindrance among substituents which disrupts the conjugation within the system. A type of side chains that has recently attracted the researcher's attention is the fluoroalkyl side chain due to their amphiphilicity that can have an impact on the thermochromism, liquid crystallinity and solid-state assembly with short alkyl spacer to serve a separation of the conjugated polymer backbone from the electronwithdrawing substituents.

Perfluoroalkyl side chains with direct attachment to the polymer backbone supply the electronic structure of the π-system, but they're still limited to doping procedures for thermoelectric applications. Fluoroalkyl side chains form a helical low energy conformation. 136 With fluoroalkyl side chains, both backbone and side chain are hydrophobic and they are of sufficient difference in size to cause twisting of the conjugated backbone, taking into consideration that the van der Waals radius of fluorine is 1.35 Å that is higher by 12.5% that of hydrogen atoms (1.20 Å). Hence, number of conjugated polymers have been developed with semi fluoroalkyl groups with unique properties such as rigidity, thermal stability, chemical and oxidative resistance, and self-organization of the chains due to their hydrophobicity (Figure 53). Series of poly(3-alkylthiophene), PFT have been prepared by Collard and co-workers with the general structure depicted in figure 47 to investigate the self-assembly and charge transport properties. 137 Introducing fluoroalkyl side chains to the donor-acceptor system permits the synthesis of high electron mobility and air-stable semiconducting conjugate polymers. Naphthalene (NDI) acceptor functionalized with semi fluoroalkyl chain (CH2)10(CF2)7CF3 by Kilwon Cho et al was coupled into two types of donor units: bithiophene (T2) or thienylene-vinylenethienylene(TVT) to form PNDIF-T2 and PNDIF-TVT, respectively (Figure 54).

Figure 54: Conjugated polymers with fluoroalkyl side chains

These two polymers exhibit good solubility in common solvents due to the flexibility of the semi fluoroalkyl side chain with average molar masses of 28 and 33 KDa. The band gaps were found to be 1.61 eV and 1.39 eV for PNDIF-T2 and PNDIF-TVT, respectively. This difference comes from the HOMO level of PNDIF-TVT (-5.38eV) that is higher than that of PNDIF-T2( -5.62 eV) due to the extended π-conjugation. Moreover, the presence of fluorine provokes low LUMO level of both polymers around -4.0 eV. And it was proved that this type of chains enhances the thermal stability, which might be a consequence of the strong organizational properties of semi fluorinated alkyl chains. 127 In particular, the introduction of this side chain results in high electron mobility of 6.50 cm 2 V -1 s -1 for PNDIF-T2.

Side chain engineering is a promising method to apply via chemical modification strategies on the conjugated polymer at the stage of monomer synthesis. It is widely applied in organic synthesis of conjugated polymers for enhanced physical properties through controlling chemical morphology.

III. Synthesis of conjugated polymers:

The three main methodologies that have been developed to synthesize π-conjugated polymers are: oxidative polymerization, organometallic coupling reactions, and synthesis of conjugated polymers with a metal center.

Oxidative polymerization:

Chemical oxidative polymerization COP is a well-known method from aromatic compounds like aniline, pyrrole, phenols, thiophenols, diphenylsulfide and thiophene. The oxidation of the monomer is performed using an inorganic or organic oxidizing agent or by applying a potential (electrochemical oxidative polymerization). In this type of polymerization, cation or cation radical sites are formed in the conjugated molecule (monomer or polymer), in order to do the initiation step. 138 The next step is the formation of dimer, followed by oxidation, coupling and rearomatization and then the chain propagation (Figure 55). However, this type of polymerization lacks selectivity and results in a decrease of the efficiency of the obtained polymer. Therefore, looking for other methods is required such as organometallic coupling reactions.

Organometallic coupling reactions:

Organometallic coupling reactions allow the formation of C-C bonds between aromatic units. It is a powerful tool to synthesize a wide range of macromolecules and conjugated polymers. Different types of coupling reaction have been developed. They are performed in the presence of a catalyst (organometallic compound) in three main steps: oxidative addition, transmetallation and reductive elimination. The oxidative addition is between the organometallic catalyst (zero oxidation state) and a halogen derivative R-X such as iodine and bromine. After the transmetallation, which is the metal exchange step to have an R group instead of the halogen. For the reductive elimination, it allows the formation of the desired C-C bond for the final compound R-R' (Figure 56).

Figure 56: General mechanism of organometallic coupling reactions

According to the type of the catalyst used and the halogen atom, we can classify different types of coupling reactions.

Suzuki Coupling:

It is an organic reaction in the presence of palladium (0) complex as a catalyst and the boronic acid as organohalide partner. This reaction requires the presence of a base, the most common base is alkoxide (OR -) to substitute the halogen with the nucleophile (R-Pd-Nu) at the stage of oxidative addition and to form the borate intermediate (R'-BY2-Nu) to accelerate the reductive elimination (Figure 57).

Stille coupling:

It is a coupling in the presence of palladium (0) catalyst and organohalide, triflate or carbonylchloride. The organic groups are aryl, heterocyclic or vinyl and the metal included in the transmetallation is step is tin (stannic reagent). Knowing that the reaction shows tolerance to many functional groups like amines, aldehydes, esters, ethers and nitrogen groups, and usually the reaction yield is high. 140 However, tin derivatives are toxic. Photoactive benzothiophene BDT D-A based conjugated polymer is an example on Stille coupling polymerization (Figure 58).141

Sonogashira coupling:

Homogenous Pd catalysts such as Pd(PPh3)2Cl2, Pd(PPh3)4 and their derivatives are also used for this kind of coupling reactions in the presence of CuI and inert atmosphere. It was developed by Sonogashira et al in 1975 between vinyl or aryl halides and terminal alkyne. 142 The synthesis of poly(porphyrindithianothiophene) is an example where porphyrine unit is the electron deficient unit and dithianothiophene is the electron rich unit were polymerized in the presence of Pd(0), CuI, triethylamine as a base and toluene as solvent under inert and dry atmosphere (Figure 59). 143

Heck coupling:

It's a palladium catalyzed coupling between aryl or vinyl halides and activated alkenes in the presence of a base. From the mechanistic side, this reaction starts with oxidative addition then, insertion step followed by beta H-elimination instead of transmetallation and reductive elimination to obtain the desired molecule (Figure 60).

Negishi and Kumada couplings:

These reaction couple organic halides or triflates and organozinc compound for C-C bond formation. In general, palladium (0) is used but also a variety of Ni(0) and Ni(II) can be integrated in Negishi cross coupling. What is important in these reactions in the presence of inactivated alkyl electrophiles, transmetallation could occur before the oxidative addition, alkyl zinc would first transmetalate with the nickle catalyst where Nickle takes the halide from the alkyl halide to form alkyl radical and result in the oxidation of the catalyst. The reductive elimination from Ni(II) or Ni(III) if the used catalyst was Ni(I) ( Figure 61). Kumada coupling is similar to that of Negishi by the reaction of Grignard reagent instead of alkyl zinc and an organic halide. It is about four steps, oxidative addition, transmetallation, trans-cis isomerization and then the reductive elimination (Figure 61).

Direct heteroarylation polymerization:

Direct heteroarylation (DHAP) is a recent method for organic conjugated polymer synthesis with less waste and using simpler monomers 145 . It was investigated by Lemaire group for poly(alkylthiophene) synthesis. 146 DHAP is a metal-catalyzed coupling reaction between an arene and an aryl halide (Figure 62). The main advantage of this polymerization is that it can be performed on easily accessible monomers (arenes and arylhalides). It is performed using catalysts based on rhodium or palladium.147 DHAP allows the synthesis of polymers hardly obtained via the traditional coupling (Figure 62).

Figure 62: General reaction scheme of DHAP polymerization compared to classical coupling reactions

In this type of reaction, the precatalyst used and its amount play an important role in the polymerization in obtaining high molecular weight materials and an excess of this reagent leads to high reactivity (Figure 63). 148,149,150 These methodologies using organometallic reactions have advantages inn the synthesis of conjugated oligomers and polymers. They allow building regio-and stereoregular conjugated polymers with a wide variety of functional groups and in general they require mild conditions. The available options appear enough with the increasing demand for structures with optical and electrical properties. 151

Synthesis of polymers with a metal center:

The utilization of semiconductor conjugated polymers has spread in a various area and recently thanks to the transition metals that could form complexes with the monomer units. These polymers which contain metal atoms in their backbone are named as metallopolymer.

The incorporation of a transition metal element is an attractive platform to combine the electronic, optical, magnetic and chemical properties of those complexes with the organic conjugated polymers. This transition metal insertion to the π-conjugated system allow the tunability of the physical properties of the resulted materials through a strong interaction between the metal and the organic component to provoke a distinctive photophysical, electrochemical and photochemical properties.

The introduction of a metallocene unit into the conjugated chain may affect a range of properties as redox, magnetic, optical, and electronic properties, where alkynyl ligand can bridge multiple metal center. These polymers prepared by the interaction of alkaline metal or alkaline earth metal alkynyl complex with transition metal halide MX (M=Pt, Pd or Ni as transition metal and X= Cl, Br, I) using copper-catalyzed dehydrohalogenation, oxidative coupling and Alkynyl ligand exchange. 152

Copper catalyzed dehydrohalogenation:

In this type of polymerization, the cupreous halide plays the role of a catalyst between diterminal alkynes and transition metal halides (Figure 64). 153

Figure 64: Copper catalyzed dehydrohalogenation

For preparation of oligomers and polymers using this method, the number of equivalents must be not in much excess to avoid the formation of small compounds. Therefore, there is stoichiometric restriction on reactant. However, this type of polymerization proceeds smoothly at room temperature and under reflux.

3.3.

Oxidative coupling:

In this reaction, a catalytic amount of a cuprous halide and oxygen is used to have coupling with two terminal alkynyl groups (Figure 65). 154

Figure 65: Homocoupling of terminal alkynes

Oxidative coupling is a convenient preparative method, where no stoichiometric restriction. Consequently, the degree of polymerization is usually high.

3.4.

Alkynyl-ligand exchange:

This type of reaction was carried for metallopolymer with Ni. It is also a copper catalyzed reaction that involves alkynyl ligand in the presence of amine solvents with an addition of PR3 to suppress the phosphine dissociation from the metallic center (Figure 66). 155 Alkynyl polymers are well-studied type of organometallic polymers since these polymers have unique properties such as liquid crystalline properties and electrooptic behavior. Involving Pt as transition metal in these polymers has attracted attention over the past decades. A lot of studies were carried to provide better understanding of the metal center influence and spacer group on the electronic excitations and the concept of triplet state in these complexes. This will be more explained in chapter two of this manuscript.

IV. Applications of conjugated polymers in materials for energy:

Conjugated polymers have received attention in various electronic devices due to their solution processability, light weight, flexibility and low thermal conductivity. Both n-type and p-type conjugated polymers have been investigated for high performance devices. 156 Conjugated polymers and recently metallooligomers are widely studied and explored in the field of organic photovoltaics as organic semiconductors in the active layer of organic solar cell. Conjugated polymers can be used as hole transfer materials, electron transfer materials and an interface layer for better charge transfer. 157 Metallooligomers and metallopolymers will be studied in chapter two for solar cells application.

Currently, conjugated polymers are also hailed as promising organic thermoelectric since their constituents are more abundant than inorganic counterparts, they can be scaled up for mass production and because of their flexibility, they can harvest wasted heat from a variety of shapes. 158 The use of conjugated polymers in thermoelectrics will be more explained in chapter three of this manuscript. N-type conjugated polymers are still suffering from poor stability and low electrical conductivity. Therefore, in this thesis we are more interested in synthesis new n-type conjugated polymers. However, the synthesized polymers will be also used before doping process in n-type organic field effect transistors (OFETs) as organic semiconductors.

I.

Introduction to organic solar cells:

1. Solar cells:

The history of solar cells started in 1876 when Grylls with Richard Day, who is one of his students discovered that electricity can be produced when selenium was exposed to light. 159 In 1953, Calvin Fuller, Gerald Pearson and Daryl Chapin discovered the silicon based solar cells, which can give an efficient amount of energy for some small electrical devices to work. 160 In 1956, commercially the first solar cell was available then a lower cost solar cell was discovered at the beginning of 1970. 161 The efficiency of solar cell is evaluated by the power conversion efficiency PCE. This value is determined by the figure of merit:

Voc is the open-circuit voltage, when there is no current running through the device, Isc is short-circuit current density at V= 0, which is the maximum photocurrent generation value.

FF is the fill factor and Pin the incident light power (Figure 69).

Where FF is the ratio of the maximum power divided by Voc*Isc. For FF over 60 %, it is considered benchmark for solar cells. Recycling technologies to reuse silicon from the solar cells are still not commercially available. To overcome the recycling problems of silicon scientists developed the organic or hybrid solar cells combined with dyes to replace the inorganic materials in the traditional solar cells. Recently, perovskite solar cells are of researchers interest. Technical advances provoke a jump in conversion efficiency to reach 25 %. 166 Nevertheless, the utilization of organic materials is gaining much interest in the preparation of solar cells. Indeed, organic materials can hold up the potential to develop environmentally safe materials for long-term technologies such as organic solar cells.

Organic solar cells:

Organic solar cells have important properties starting from the low cost of materials, less toxic components, and high throughput roll-to-roll production to the mechanical flexibility and light weight. 167 In this area polymer solar cells have attracted a great attention in the research field because of the worthy advantages related to polymer solar cells over the previous generation of inorganic solar cells. The power conversion efficiency (PCE) has increased from 1 % to over 8 % during 1990's. 169 The PCE value is calculated by the same method used for inorganic solar cells, which is the use of figure of merit.

The parameters used for calculating the power conversion efficiency depend on the energy levels of donor and acceptor used in preparing the organic solar cell, for example Voc depends on the energy levels of HOMO D of the donor and LUMO A of the acceptor in particular to the offset of a proportional relation EHOMO D -E LUMO A .

And FF has positive depending on ∆HOMO energy levels of the donor and acceptor in the blend. Changing the HOMO-HOMO offsets provokes change in the FF value.

The most well studied system in the field of organic photovoltaics OPV consists of a blend of P3HT and (6,6)-phenyl-C61-butyric acid methyl ester PC61BM 170 with maximum power conversion efficiency reaching 4.24 %. 171 In the last fifteen years, a significant progress has been made to enhance the power conversion efficiency (PCE) of polymer bulk solar cells and the achieved efficiencies have increased from less than 1 % in the poly (phenylenevinylene) 167 (PPV) system in 1995 to 4-5 % in solar cells based on poly (3-hexylthiphene) (P3HT) system in 2005, to achieve a yield of more than 11 % in 2016.

After around thirty years of progress, the PCE of organic solar cells has been increased to reach 20 % to approach the traditional counterparts. However, the efficiency of the polymer solar cell is still lower than that of the silicon solar cells that is of PCE 29.1 %172 and that of Perovskite solar cells which is approaching 26 %. 173 Stability is considered as limitation for organic solar cells, since under illumination and simultaneous exposure to water vapor or oxygen, degradation of the active layer occurs. 174 The progress of different solar cells is illustrated in the chart of figure 72.

Figure 72: Chart illustrating the performance of solar cells from 1975 to 2020 175

The performance of BHJOSCs could be enhanced by three main strategies. First, to vary the architecture of the organic solar cells. Second, to develop new p-type and n-type semiconductors. Third, to control the morphology of acceptor/donor blend in the active layer of BHJOSCs.

Architecture of organic Solar Cells:

Organic Solar cells are classified into three configurations: regular, inverted and tandem depending on the arrangement of the layers in the solar cell (Figure 73), where organic solar cells are made-up of five main layers. Most of organic solar cells are with an organic layer inserted in between two different electrodes. One of the electrodes should be (semi-) transparent anode electrode as transparent oxide (TCO) as indium-tin oxide (ITO), also thin metal layer can be used. The second electrode is the cathode. It is usually aluminum (calcium, magnesium, gold and others are also used) 176 and two layers inserted between the electrodes and the active layer as electron transporting layers (ETL), which extract the electrons from the active layer to the electrode and hole transporting layer (HTL), which extracts and transports the holes in the active layer to the electrode and acts as energy barrier to prevent the electron transfer to the anode electrode. In tandem solar cell we can define the interconnecting layer (ICL) that is electrically connects two sub cells and has a role in determining the performance of the organic solar cell.

The inverted device architecture gained research attention due to the device stability. The polarity of charge collection is opposite to the regular configuration. 177 In my project, the donor polymer will be evaluated with the regular architecture.

Active Layer :

Moreover, these cells also classified according to the type of their active layer architecture: single and double.

Single active layer structure:

Single active layer structure organic solar cells consist of an active layer made up of one type of semiconductors (Figure 74). The major limitation of this type of organic layer is that the electric field generated from the difference between two conductive electrodes is not always efficient to split the excitons. Therefore, Bulk heterojunction is the most utilized p-n junction organic solar cells. 179 It shows a relevant morphology to favor efficient charge separation and transport. Also, it provides continuous network for charge transport. Nevertheless, because of the different chemical nature of the donor and acceptor, it is usually complicated to control the active layer morphology for better device performance. 180 The performance could be enhanced by controlling the morphology of active layer via increasing the D/A interface and to lead to The conversion, of incident photons into electric current in bulk heterojunction involves four fundamental steps (Figure 77):

1.

Absorption of light and the generation of exciton 2.

Exciton diffusion to the D-A interface (length around 10-15 nm) 3.

Exciton dissociation at D-A interface to free charge (hole as positive charge and electron as negative charge) 4.

Then, transport of the charges to the respective electrodes

Figure 77: The mechanism of incident photon into current generation BHJ OSCs

After the photon absorption there are two possible pathways for the excitation as shown in figure 78. In channel one, the excitation occurs in the donor part and then the electron is transferred from the donor to the acceptor. In the second pathway, the excitation occurs in the acceptor part and then followed by electron transfer from the acceptor to the donor. The nature of the acceptor is the main parameter in the determination of the mechanism. Generally, channel one dominates the photocurrent generation when fullerene-based acceptors are used, while the two excitation pathways occur in non-fullerene organic solar cells. 181 In this thesis, we are interested in the mechanism of channel I.

Figure 78: The photon absorption possible pathways represented in two channels (I, II)

The performance of the solar cells depends on the nature of the donor and acceptor used in the blend of the active layer. Enhancing optical properties, suitable electronic band's structure, charge transport with an appropriate molecular organization are promising strategies to increase solar cell performance. This could be achieved by modifying the molecular design of the donor and working on its functionalization. Therefore, tuning the optical, electronic and optoelectronic properties relies on the structure of the polymer used. The donor-acceptor materials in BHJ OSCs must have key properties: 182 1.

Complementary absorption spectrum between donor and acceptor to broaden the absorption wavelength to absorb the maximum of solar light (to approach sunlight spectrum with air mass coefficient AM 1.5). Therefore, allowing less energetic photons to produce excitons.

2. Suitable electronic structure with appropriate band levels for effective electronic transfer.

3.

High charge carrier mobility and well-balanced electron and hole mobilities to prevent recombination.

4.

Nanoscale phase separation of donor/acceptor blend in the active layer.

5.

Donor/acceptor vertical segregation.

6. How to enhance the PCE:

6.1. Tuning the electronic structure of D/A:

In order to enhance the PCE, the material must show high absorption capacity with the determination of the molar extinction coefficient (ε𝝀) and broad absorption wavelength range close to that of sunlight spectrum with air mass coefficient 1.5 AM. One of the efficient ways to broaden the absorption range of the polymer is by narrowing down the optical band gap. 183 There are several strategies to decrease the band gap as explained in chapter one of the manuscript:

1.

Increase the effective conjugation length.

2.

Increase the planarity.

3.

Allow an increase in the alternating donor-acceptor π-conjugation.

4.

Increase the stability of quinoid form. Therefore, looking for a coplanar main chain of the conjugated polymers allows the extension of the conjugated polymer, increases in the intermolecular π-π stacking; hence, it improves the charge transport properties.

In organic solar cells, there are two important parameters ∆E1 and ∆E2 (Figure 79). ∆E1 is the energy difference between the LUMO level of the donor and the LUMO level of the acceptor. It should be around 0.3 eV or less depending on the type of the acceptor used to allow the dissociation of the exciton. ∆E2 is the energy difference between the LUMO level of the acceptor and the HOMO level of the donor polymer. ∆E2 is proportional to Voc, where Voc is the value of the maximum voltage that the solar cell can extract for an external circuit, and it is originated from the energy offset between the HOMO of the donor and the LUMO of the acceptor such as PCBM. Voc is expressed in the following equation:184 HOMO and LUMO levels have a remarkable influence for obtaining high PCE, since they are strongly related to the Voc and the charge separation efficiency of OSCs. For designing efficient p-type materials, it is important to downshift the HOMO level and keep the LUMO level above that of the n-type material. 185 Good solubility in common organic solvents, good film, rigidity, self-assembly, high molecular weight, and ambient stability are required parameters to be taken into consideration during the synthesis of p-type materials.

𝑉 𝑜𝑐 = (1/𝑒)|𝐸 𝐻𝑂𝑀𝑂 𝑜𝑓 𝑑𝑜𝑛𝑜𝑟 | -|𝐸 𝐿𝑈𝑀𝑂 𝑜𝑓 𝑎𝑐𝑐𝑒𝑝𝑡𝑜𝑟 | -0.3
According to Scharber and co-workers, the ideal polymer for fullerene acceptor as PCBM, must have a LUMO level between -3.7 and -4.0 eV and small band gap of 1.5 to 1.8 eV. 186 High average molar mass is not less important parameter. Studies on the influence of the average molar mass on electronic properties of the polymer showed that the performance of BHJ solar cell is improved as the average molar mass of the conjugated polymer is increased. As an example on this property, BHJ solar cell based on poly[ (4,4-

didodecyldithieno[3,2- b:2′,3′-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl]
active layer has increased short -circuit current density from 4.2 to 17.3 mA cm -2 and increased fill factor FF from 0.35 to 0.61 with the increase in the average molar mass from 7 to 34 Kg.mol -1 , which results in increased PCE value from 1.2 % to 5.9 %. 187

Molecular organization:

The major issue surrounding polymer solar cells and more precisely the polymer solar cells is the low power conversion efficiency. Recent advances in their performance are through narrowing the band gap to enhance the short circuit current, while keeping low the HOMO level to increase the open circuit voltage Voc. Another problem that organic solar cells are facing is the low stability under ambient conditions or the low stability of organic materials within the device and during the cell manufacturing.

Therefore, the main goal in this field is to obtain high charger carrier mobility in the donor materials in the active layer blend. Such property is achieved for materials with threedimensional order with semi-crystalline film morphology. Structural and molecular parameters are crucial ingredients for high PCE in polymer solar cells. 188 Favoring the face-on orientation is also necessary for building an organic solar cell (Figure 80). Besides, side chain engineering is a method, which is used to enhance these properties and to improve the solubility. 189 Another interesting property is creating a rigid conjugated backbone to enhance the crystallinity and to promote charge transport. 190 Since, increasing the planarity is required to increase the intramolecular interactions.

Designing the appropriate donor and acceptor materials for organic solar cells must be taken into consideration as a key step in obtaining an enhanced performance.

The choice of the donor and acceptor materials for the blend preparation

in bulk heterojunction is very important to the overall performance of the organic solar cells:

Acceptor material:

The history of acceptor materials has been started when Sariciftci and al have discovered that the photo-induced electrons can transfer from the polymer to a fullerene molecule. 191 PC61BM is one of the common fullerene acceptors used in OSCs, it is composed of a C60 fullerene cage, aryl group, alkyl chain and end group, thus serving four possible variables to enhance the efficiency of fullerene based solar cells by modifying these four terms. It was widely used because of its better performance compared to that of pristine C60 (Figure 81). Although fullerene acceptors are widely used in the field of BHJ, they have their intrinsic limitations: restricted tunability of electronic structure and then no variation of the energy levels, weak absorption potential in the visible and near infrared ranges, morphological instability and expensive synthetic procedures. 193 PCBM based blend in PffBT4T-based polymer yield PCE around 12 % that is among the highest values in fullerene based OSCs. 194 By 2015, Lin and co-workers reported the non-Fullerene acceptors NFAs, which showed better absorption than the fullerene in the visible region. Hence, NFA-based OSCs have attracted much attention and recently their performances have made a significant progress with an increase in the PCE from 12 % to around 20 % in bulk heterojunction solar cells. 195 NFAs possess definite advantages in the absorption spectrum complementary with donor material in binary and ternary systems. NFAs are more flexible to vary the HOMO and LUMO energy levels in electronic structure. They have tunability of the band gap with higher LUMO level and then higher Voc and Isc. 196 Hence, NFAs have less energy loss and better exciton dissociation with the possibility to alter the optoelectronic properties. Moreover, they have better molecular organization with increased donor /acceptor interface and face-on orientation. NFAs can be classified into small molecules and polymeric NFAs.

Small molecules include imide-based NFAs and A-D-A type NFAs. A-D-A are conjugated Push-Pull structures, where A represents electron withdrawing moieties and D represents electron-rich moieties, such combination aims a decrease in the band gap. ITIC (Figure 82) has been reported in 2015 in Zhan's group, which is based on indacenodithienol [3,2b]thiophene (IDTT) as the core and 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile (INCN) group with 4-hexyl groups substituted on it. These carbonyl and cyano groups down-shift the LUMO energy level and the push-pull structure induces an intramolecular charge transfer with extension of the absorption range, while the hexylphenyl group restricts the aggregation. This type of acceptors shows an intense absorption in 500-800 nm range and low LUMO level with promising PCE. 195

Figure 82: Common Small molecules NFAs

The efficiency of BHJ approaches 19 % using a small molecule NFAs ITIC-4F known as IT4F in PM6/IT4F blend (Figures 82 and88). 197 In 2019, new NFA with A-DA'D-A structure, Y6, which is another type of small molecules NFAs has showed one of the highest PCE (15.7 %) with high Voc of 0.825 V, fill factor of 74 % and Jsc of 25.2 mA cm -2 due to the preservation of the conjugation along the length of the molecule due to the fused dithienothiophen[3,2-b]-pyrrolobenzothiadiazole (TPBT) unit, which allows the tuning of the electron affinity with -5.65 eV HOMO level and -4.10 eV LUMO level and 1.33 eV band gap. 198 Therefore, series of Y6 derivatives have been developed such as Y6-Se which has enhanced quinoidal character leading to lower band gap because of better orbital overlap in π-conjugated system with more polarizable delocalization of the electron cloud in Se compared to S atom in thiophene but their absorption range is not broad enough compered to Y6 (Figure 83). With appropriate donor materials, the PCE reached 18.1 % in PM7:PM7: Y6: PC71BM quaternary OSCs. 199

Figure 83: Small molecules NFAs with A-DA'D-A structure

Recently, polymeric NFAs acceptors are developed. The most known building blocks in this type are perylene diimide (PDI), naphthalene diimide (NDI), bithiophene imide (BTI) and B-N bridged bipyridine (BN-Py) and some D-A copolymers including the small NFAs as acceptor units such as PDI-vinylene (PDI-V), NDI-bithiophene NDI-2T and cyclopenta-dithiophene (CPDT-TPD)(Figure 84). 200 As all polymer solar cells, they have advantages as the structural flexibility, morphological stability and superlative mechanical properties.

Figure 84: Examples of NFAs based on known building blocks (PDI, BTI, BN-Py).

In 2022, PY-2S has been synthesized with fluorine functionalized derivative PY-2S-F and two PY-2Se derivatives Y-2Se-F, and PY-2Se-Cl (Figure 85). The maximum PCE of 16.1 % achieved is with the use of PY-2Se-Cl as acceptor blended with PM6 as donor material. Fullerene derivatives have been widely used as electron acceptors in organic solar cells. Yet, NFAs materials have emerged as promising candidates to replace the fullerene molecules.

However, the active layer, including donor/ acceptor materials, has been a key factor for achieving high PCE values. Therefore, the progress in the efficiency of organic solar cells relies on developing both acceptor and donor materials. In the next paragraph, donor materials from the literature are discussed.

Donor materials:

The small band gap is not a guarantee for high PCE value. Proper HOMO and LUMO levels are crucial for the efficient charge transfer to the acceptor material and to obtain large Voc of the device. More properties are essential such as high charge carrier mobility and favorable morphology when blended with the acceptor. 202 Donor materials are classified into three main types: small molecules, conjugated polymers and metallooligomers.

Small molecule donor materials:

The first generation of donor materials is composed of small molecules such as DPPbased small molecule materials, which offers advantages such as ease of fabrication and purification, determined and uniform structure, and high open circuit voltage Voc compared to the polymers. 203 .

A family of donor materials has been developed based on Diketopyrrolopyrrole (or pyrrolo [3,4- 86) that is a new pigment class, which is obtained in 1974, but it was not reported until 1993. In 2008, DPP-based small molecules and polymers were applied as organic semiconductors in organic photovoltaics and organic thin film transistors. Through the engineering of the energy levels of DPP derivatives, they could be used as p-type, n-type and ambipolar semiconductors. 204

c]-pyrrole-1,4-dione) (Figure

Figure 86: Chemical structures of DPP chromophores

This type of molecules has lower charge mobility compared to larger systems, and shorter effective carrier lifetime in a comparison between the efficiency between monoDPP molecule and bis-DPP molecule as p-type materials in organic solar cells. Developing a large conjugated system would be more promising in this application.

Polymer donor materials:

In 2016, the efficiency of polymer organic solar cells reached 11 % using a blend based on poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)alt-(3,3′′′-di(2-nonyltridecyl)-2,2′;5′,2′′;5′′,2′′′-quaterthiophen-5,5′′′-diyl)] (PffBT4T-C9C13) as donor and PC71BM as acceptor. 205 Later, Benzodithiophene (BDT) is considered as one of the most important units as an electron donating block in the synthesis of D-A donor materials. PBDB-T-2Cl is a chlorinated copolymer, which consists of BDT as donor unit and 1,3-bis(4-(2-ethylhexyl)thiophen-2-yl)-5,7-bis (2-alkyl)benzo[1,2-c:4,5-c′]dithiophene-4,8-dione (BDD) as acceptor unit. Photovoltaic characterization of PBDBT-T-2Cl: IT-4F shows high PCE of 14.4 %206 (Figure 87).

Figure 87: The structure of PBDB-T-2Cl polymeric NFAs

PM6 is another copolymer based on fluorothienyl-substituted benzodithiophene with deep HOMO level (-5.50 eV), which leads to lower Voc and reduced Vloss. It exhibits strong π-π interaction and dominant face-on orientation. The performance of organic solar cells based on PM6:IT-4F is of high PCE around 13.5 % due to the fluorination effect. 207 The PCE using PM6:IT-4F blend approaches 19 %,208 that makes fluorinated donor and acceptor blend PM6:IT-4F a promising candidate for large scale production (Figure 88). DPP is an interesting unit due to the planar conjugated bicyclic structure that leads to strong π-π interactions, and the presence of a lactam part that provokes a strong electron withdrawing effect, which makes them good accepting units in optoelectronic materials (Figure 86). The solubility of these DPP based materials could be modified with solubilizing alkyl chains at the N moiety of the lactam using linear or branched alkyl chains. 209 DPP has been used as a building block in small molecules and in conjugated polymers.

DPP-based conjugated polymers with common feature used for photovoltaic is the small band gap in range 1.25-1.55 eV,210 that creates a broad optical absorption up to 1000 nm, good film-forming characteristics and film morphology resulting in good FF and high short circuit current Isc. Hence, a high and remarkable PCE exceeded 10 % in single junction and 11 % in multijunction organic solar cells were obtained. 211 Several publications have been done in improving the PCE of photovoltaic by working on the developing various DPP-based conjugated polymers derivatives as donor materials through chemical modifications for higher charge mobility with keeping in mind the donoracceptor approach.

PBDTT-FDPP, PBDTT-DPP and PBDTT-SeDPP (Figure 89) are three copolymers based on BDT as donor unit and DPP as the acceptor unit with promising efficiencies. The PCE is around 7 % in PBDTT-SeDPP: PC71MB and around 4.5 % in PBDTT-FDPP: PC71MB and 6.4 % in PBDTT-DPP: PC71MB. 212 The optical band gaps are 1.51, 1.46, and 1.38 eV, respectively. DPP2TBP (Figure 89) is another DPP based conjugated polymer flanked with two thiophene units and two phenyl rings with good PCE of 5.7 % in DPP2TBP: PC71MB with optical band gap of 1.63 eV. 210 One of the electron donors with DPP unit is PDPP3T, which is a copolymer of DPP and terthiophene (Figure 89). PDPP3T affords high PCE of 7.4 % in organic solar cells with PC71MB as acceptor material. PDPP3TaltTPT is a derivative of PDPP3T with enhanced PCE of 8 % in a blend with PC71MB material (Figure 89). 213

Figure 89: DPP based polymeric NFAs

Several analogues of DPP based conjugated polymers have been synthesized with phenyl DPP-P, thiophene unit DPP-T and with selenophene DPP-Se. The combination of these heterocyclic molecules with covalent bond to the lactam ring at position 3 and 6 opens the door in a multitude of D-A combinations for optimized electronic properties (Figure 90). Thiophene unit has shown enhanced co-planarity and hence efficient π-π stacking, where the donating strength and then the quinoidal form are affected due to the decrease in aromatic resonance energy compared to phenyl units. 214 Therefore, the DPP that is already widely used in the literature as a building block in donor materials attracts the attention for further chemical modifications while looking for enhanced PCE.

Figure 90: The differences in chemical properties of DPP unit engaged to different donor units

In extensive search for new semiconductors for optoelectronic applications, metallopolymers attracted attention due to their properties such as reversibility, solubility besides of their optoelectronic properties to be used as donor materials.

Metallopolymers:

Metallooligomers can be considered as the third type of donor materials. The main reason to use this type of polymers is the presence of a transition metal in the backbone of the conjugated polymer, which can change its coordination number or oxidation state. Hence, this process can modulate the conductive material between high and low conductivity. 215 Metallopolymers offer the opportunity to tune the electronic structure of the polymer due to their small ionization potential. Upon direct contact with any illumination source, the excitons are generated followed with photon interaction leading to a reduced band gap. In main chain polymers this process is linked to the ligand used which represents the conjugated unit. These polymers are of tunable band gap nature, controlled morphology, long term stability, enhanced light absorption properties and high carrier mobility. 216

Metal ligand coordination mode :

We can classify metallopolymers into two main types: Metallopolymer based on Nheterocyclic ligand and metallopolymer with metal-carbon alkyne conjugated system.

Metallopolymer based on N-heterocyclic ligand:

Several N-heterocyclic ligands have been used with transition metals due to their high binding affinity to metal ions to develop metallopolymers, as an example: Bis-terpyridine-Zn metallo-homo polymers derivatives (Figure 91). The second type of the conjugated system coupled with a transition metal for metallopolymers synthesis is the alkyne group system. There is a wide area of publications on this type of metal-carbon alkyne conjugated system. Therefore, poly(metal acetylide)s or so called Polymetallaynes,bis(acetylides) (Figure 92) are a well-studied class of main chain metallopolymers using ionic metal-carbon bond. 218

Figure 92: Poly(metal acetylide)s structure

The start of this metallopolymers was in 1970s with polymeric Pt and Pd by Sonagashira group. 219 These polymers involve group 8 to group 10 transition metals with increased stability with heavier metals that could be due to the increased ionic character of metal-carbon bond and the geometry type of the metal.

In this thesis we are interested in polymetallayne with Pt transition metal of group 10 and a spacer unit (Figure 93). Given all the consideration above and the intrinsic properties of the transition metal insertion in conjugated polymers backbone on the photophysical properties, DPP-based D-A metallooligomers attract a huge attention as donor materials for organic solar cells and more precisely in BHJ OSCs.

Metallooligomers in organic solar cells:

In 2019, Zhan, Wong and al220 have reported a new series of conjugated organometallic D-A polymers with DPP core flanked with thiophenes ended with a triple bond connected to Pt-complex. These compounds are used as donors in BHJ solar cells, and the devices exhibit PCE from 0.33-1.40 %. However, the Pt containing metallooligomers attract widespread attention because of their additional advantages to enhance optical and optoelectronic properties. The solubility of the metallooligomer is increased with alkyl chain on lactam function and bulky phosphines, like P1, P2 and P3 represented in figure 94. Besides, the insertion of a supplementary thiophene for P3 helps to increase the conjugation length, which can tune the levels of the bands from their electronic structure with a decrease of the optical band gap. But the rigidity of the organic part could increase, hence the decrease of the solubility could be overcome with the presence of a solubilizing chain n-C6H13 on the additional thiophene moiety (Figure 94). In the literature, the increase of the average molar mass (Mn) and the π-aggregation of the chain lead to the enhancement of optoelectronic properties. 221 A better solubility is favored using branched chains and bulky phosphines, it helps to prepare metallooligomers with higher Mn. However, the use of linear chain is still interesting to improve aggregation, but the risk is a decrease of the solubility. Hence, a balance must be made between good solubility with PBu3 and improved aggregation with linear chain n-C8H17 as compound P3 (Figure 94). It has a lower Mn but close to those of P1 and it exhibits a better PCE of 1.40 % (P1, PCE= 0.28 %) with PC71BM as acceptor.

In addition, the advantages of the strategy applied for the preparation of P3 is the increase in the conjugation length with the insertion of two thiophene units, the decrease of the optical band gap and the enhancements of the optical properties by increasing the wavelength range. Comparison of the absorption spectra of P2 and P3 shows a bathochromic shift of 28-30 nm of the absorption wave onset (𝝀 abs (onset) ). A narrower optical band gap of 1.69 eV is obtained for P3 with respect to 1.81 eV obtained for P2. 222 Based on literature results, the team has decided to synthesis an analogue P1' of P1 (Figure 95) as a reference compound. Our collaborator from LNMIIT in India, Pr. Ganesh D Sharma used P1' as donor with PC71BM in BHJ solar cells and the performances were evaluated with a PCE of 7.62 %. The significant difference with P1 from the work of Wong and al 220 is the application solvent vapor annealing treatment (SVA) on the active layer to improve the molecular organization of the blend for an enhancement of the performances. 223 This work was made during the PhD of Mélodie NOS (2015-2018) in the group Polymers & Materials, POHET team. A part of it was dedicated to the preparation of narrow band gap metallooligomers to increase the wavelength range for enhanced optical properties to improve the solar cell performances. This work is summed up in the following part "preliminary results".

Preliminary results:

In the team POHET, the first metallooligomers have been prepared during the PhD of Mélodie Nos (2015-2018). As described in scheme 1, the metallooligomers are synthesized by a dehydrohalogenation reaction between a deprotected ligand and a trans-PtCl2(PBu3)2 complex in the presence of CuI and a base.

Scheme 1: The general synthesis of metallooligomers using dehydrohalogenation reaction

The metallooligomer P1' has been synthesized as a reference compound. In order to decrease the optical band gap, two strategies were applied based on the increase of the conjugation length as described in figure 95. The first strategy is to add two thiophene (T) units with the preparation of PA and the second strategy is to use T-DPP-T dimers in the organic part of the ligand with the preparation of P2' (Figure 95). The metallooligomers were purified on biodead X1® then characterized by 1 H, 31 P{ 1 H] NMR and by GPC for average molar mass determination. P1' has the higher average molar mass of 18.2 Kg.mol -1 with Ɖ of 2.1 compared to PA (Mn = 12-13 Kg.mol -1 , Ɖ =2.3) and P2' (Mn = 6-7 Kg.mol -1 , Ɖ =11.1). P2' has the lowest Mn and the highest dispersity. This could be explained by an instability of the deprotected ligand during the preparation of the metallooligomer (Table 1). The optical properties were investigated by absorption spectroscopy. The spectrum of PA shows an increase in the 𝝀abs (onset) of 66 nm in comparison to P1', which evidenced the decrease of the optical band gap of 1.72 eV in P1' to 1.60 eV in PA. However, strategy 2 was more efficient in the decrease of Eg opt because the absorption spectrum of P2' exhibits a bathochromic shift of 𝝀abs (onset) of 156 nm, which corresponds to a narrower optical band gap of 1.42 eV for P2' in respect of 1.72 eV for P1' (Table2). The values of HOMO and LUMO levels were determined from onset potentials obtained with cyclic voltammetry, as well as the corresponding band gap values of the three metallooligomers P1', PA and P2'. P2' shows a band gap of 1.41 eV, which is smaller with respect to 1.71 eV and 1.62 eV band gaps of PA and P1', respectively. The smaller band gap of P2' could be due to the extension in the conjugation length of the conjugated backbone. The bands electronic structure and the band gap values make P1', PA and P2' promising candidates as donor materials associated to acceptors in solar cells.

Therefore, the photophysical properties of P1' and P2' were investigated to evaluate the time of electron transfer and recombination with fullerene acceptor PCBM. Both metallooligomers exhibit fluorescence lifetimes in ps timescale, which is long enough for efficient photo-induced electron transfer to the acceptor (PCBM). 222 These results are promising; hence, they were used in BHJ solar cells as donors. Nevertheless, because of limited quantities of PA, this metallooligomer was not used as a donor in BHJ solar cells.

The photovoltaic performances of BHJ solar cells were investigated with P1' and P2' as donors with PC71BM as acceptor with optimal weight ratio donor: acceptor of 1:1.5. The average values of PCE are 7.62 and 9.54 % for P1': PC71BM and P2': PC71BM, respectively (Table 3). In the literature, Miyake and al have synthesized an analog of PA. 224 The difference is the functionalization of the lactam functions with branched alkyl chain instead of the linear chain of PA. This compound exhibits a lower average molar mass of 8.8 Kg.mol -1 . 224 The electrochemical, optical and optoelectronic properties were not investigated because of its poor solubility contrary to PA which exhibits a good solubility (Figure 96).

Figure 96: The metallooligomer synthesized in the team

Based on these preliminary results, it would be interesting to prepare larger quantities of PA and to use it as a potential donor in BHJ solar cells. Another aspect is to overcome the stability problems of the deprotected ligand L2' which prevents the formation of longer chains P2'. Therefore, the objectives are the preparation of longer chains metallooligomers of PA for studying its photovoltaic performance in BHJ solar cells and to synthesize new ligands with higher stability than L2' for a narrow optical band gap metallooligomers (Eg opt. =1.4-1.5 eV).

II.

New DPP based metallooligomers:

The objective of my project is to improve the strategies 1 and 2. For strategy 1, my work focused on the increase of the average molar mass by (1) the improvement of the reaction conditions of metallooligomers PA preparation and by (2) applying functionalization step of two thiophene moieties with solubilizing chains C12H25. For strategy 2, the aim is to overcome the stability problem of the deprotected ligand L2'. Hence, we have decided to synthesize a new ligand LC for the preparation of a new narrow band gap metallooligomer PC with the insertion of EDOT unit with a better stability and prepared from an easier synthesis. The targets are depicted in figure 97. The metallooligomers are purified by biobead X1®. This exclusion steric static phase permits to remove the remaining ligand and impurities. The formation of the metallooligomers is checked by 31 P{ 1 H} NMR with the observation of a single signal attributed to phosphorous atoms of the phosphines and a value of the coupling constant JPt-P close to 2200-2600 Hz, which corresponds to trans geometry of the ligands in the square planar [Pt]complex. The complexation of the ligand to platinum is evidenced by 1 H NMR with a variation of the chemical shift of the protons from thiophene units. Then, the average molar masses of the obtained metallooligomers are determined by GPC. These data could be confirmed by MALDI-TOF analysis carried out by Julie Hardouin at PBS laboratory and PISSARO platform, Rouen. The optical properties are investigated by absorption spectroscopy on liquid and thin films with the determination of 𝝀abs (onset) to calculate the optical band gap. In parallel, the electrochemical properties are studied by cyclic voltammetry, carried out by Muriel Durandetti in COBRA laboratory, Rouen to determine the HOMO and LUMO levels and the value of the electrical band gap (Eg elec. ). In addition, the thermal properties were investigated. Thermogravimetric analysis (TGA) was carried to indicate the decomposition temperature of each metallooligomer as well as XRD was used to study the microstructure.

1.

Strategy 1: to increase the molecular mass Mn of DPP based metallooligomers:

The objective of this strategy is to increase the average molar mass by following two ways: (1) Improving the reaction conditions of metallooligomer PA preparations and (2) functionalizing of thiophene units with a solubilizing chain for the synthesis of a new metallooligomer PB.

Improving the reaction conditions of metallooligomer PA:

To begin with, the reaction conditions of the dehydrohalogenation, depicted in scheme 2, have been modified to increase the average molar mass of PA. In prior, larger quantities of ligand LA are required to test several conditions. obtained with a yield of 70 %. Then, 2 was brominated at the position 2 of the thiophene moieties with N-bromosccinimide (NBS) to form compound 3. It is carried out away from light to avoid side reactions. The brominated compound 3 was isolated with a yield of 90 %. Afterwards, thiophenes are inserted after a Stille coupling reaction between compound 3 and 3-tributylstannyl-thiophene catalyzed with Pd(PPh3)2Cl2. The compound 4 was obtained with a yield of 60 %.

The bromination of compound 4 is the limiting step because of the formation of two products monobrominated 5 and bisbrominated 5', and with the consumption of the starting materials in a side reaction of oxidative polymerization. The purification step for separating the two compounds 5 and 5' is tedious. Their presence was confirmed by 1 H NMR and mass spectrometry analysis. Therefore, the mixture was directly engaged in Sonogashira coupling reaction for the preparation of ligand LA.

To improve the yield of the formation of ligand LA, the reaction conditions of the bromination step have been optimized. The tested conditions are listed in table 4. The comparisons are made from the yields of the formation the ligand LA calculated for the two last steps from intermediate 4, since the mixture 5 and 5' was directly engaged in Sonogashira coupling reaction. For the calculated yields listed in table 4, the same reaction conditions for the Sonogashira coupling have been applied (the best condition is described in scheme 4 and in the next paragraph). The initial condition (Entry 1, Table 4) is inspired from the manuscript of Mélodie NOS and reported procedure. 220 The yield of the formation of ligand LA is low of 14 % yield. This could be explained by the formation of insoluble side product of oxidative polymerization. 229 To prevent the side reaction, the number of equivalents of NBS was decreased from 2.25 to 2.00 eq. and it was added in several portions (Entry 2, Table 4), but the yield was not improved. Then, bromine was used instead of NBS inspired from reported procedure. 230 Bromine was added at 0 °C, then the reaction was carried out at room temperature (Entry 3, table 4). The yield was significantly improved to 40 %, but the reaction suffers from a lack of reproducibility. Hence, the reported conditions have been modified by keeping the temperature in the temperature range -5 to 0 °C during the reaction (Entry 4, Table 4, conditions optimized during the project of resynthesis of PC). These new conditions permit to improve the yield from 14 to 41 % with a good reproducibility. The final step is a Sonogashira coupling reaction between brominated compounds 5 and 5' and trimethylsilylacetylene (TMSA) in the presence of Pd catalyst, CuI and a base. From the initial conditions,232 the yield was increased by changing Pd(OAc)2 by Pd(PPh3)2Cl2, the solvents, the base ( i Pr2NH instead of Et3N) and by heating, inspired from reported procedure 233 . Thanks to these optimizations, larger quantities of LA have been prepared for the synthesis of metallooligomer PA. It helps us to test different reaction conditions to increase the average molar mass of PA.

Synthesis of PA :

In this part, the reaction conditions have been modified to increase the average molar mass (Mn) of PA (Scheme 4).

Scheme 4: The synthesis of PA

After several attempts, the optimal condition is the use of an excess of ligand (1.8 eq. instead of 1.0 eq.) and CuI (0.5 eq. instead of 0.1 eq.) and longer reaction time (3 days instead of 1 day), Table 5. Metallooligomers with two-fold higher Mn, Mn= 23.8 Kg.mol -1 with Đ= 2.8 have been prepared (Entry 2, Table5). The metallooligomer PA has been purified on X1® bio beads. The metallooligomer formation was confirmed by 31 P{ 1 H} NMR. The spectrum represented in figure 32 displays a single signal at 3.55 ppm with a coupling constant J( 31 P-195 Pt) of 2306 Hz, which confirms the trans-geometry of the ligands in the square planar [Pt] complex. The NMR spectra of the two metallooligomers PA: short chains (Mn = 12-13 Kg.mol -1 ) and long chains (Mn=23-24 Kg.mol -1 ) are compared in figure 99. 31 P{ 1 H} NMR spectrum of PA consists of a second low intense signal at 7.5 ppm attributed to end-chain L-Pt(PBu3)2-Cl, which proves the presence of short chain metallooligomer. This signal is not present in the spectrum of long chains PA. After complexation of the ligand to Pt(II)-complex, a chemical shift of -0.38 ppm of thiophene terminated proton nearby the triple bond is observed. Therefore, the formation of PA is confirmed by the variation of 1 H chemical shift of protons from thiophene and by the comparison of IR-ATR spectra of ligand LA and polymer PA. A decrease in the vibration frequency of the band ν(C≡C) from 2140 to 2083 cm -1 is observed. This is similar to the characterizations of P1' (Table 2). Then, the mass distribution is determined by GPC. The comparison of the chromatograms of PA short chains (Condition 1) and long chains (Condition 2), represented in figure 100, shows an increase in the Mn with the application of optimized reaction conditions 2. Using condition 2, the average molar mass is increased twice to 23-24 Kg.mol -1 with Ɖ of 2.8 in comparison with PA (short chains, condition 1) (Mn= 12-13 Kg.mol -1 , Ɖ= 2.3) (Figure 100). This corresponds to chains with an average length of 17-18 repeating units in comparison to 9-10 units for PA short chains (Condition 1). Mn of PA long chains is close to those of P1' with Mn=18-19 Kg.mol -1 , Ɖ= 2.1, and 14-15 repeating units (Table 2). Moreover, the decomposition temperature of PA is tested at 5 wt % loss and compared to that of P1'. The analysis is summarized in table 6. The optical properties of ligand LA and metallooligomer PA have been investigated by absorption spectroscopy on the liquids and on thin films with the determination of wavelength onset (𝝀abs (onset) ) to calculate the optical band gap and compared to those of L1' and P1'. The spectra are represented in figure 102 and figure 103 and the data are listed in table 7.

The absorption capacity of LA was investigated with the determination of the molar extinction coefficient (ε𝝀). It is higher (4.89x 10 4 mol -1 L cm -1 , 5.02x 10 4 mol -1 L cm -1 ) than those of L1'(3.71 x10 4 mol -1 L cm -1 , 4.44 x10 4 mol -1 L cm -1 ). The comparison of the absorption spectra of the solutions in figure 102 shows a bathochromic shift of absorption band at the lowest energy from LA to PA, similar to L1', P1'. It is explained by the increase of the conjugation length after the complexation reaction. Absorptions of PA were measured on thin films to evaluate the 𝝀abs (onset) and to calculate the optical band gap (Eg opt ). The spectra of PA and P1' are compared in figure 103 and the data are listed in table 7. As expected, a bathochromic shift of 𝝀abs (onset) of 66 nm is observed from P1' to PA, which corresponds to a decrease of the optical band gap from 1.72 eV for P1' to 1.58 eV for PA. After following the first way to increase the average molar mass by carrying optimization on the reaction conditions of the dehydrohalogenation reaction, we successively obtained long chains metallooligomer PA with twice the average molar mass of PA synthesized with the initial condition. Therefore, PA was investigated in photophysics to evaluate the phototransfer and electronic transfer with fullerene acceptor (PC71BM) and to study the recombination's time.

Photophysical study of PA:

After obtaining the suitable electronic structure for electron transfer between the donor metallooligomer PA and the used acceptor PC71BM, the photophysical properties are studied for the metallooligomer by our collaborator Pr. D. Harvey from Sherbrooke University, Canada. MCzM (Figure 105) was also studied as an acceptor with PA.

Photoreductive electron transfer between PA and electron acceptor:

The objective of these studies is to evaluate the times of phototransfer between the donor such as PA and an acceptor and the time of charge recombinations.

After formation of the exciton in the donor ( 1 polymer*), an electron transfer occurs from the donor like a polymer and in our case the metallooligomer to the acceptor like PC71BM ( 1 polymer* + acceptor → polymer + • + acceptor‾ • ). Based on the investigation of P2', this process occurs in femtosecond time scale, and the recombination with the back-electron transfer occurs in picoseconds with the formation of triplet state (polymer + • + acceptor‾ • → 3 polymer* + polymer + acceptor). 234 However, fullerene acceptors suffer from low absorptivity values in the visible region, which cause small relative number of excitations generated by the direct excitation of the PC71BM acceptor. Consequently, MCzM was used as non-fullerene acceptor to overcome this potential problem in this study with PA as donor material.

The absorption, excitation and fluorescence spectra of the donor metallooligomer and the MCzM acceptor are reported in figure 106. Both the metallooligomer and the acceptor are weakly fluorescent.

Stability test:

PA discloses instability when the solutions of PA are exposed to room light or to a high intensity irradiation source. It is noteworthy that the physical parameter study was carried with fresh samples under soft power light. To study this instability, PA was dissolved in degassed CH2Cl2 solvent and subjected to an irradiation 𝝀exc = 623 nm and flux power intensity 20 times to that used in solar cell design. The Quasi-total photo conversion or polymer decomposition occurred in 10 minutes of irradiation. Hence, PA is not stable enough to be used as a donor in BHJ solar cell (Figure 107). So, these results were published in 2022 in Journal of Inorganic and Organometallic Polymers and Materials. However, due to the instability issue of PA, we followed another way to increase the average molar mass Mn, which is functionalizing of the conjugated system with a solubilizing group to enhance the solubility of the ligand and the metallooligomer. This approach was inspired from the reported work of Wong and al, 220 hence, a new ligand LB was prepared with two thiophenes functionalized with a solubilizing linear alkyl chain C12H25.

Functionalizing with solubilizing chain to increase the average molar mass:

In this part, we describe the second way of strategy 1, which aims to increase the average molar mass of the metallooligomer. Linear alkyl side chain is used as a solubilizing chain on thiophene units, which could improve the solubility of ligand LB, and the metallooligomer PB and this helps to reach higher average molar mass. Indeed, Linear alkyl chains have been chosen to maintain important aggregation with reduced π-π stacking distances for enhanced electronic mobilities. Moreover, linear alkyl side chains could be utilized to promote the nanostructural order of the active layer and further to enhance the photovoltaic performance. LB was used in dehydrohalogenation reaction for PB preparation (Scheme 5).

Scheme 5: The synthesis of metallooligomers PB

Synthesis of LB

The goal of this part is to synthesize ligand LB, that is an analog of LA, the difference is the presence of linear alkyl chain n-C12H25 on the second thiophene. The synthesis of ligand LB is inspired by the work of Zhan, Wong and al, 220 it is represented in scheme 6. It is like the route followed for the synthesis of ligand LA.

Scheme 6: The synthetic route of ligand LB

The insertion of C12H25 functionalized thiophene is made by a Stille coupling reaction between the brominated DPP containing compound 3 and the freshly prepared stannic of C12H25-thiophene. The compound 6 is isolated with a yield of 67 %. The next step is the bromination of compound 6 using the same optimized conditions applied in LA synthesis, with bromine at range temperature of -5 to 0°C. This yields to a mixture of mono-and bisbrominated compounds 7 and 7' with tedious purification. Hence, they were not separated. The last step is a Sonogashira coupling reaction between the mixture 7, 7' and trimethylsilylacetylene catalyzed with Pd(PPh3)2Cl2 in the presence of CuI and the base i Pr2NH. The ligand was isolated with a yield of 66 % in the two last steps from intermediate 6 (Scheme 6). As expected, the solubility of LB is better than for LA.

All intermediates and ligands were characterized with 1 H and 13 C NMR, ESI. HRMS and MALDI TOF were carried out to complete the characterizations of the ligands. The ligand LB was used for the preparation of metallooligomer PB.

Optical properties of LB

The absorption spectra in CH2Cl2 of the different ligands L1', LA and LB have been represented in figure 108 The comparison between LA and LB spectra shows a very small bathochromic shift in the absorption band for LB. So, there is no significant impact of functionalizing the thiophene units with a solubilizing chain on the absorption wavelength range. Hence, the optical band gap is not affected. The metallooligomer PB was synthesized according to the optimized protocol applied for long chains PA (Scheme 7, Table 8).

Scheme 7: The synthesis of metallooligomer PB

The progress of the reaction was monitored by 31 P{ 1 H} NMR. It was noticed that the metallooligomer PB was not formed at room temperature (Entry 1, Table 8). Hence, the reaction temperature was increased to 45 °C. After two hours, 31 P{ 1 H} NMR spectrum exhibits two signals at 4.8 and 3.5 ppm attributed to distinct complexes with coupling constant JPt-P= 2330 Hz for both. The purification on biobeads® X1 didn't succeed in separating the two complexes and some ligand remained evidenced by TLC monitoring. The mixture was analysed by GPC. The GPC chromatogram of PB (Figure 109) shows two main broad peaks, which evidences, the presence of several populations of metallooligomers and the majority is of ligand LB. The poor progress of the reaction for the preparation of PB even after heating could be explained by a poor reactivity during the polymerization due to the steric hindrance generated by the alkyl chain on the thiophene and butyl groups of the phosphine despite the better solubility of LB.

Figure 109: GPC chromatogram of PB

Following strategy 1, it results in improving the average molar mass of metallooligomer PA. This result was published in 2022 in Journal of Inorganic and Organometallic Polymers and Materials. But the synthesis of the desired metallooligomer PB with solubilizing chain was not succeeded. The photophysical properties of PA were studied. Nevertheless, PA shows instability to irradiation, which prevents using it as a donor material in BHJ solar cells. Hence, we focused on strategy 2 for the synthesis of a new narrow band gap DPP based metallooligomer PC. The objective of strategy 2 is to obtain a narrow band gap metallooligomer with higher stability than P2' and with easier synthesis for preparing large quantities. Synthesizing enough quantity allows our collaborator Pr. Ganesh D. Sharma to try different conditions for binary systems and to apply distinct architectures as ternary systems with two acceptors (donor/ acceptor1/ acceptor2) or as tandem solar cells.

Strategy 2: Narrow band gap metallooligomers:

In the team, a narrow band gap metallooligomer P2' was prepared by Mélodie NOS during her PhD project (2015-2018). It exhibits an electrical band gap of 1.41 eV and a wide absorption wavelength range from 550 to 850 nm. These good optical properties and suitable band's electronic structure for obtaining efficient electronic transfer explain the good performances of the BHJ solar cells. They exhibit an average PCE of 9.42 % with P2' as a donor and PC71BM as an acceptor. The modification of the organic part (Ar) of the ligand with dimers (T-DPP-T)2 permits the enhancement of the optoelectronic properties with a better PCE than P1' (PCE= 7.05 %, P1': PC71BM).

The drawbacks of P2' are instability issue of deprotected ligand L2', low Mn, difficult synthesis and difficulties to apply chemical functionalizations. 222 For that, the aim of my PhD project is to prepare a new narrow band gap metallooligomer PC by replacing the second thiophene ring of PA by 3,4-Ethylenedioxythiophene unit (EDOT).

Based on a reported work on EDOT and DPP containing conjugated polymers, 235 the insertion of EDOT moiety in the organic part (Ar) of the ligand brings benefits such as an increase in the conjugation length, providing strong electron donor character to increase the intramolecular charge transfer and leading to a narrow the band gap. 227 The presence of S…O interactions increases the planarity of the conjugated backbone. This permits to increase charge mobilities. 235 Besides, alkoxy groups of the cycle of EDOT unit increases the stabilization of the quinoid structure, which helps to decrease the band gap.

Moreover, the cycle of EDOT can easily be functionalized with a side chain carrying a function with the preparation of metallooligomer PD depicted in figure 110. This side chain permits to increase the solubility and the molecular organization of the donor, to improve the morphology of the active layer and the dissociation of excitons (Figure 110). The side chain used could be carrying an organizing group as triphenylene, 236 solubilizing group as a branched extended alkyl chain. 237 Also, the siloxane chain is interesting to improve the separation of donor/ acceptor in the active layer. 238 Moreover, polar chains like ethylene glycol could decrease the binding energy in exciton and consequently increase the exciton dissociation leading to an increase in the charge's generation. 239

Synthesis of PC:

The synthesis of PC includes the synthesis of ligand LC followed by Cu-catalyzed dehydrohalogenation reaction to obtain the desired metallooligomer (Scheme 8).

Scheme 8: The synthesis of PC

Preparation of Ligand LC:

The ligand LC is prepared in a similar strategy to that of LA and LB. EDOT unit was inserted after a Pd(PPh3)2Cl2 catalyzed Stille coupling reaction between the bisbrominated intermediate 3 and freshly prepared EDOT stannic derivative . The EDOT containing compound 8 was isolated with a yield of 67 %. The next reaction is the bromination of compound 8. It is the limiting step. The formation of the compound 9 is confirmed by 1 H NMR and mass spectrometry with the formation of insoluble side products formed from oxidative polymerization. 240 A strict control of the temperature and maintaining it in the range of -5 °C to 0 °C, in dark with shorter reaction time of 1.5 hours limit the side reaction. Compound 9 was directly engaged in the next step, which is a Sonogashira coupling reaction to install the triple bonds protected with silyl groups (TMS). Hence, LC was isolated with a good purity and a global yield of 39 % from 8 (Scheme 9).

Scheme 9: The synthetic route of ligand LC

Synthesis of PC:

PC was prepared with same reaction conditions applied for PA; conditions 1 and 2, by CuI-dehydrohalogenation reaction at R.T for three days (Scheme 10) to give a turquoise compound, which was purified by steric exclusion on bio-beads® X1.

Scheme 10: The synthesis of metallooligomer PC 2.1.3. Characterizations of PC PC formation was confirmed by 31 P{ 1 H} NMR with a signal at 2.56 ppm with JPt-P= 2317.81 Hz. An infrared spectroscopy brings out vibration frequency for the triple bond at 2078 cm -1 . The average molar mass has been evaluated in gel permeation chromatography; it is found to be Mn= 12 Kg.mol -1 with Đ= 2.06 close to that of PA (Mn=12.4 Kg.mol -1 ) using the first condition. In comparison to the previous metallooligomer P2' (Mn= 6.6 Kg.mol -1 , Đ= 11.1), it is of higher average molar mass and smaller dispersity. In our work we compared the average molar mass of PC to metallooligomer PA, it has been found that they have close values (Figure 111).

Figure 111: Comparison of GPC chromatograms of PA and PC

The decomposition temperature of PC has been tested and compared to P2' to evaluate the improvement from P2' to PC. The data from the analysis of P1', P2' and PC are listed in table 9. The optical properties of ligand LC and metallooligomer PC have been investigated by absorption spectroscopy on the liquid and on thin films with the determination of wavelength onset to calculate the optical band gap and to be compared to those of L2' and P2'. The spectra are represented in figure 112 and figure 113 and the data are listed in table 10.

The absorption capacity of LC was investigated with the determination of the molar extinction coefficient (ε𝝀). LC shows ε𝝀 ((609 nm) 4.81x 10 4 mol -1 L cm -1 , (658 nm) 5.17 mol -1 L cm -1 ) much higher than those of L2' (1.39 x10 4 mol -1 L cm -1 , 1.42 x10 4 mol -1 L cm -1 ). The comparison of the absorption spectra of the solutions in figure 111 shows a bathochromic shift of absorption band at the lowest energy from LC to PC. Moreover, PC is with higher 𝝀abs (max) of 710 nm compared to LC with 𝝀abs (max) of 658 nm. The same bathochromic shift is observed between L2'and P2' with higher 𝝀abs (max) for P2' (718 nm) compared to L2' (669 nm). This means a smaller band gap by increasing the conjugation length.

Figure 112: The absorption spectra of L2', LC, P2' and PC in CH2Cl2

Absorptions of PC and P2' were measured on thin films to evaluate the 𝝀abs (onset) and to calculate the optical band gap (Eg opt ). The spectra of PC and P2' are compared in figure 113 and the data are listed in table 10. The values of 𝝀abs (onset) are about 840 nm and 875 nm for PC and P2', respectively. So, the Eg opt was calculated with 1.48 eV for PC, which is close to that of P2' (1.42 eV). Strategy 2 is based on the insertion of EDOT, which permits a decrease in the band gap to 1.42 eV in comparison to P1' (Eg elec = 1.62 eV) and with close value to that of P2' (Eg elec = 1.41 eV). The risk of the insertion of a strong donor like EDOT is level rising of EHOMO which leads to decrease in VOC. But regarding the cyclic voltammetry analysis, the HOMO energy level of PC is slightly higher of 0.09 eV than those of P2'. However, the LUMO level of PC is slightly higher than that of P2' allowing a higher ∆E1 value (Figure 114). ∆E1 and ∆E2 are calculated according to the following equations: Based on these promising preliminary results, a collaborative project was started in 2021 between the members of the team to resynthesize the metallopolymer PC in larger quantities (300-500 mg) to fully characterize it and to study this compound in photophysics and finally to use it as a donor in BHJ solar cells. The challenge was to prepare larger quantities (to multiply the synthetic scale by 10). The re-synthesis was conducted by Jean-François Lohier, an engineer in organic chemistry and Romuald Herbinet an engineer specialized in GPC and thermal properties characterization in the team POHET at the LCMT. The collaborative work allows optimizations on the bromination and Sonogashira steps described previously (Scheme 9). This permits the increase of the yields and the purity of the intermediates. The collaboration between Jean-François Lohier and Romuald Herbinet leads to an improvement of the dehydrohalogenation step. Thanks to GPC monitoring, which leads to the increase of the purity and the average molar mass of PC (15.1 Kg.mol -1 , Ɖ = 2.5). This project leads to the preparation of 300 mg of PC. It was fully characterized in 1 H, 31 P{ 1 H] NMR, IR-ATR, GPC and MALDI-TOF. The data from cyclic voltammetry confirms the preliminary results (EHOMO = -5.27 eV, ELUMO = -3.85 eV). The photophysical properties of PC were investigated by Pr. Pierre D. Harvey.

∆E1= LUMO A -HOMO D ∆E2= LUMO D -LUMO A
During the photophysical properties investigations, the stability test shows PC is much more stable than P2' in the solid state. In addition, PC and the mixture PC/PCBM in solution are stable even after one month. Hence, by now PC is the most stable metallooligomer prepared in the team.

Based on these promising results, 150 mg from the 300 mg batch was used as a donor in BHJ solar cell with PC71BM and non-fullerenes acceptors like IT-4F and Y6, to test different ratio donor/acceptor. The SVA treatment was applied to improve the morphology of the active layer. The solar cells achieve good performances with an average value of PCE at 8.96 % with PC71BM which is close to the PCE of 9.42 % for P2': PC71BM. These performances increased significantly to 11.94 % with IT-4F and 14.12 % with Y6. It was planned to prepare ternary systems to increase the PCE. We plan to publish these results in 2023 in ACS macromolecules.

Thanks to the collaborative work, we were able to end by promising results, where PC was synthesized in large quantities with improved purity allowing the preparation of BHJ solar cells using PC as a donor material with different types of acceptors. The manufactured BHJ solar cells show good performances.

After the promising results of PC, we have decided to develop another type of metallooligomers PD with the functionalization of the cycle from EDOT moiety with side chains carrying distinct functions Y to enhance the performance of solar cells.

Synthesis of functionalized EDOT containing metallooligomers PD:

Functionalization of PD could be applied for different purposes versus the type of function Y carried by the side chain. For conjugated polymers, side chains have an effective impact on solubility, processability, intermolecular packing and an impact on the morphology of BHJ organic solar cells. 241 PD could be functionalized with a solubilizing group ( Y= alkyl chain) to increase the average molar mass, polar group ( Y= ethylene glycol) to increase the exciton dissociation, siloxane chains ( Y= SiOR) 242 which increases the D/A segregation in the active layer, and by organizing group such as Y= triphenylene to enhance the molecular organization and to increase the compatibility with the acceptor. Among solubilizing groups, we chose the extended branched alkyl chain, which favors good solubility, and promotes better aggregation with shorter π-stacking distances (Figure 115). 116) is considered as the generic and the common synthon of the two strategies and it is used for the synthesis of functionalized metallooligomer PD (Scheme 11). This unit is composed of the EDOT rings to keep the same advantages than for PC. The second component is the presence of an alkyl spacer to increase the flexibility for an enhancement of the molecular organization. The third part is the protected alcohol function OP with silyl group (P). Generation of the alcohol function after deprotection permits to graft Y functions. The last part is the chiral center, which allows preparing stereoregular metallooligomers to improve the molecular organization and to enhance the charge transport.243 (R)-EDOT-MeOR-OP is described in figure 116.

Figure 116: The descriptive skeleton of the generic synthon

The syntheses of this part were conducted by Victor Boshveski during his research project for his M2 internship (January -June 2022) period. It was an opportunity for me to train an M2 student with Cyprien Lemouchi and Loïc Le Pluart.

Preparation of the generic Synthon (R)-EDOT-MeOR-OP

Synthesis of (R/S)-EDOT-MeOH:

Due to the high cost of commercially available (R/S)-EDOT-MeOH (362 euros/g). The synthesis has been carried in four steps according to the literature starting from commercially available and cheaper 3,4-dibromothiophene (12 euros/g, Sigma-Aldrich, Meck) with optimized procedures inspired from the literature244 (Scheme 12).

Scheme 12: The synthesis of the racemic mixture (R/S)-EDOT-MeOH 13

The first step was carried according to Cu catalyzed reported procedures, 244 but the product was isolated with a yield of 10 %. So, reaction conditions have been modified by adding an excess of sodium methanoate. The reaction was monitored by TLC, sequential additions of CuO and base are required to increase the progress of the reaction. With these optimizations, the yield of compound 10 was increased from 10 % to 63 %. The second step is an intermolecular cyclization reaction between the compound 10 and (R/S)-3-chloro-1,2propanediol, activated in the presence of para-toluene sulfonic acid (p-TSA). Compound 11 was obtained with a yield of 63 %. The third step is the formation of the ester derivative 12 from sodium carboxylate to give compound 12 with a yield of 68 %. The last step is a hydrolysis reaction of the ester 12 to obtain (R/S)-(EDOT-MeOH) 13 in a good yield of 93 %.

(R/S)-EDOT-MeOH was isolated with a global yield of 25 % from the commercially available 3,4-dibromothiophene.

Synthesis of (R)-EDOT-MeOH

Stereoregular conjugated polymers have attracted attention in numerous applications. They show better optical and optoelectronic properties, and better molecular organization. 245 Therefore, it is interesting to prepare stereoregular metallooloigomers from enantiopure (R)-EDOT-MeOH. We could study the benefits of the presence of a chiral center on the molecular organization and charge transport properties. The chiroptical properties of this synthon have been investigated in the literature. 245 To study the benefits of the presence of a chiral center, we synthesized the (R)-isomer of EDOT-MeOH to be used as a building block in DPP based metallooligomer. The synthesis is inspired from the literature (Scheme 13). 246

Scheme 13: The synthesis of (R)-EDOT-MeOH 16

The synthesis of the chiral EDOT (R)-EDOT-MeOH 16 is of the same protocol used for the preparation of the racemic mixture (R/S)-EDOT-MeOH 13. The first step is a reaction between intermediate 10 and (S)-3-chloro-1,2-propandiol to form intermediate 14 with a yield of 85 %. The second step is a nucleophilic substitution to form compound 15 followed by hydrolysis of the ester 15 using basic conditions to form compound 16. (R)-EDOT-MeOH 16 is prepared with a global yield of 45 % from 3,4-dibromothiophene. The difference in the global yield between the racemic mixture and compound 16 is the use of dry p-TSA in the second step. The formation of the enantiomeric pure compounds 14 and 16 are confirmed by high performance liquid chromatography HPLC analysis carried out by Fabien Le Cavelier in LCMT laboratory. An HPLC column with chiral stationary phase has been used for the separation of the two enantiomers in the racemic mixture. The comparison of the chromatograms of the compounds 14 and 16 with the one of the racemic products confirms the enantiomeric purity of the samples with the presence of only one peak, which justifies the presence of a single enantiomer.

Synthesis of (R)-EDOT-MeO-ROP:

The aim of this part is to synthesize the generic synthon (R)-EDOT-MeO-R-OP 18. As represented in scheme 14, it is prepared from the attachment of an alkyl chain as spacer of 6 carbon atoms terminated by a protected alcohol (OTBDMS). The spacer increases the flexibility and the alcohol function generated after removing silyl group permits to functionalize EDOT with side chains and Y functions. The synthesis of a similar compound EDOT-MeO-R-OP is reported. It's a racemic sample, and the alcohol function is protected with tetrahydropyran (THP). 247 The synthetic route is illustrated in scheme 14, where tert-Butyldimethylsilyl (TBDMS) protecting group was used because it is more robust and compatible with several reaction conditions. The synthetic rout of (R)-EDOT-MeO-R-OP 18 is illustrated in scheme 14.

Scheme 14: The synthesis of (R)-EDOT-MeO-R-OP 18

The synthesis of (R)-EDOT-MeO-ROP 18 requires the preparation of a halogenated chain terminated with protected alcohol 17, which is successively synthesized with a very good yield of 98 % from reported procedure. 248 This chain was engaged in Williamson O-alkylation reaction with deprotonated compound 16. The generic synthon (R)-EDOT-MeO-ROP 18 was isolated with a yield of 71 %. However, a series of optimizations was carried out to increase the yield from 0 % to 71 %. The data of the reaction condition are listed in table 11.

For the first attempts inspired by reported examples of O-alkylation of EDOT-MeOH,249 a large excess of sodium hydride (20 eq.) has been used in THF at room temperature (Entry 1, Table 11). However, no product was obtained, and the starting material has been isolated. For next attempts, the number of equivalents has been decreased to 4 eq. (Entry 2) and to 2 eq. (Entry 3) but the reaction didn't proceed. Other experiments have been carried out with a moderate heating to 45-65 °C,250 but it failed (Entry 4). The base has been replaced by KOH, inspired from an example of alkylation of EDOT,251 only the starting material was isolated. According to alkylation of an oxazole-R-OH heterocycle, 248 the reaction has been carried with excess of NaH (10 eq.) at room temperature in DMF instead of THF and the product 18 has been obtained with a good yield of 71 % (Entry 5). After the synthesis of (R)-EDOT-MeO-R-OP, the objective is to synthesize the stannic compound to be attached to DPP intermediate by Pd-catalyzed Stille coupling reaction for applying the post functionalization strategy. Hence, it is important to work on the preparation of stannic derivatives from the protected synthon (R)-EDOT-MeO-R-OP.

Example of pre-functionalization with the direct functionalization of (R)-EDOT-R-OP with alkyl chains:

To test the first strategy of pre-functionalization represented in scheme 11, we have decided to use an alkyl chain as Y function, because it is compatible to all reaction conditions. Initially, the preparation of extended alkyl branched chains was decided to increase the solubility of n-type conjugated polymers (Chapter 3). They were prepared during M2 internship (Viktor BOSHEVSKI, January-June 2022) from reported procedures. 252 As these chains were synthesized in limited quantities (100-200 mg), they were engaged in the direct functionalization of the generic synthon. The presence of branching point induces better solubility, while the presence of a linear spacer allows good π-stacking.

Synthesis of EDOT-R-OR'

(R)-EDOT-R-OR' has been synthesized in two steps starting from (R)-EDOT-R-OP 18, the first step is deprotection of the alcohol terminal using TBAF at R.T to obtain compound 23 with a yield of 81 %. This step is followed by nucleophilic substitution of the deprotonated alcohol of 23 on the halogenated extended alkyl branched chain 22. The functionalized EDOT 24 was isolated with a yield of 63 % (Scheme 16).

Scheme 16: The synthesis of (R)-EDOT-MeO-R-OR' 24

The pre-functionalization strategy was successively applied with obtaining functionalized EDOT with branched extended alkyl chain 24. This compound is suitable to be used for obtaining a stannic derivative and then the stannic derivative could be used in Stille coupling reaction in the presence of DPP intermediate.

Example of post-functionalization with the insertion of (R)-EDOT-R-OP in the DPP containing ligand:

In case the Y function is sensitive to reactions conditions, the post-functionalization of the generic ligand L' could be carried out as represented in figure 117 to overcome these difficulties.

Figure 117: An example of post-functionalization strategy

Post-functionalization strategy consists of attaching the generic synthon (R)-EDOT-R-OP to T-DPP-T moiety, followed by a bromination reaction of EDOT moieties and then a Sonogashira coupling reaction to prepare the generic ligand L'. Then, the silyl group is removed to generate the alcohol function, which was used to attach the Y function to prepare LD. This ligand will be engaged in dehydrohalogenation reaction for the preparation of metallooligomer PD. The key step in this synthesis is the formation of the stannic derivative of (R)-EDOT-R-OP 25 (Figure 117).

The stannic derivative 25 was prepared from compound 18 (Scheme 17). It is inspired from a reported procedure. 254

Scheme 17: The synthesis of monostannic functionalized EDOT 25

The monostannic compound 25 is obtained in one step according to scheme 17. It starts with deprotonation reaction of the hydrogen in alpha position of thiophene with n-BuLi, followed by a nucleophilic substitution on tributyltin chloride to obtain the desired compound 25 with 75 % conversion according to 1 H NMR analysis. This step required an optimization, listed in table 13.

Table 13: The different conditions for the synthesis of compound 25

Entry n-BuLi(2.5M) Bu3SnCl Solvent Duration [18] mmol/mL Conversion 1 1.0 eq. 1.0 eq. THF 18 h 1.5 0 % 2 0.9 eq. 0.9 eq. THF 18 h 13 75 %

At the beginning the stannylation reaction has been tested on 1 equivalent of the base and 1 equivalent of the stannic reagent. However, the 1 H NMR spectrum showed the absence of the monostannic product. To increase the reactivity of the base, the concentration has been increased from 1.5 mmol/mL to 13 mmol/mL and the number of equivalents is reduced to 0.9 for each of the base and the stannic reactant to minimize the formation of bis stannic EDOT.

To verify the formation of the desired compound, a comparison between the 1 H NMR spectra of the starting material and the isolated compounds was made. For compound 25, the hydrogen signal at the alpha position has a chemical shift of 6.57 ppm instead of 6.3 ppm in the starting product. And the presence of the signal of the protons of butyl groups was observed around 1.5 ppm, which confirms the formation of monostannic compound 25. It was directly engaged in the next step without further purifications.

Synthesis of the generic ligand L' with the preparation of the EDOT and DPP containing intermediate 26:

post-functionalization was carried out from the generic ligand L'. It brings the advantage to be functionalized with different functions Y to prepare distinct ligands LD and metallooligomer PD. In order to prepare L', the intermediate 26 must be synthesized (Scheme 18). The generic synthon is attached to T-DPP-T moiety with a Pd-catalyzed Stille coupling reaction in the presence of dibrominated DPP 3 and the monostannic function of compound 25 according to scheme 18.

Scheme 18: The synthesis of intermediate 26

Intermediate 26 was obtained with a yield of 45 % with a Stille coupling reaction in the presence of Pd2Cl2(PPh3)2. Upon completing the reaction, a secondary product 26' was obtained with a yield of 12 %. These two compounds were characterized by 1 H and 13 C NMR.

Even with the difficulty to analyze such molecules with ASAP or ESI due to the low solubility, the molecular peak of each compound has been detected with ASAP and ESI by Karine Jarsale, LCMT, Caen. Intermediate 26 could be subjected to bromination reaction and then Sonogashira coupling reaction for the preparation of the generic ligand L' as an intermediate in LD preparation. Indeed, the expected metallooligomer from 26' could be of our interest in other type of metallooligomers with one EDOT unit per monomer to study the impact of the quantity of the organizing group.

To conclude with, (R)-EDOT-MeO-R-OP was synthesized as a generic synthon for both pre-and post-functionalization. It was successively functionalized with extended branched alkyl chain to obtain (R)-EDOT-MeO-R-OR' 24 as a key step in pre-functionalization strategy. In addition, (R)-EDOT-MeO-R-OP intermediate was directly used in the formation of stannic derivative 25. Intermediate 25 was integrated in the preparation of a generic ligand L' using a Stille coupling reaction, which could be followed by bromination reaction and Sonogashira coupling. This is as an example of a post-functionalization strategy.

Conclusion and Perspectives:

The main objective of the work demonstrated in chapter 2 is decreasing the optical band gap of metallooligomers synthesized in the team to increase the absorption wavelength range and to decrease energy losses. Increasing the conjugation length, changing the nature of organic part of the ligand and improving the planarity of the conjugated system backbone are of the methodologies applied. Therefore, two strategies were applied to enhance optical and optoelectronic properties of the metallooligomers and increasing the absorption wavelength range. The first strategy aimed to insert two thiophenes with the preparation of PA. We succeeded to obtain PA with an increased absorption wavelength range compared to P1' and with an increased average molar mass with optimization of the reaction condition of dehydrohalogenation. The insertion of solubilizing chain on thiophenes could increase the solubility of the ligand LB, but PB was not isolated because we faced reactivity problems. Concerning the second strategy, we successively obtained a new metallooligomer PC. This strategy aimed to overcome the drawbacks of a previous metallooligomer P2' and mostly the instability issue of the deprotected ligand L2' and the difficulties of the synthesis. It is applied by the insertion of strong donor (EDOT), which can play a remarkable role in improving the planarity of the backbone of the conjugated system and consequently can increase the absorption wavelength range of the obtained metallooligomer. This strategy results in a low optical band gap comparable to P2', but PC exhibit a remarkable good stability and it is prepared with easier synthetic route (Figure 118). Thanks to the collaborative project with Jean-François Lohier and Romuald Herbinet, 300 mg of PC was resynthesized with improved purity. This permits its investigation in Photophysics and its use as a donor in BHJ solar cell. The highest performances reach 15.12 % with the acceptor Y6 with an average value of 14.12 %. This good result will be published soon in ACS macromolecules.

Hence, PC is considered now as a reference for the next generation of DPP based metallooligomers accompanied with EDOT. Its performances could be enhanced with the functionalization of EDOT with side chains and functions Y. We have tested two strategies of pre and post functionalization to prepare these functionalized metallooligomers PD. Some intermediates of functionalized EDOT have been already synthesized.

In perspectives of this part, the major goal is to resynthesize the intermediate 26 to be used as a donor unit in the preparation of functionalized EDOT contained metallooligomer PD. So, the distinct side chain could be grafted by applying post-functionalization strategy to have an impact on the molecular organization of the obtained metallooligomer (Figure 119) and on its optoelectronic properties, to enhance solar cell performance.

Scheme 19: The synthesis of new type of metallooligomers using one unit of EDOT per monomer as 26' intermediate

I. Introduction:

Electron-deficient or n-type polymers have high electron affinity value due to a low lying LUMO (Lowest Unoccupied Molecular Orbital), which allows negative charge transport. It is crucial of importance to develop efficient ones to be used as semiconductors for n-type OFET (Organic Field Effect transistors) application and as conducting polymers, after a doping process, for n-type materials preparation into organic thermoelectric (OTEs) devices, when they are associated to counterpart p-type materials (Figure 120). However, n-type polymers are still rare because of their difficult synthesis, poor solubility and lower performances compared to p-type (donor, giving electron, hole transport). The greatest limitation is the lack of the stability of n-type polymers to O2 and H2O, which decreases charges transport time limit. One strategy to overcome these limitations is lowering the LUMO level. Therefore, it is important to increase the electro-deficient nature of the conjugated polymer and to improve its π-stacking of the chains. The narrow band gap of these polymers is an additional advantage for doping step effectiveness and to develop ambipolar OFET,255 the greatest advantage is the use of a single material for both holes and electrons transport. Nowadays, thermoelectric materials attract widespread attention because they can generate electricity from gradient temperature. They can increase renewable energy production part by recycling heat loss from human activity (e.g., industrial activity).

Over the history, in 1794, the first hints of thermoelectric effect were observed with Alessandro Volta's work. However, the story of thermoelectric devices started with the discovery of Thomas J. Seebeck effect in 1821, where he noticed circuit made between two unlike metals with different temperature. Many materials have considered useful for thermoelectricity generation. Starting with the inorganic materials, they are of three main categories: metal, intermetallic system, and metallic oxide. The first semiconductors and conductors used were based on metals such as copper and iron. The next generation in the 20 th century was using materials as ceramics and composites. 256 However, among the intermetallic system the best thermoelectric material is bismuth telluride Bi2Te3 257 and some of its alloy. 258,259 These materials are the most efficient at near room temperature and up to 100 °C. Indeed, it is the only material utilized and well-tried in commercially available converters with high performance calculated by figure of merit (ZT), which is with values between 1 and 2 for both n-type and p-type materials. 260 Recently, organic semiconductors have been used in thermoelectric devices.

Principle of thermoelectric devices:

There are two modes of function for thermoelectric device. 261 It is used as a power generator with Seebeck effect and as a refrigerator device with Peltier effect according to the configuration of the system (Figure 121).

Figure 121: The different function principles of thermoelectric device according to their fabrication form

Seebeck effect is used in thermoelectric generators that work as heat engines to produce electricity from heat, which could be recycled from heat generated from human activities (transportation, industrial activity, …). Peltier effect is used to form a refrigerator. In my PhD project, we focus on Seebeck effect.

Thermoelectric device consists of a pile made up of a number of two types of materials pairs: n-type and p-type (Figure 122). These materials are connected in series with conductors. The difference in temperature between the two conductors allows the generation of electric potential. The sum of these potentials is known as electromotive force. Increasing the number of pairs leads to increase in the electromotive force.

Performance of thermoelectric devices:

The energy conversion energy efficiency of thermoelectric device can be estimated by dimensionless figure, the figure of merit ZT with the equation below: 262 Where, S is the Seebeck coefficient, 𝝈 is the electrical conductivity. 𝝆 is the electrical resistance. T is the absolute temperature between the cold side and hot side K is the thermal conductivity between the cold side and hot side Z takes into consideration the electrical resistance of the thermoelements in series (R) and thermal conductivity of thermoelements Connected in parallel (K). 263

𝒁 = 𝑺 𝟐 𝑹𝑲

The electrical conductivity is determined with σ =n e μ, where e the charge carrier, n the density of charge carrier and μ carrier mobility.

After calculating the Seebeck coefficient and electrical conductivity, power factor (PF) can be calculated. Over the past years, scientists are working to manage increasing the ZT values of thermoelectric devices. Therefore, based on the figure of merit, the aim is to meet three qualitative criteria: high Seebeck coefficient, high electrical conductivity and low thermal conductivity to obtain high temperature difference between the two conductors and low electrical resistance for large circuit current. 264 On the other hand, the increase in electrical conductivity usually is followed by an increase in the thermal conductivity. Moreover, if the electrical conductivity sharply increased, the Seebeck coefficient drops as summarized in the graph below: The current applied strategy for high performance thermoelectric materials is to develop materials with high electrical conductivity and low thermal conductivity. Typically, enhancement of electrical conductivity is by increasing n using doping technique. The first type of materials is based on inorganic compounds (metals, intermetallic system, and metallic oxide). Bismuth telluride Bi2Te3, and more recently, silicon are among the high performance materials, for thermoelectric (TE) applications near room temperature. The best performing Bi2Te3, typically, p-type alloys exhibit high ZT of 2.42 at 700 K, while n-type Bi2Te3 alloys are of lower values due to higher thermal conductivities. Concerning silicon (Si), it is a tetravalent metalloid, which is recently studied in TE industry, when it is used in the form of nano-wires, the ZT value is around 1 at 200 K. 266 SnSe crystals are among type inorganic materials that shows good thermoelectric performance, where it allows obtaining the highest ZT value so far of 2.62 at 923K. 267 Despite the high ZT values of inorganic materials, they suffer inherent disadvantages such as rarity, toxicity, poor processability and expensive manufacturing. Also, this type of materials requires high operation temperature that is generally above 200 °C. 268 Therefore, nowadays, the current strategy is to decrease the thermal conductivity with porous materials preparation like the preparation of Bi2Te3 nanotubes developed in the team with Aigerim 's PhD and publication of an article.

PF = S²σ

Another strategy is the use of doped organic conjugated polymers. They are good candidates to overcome the disadvantages of inorganic materials. Currently, doped conjugated polymers show low thermal conductivity, but also low electrical conductivity. Hence, the aim of researchers is to increase the electrical conductivity.

Conjugated polymers attract attention for the preparation of p-and n-type materials for OTE applications because they have low thermal conductivity low-cost fabrication and good mechanical flexibility. They are semiconductors and reach a conductive state after a doping process. Doping process is an electronic transfer between a doping agent and the conjugated polymer and it is of two types: p-type and n-type doping. The "p-doping" is an oxidation of donor conjugated polymer, and the "n-doping" is the reduction of an electrondeficient polymer. The efficiency of doping depends on the ionization potential (IP) value for p-type doping and on the electron affinity (EA) for n-doping. Hence, the doping efficiency is affected by the energy bands levels of the conjugated polymer. So, doping process could be enhanced by tuning the energy levels by modifying the structure of the conjugated polymer for enhanced electronic transfer. In this thesis, we are interested in n-doping of conjugated polymers. The first reported high conductivity was after doping of trans-polyacetylene using naphthalenide of about 80 S cm -1 in 1978. 269 However, they have lower electrical conductivity. So, the challenge is to increase the electrical conductivity. One strategy is to increase charge mobility by improving the molecular organization of the polymer with edge-on π-stacking orientation and better π-stacking of the chains.

In the literature, we can identify the best p-type and n-type doped conjugated materials for thermoelectric applications.

properties such as low density, low cost, easy synthesis and processing. 270 P-type conjugated polymers, exhibit low thermal conductivity between 0.11 and 0.4 W/mK, and after the doping process an electrical conductivity from 10 -16 to 10 -5 S.cm -1 with power factor in range of 10 -6 to 10 -10 Wm -1 K -2 . 271 One of the highest ZT values obtained using organic material is 2.17, which is obtained at 45 K using polyaniline conducting polymer (PANI) doped with sulfonic acid due to the giant Seebeck coefficient up to 0.6 V/K. 272 The first thermoelectric device based on PEDOT was fabricated in 1988, where PEDOT is a member of polythiophene derivatives used as p-type conducting material. 273 In 2011, PEDOT doped with iron(III) p-toluenesulfonate (PEDOT: Tos) achieved the highest power factor over 300 μW•m -1 and low thermal conductivity of 0.37 W m -1 K -1 leading to ZT of 0.25 at room temperature. 274 The system PEDOT doped with polystyrene sulfonic acid (PSS) (PEDOT: PSS) is famous with their high electrical conductivity and good stability to water and oxygen. In 2013, a higher power factor of 469 μW•m -1 has been reported and ZT of 0.42 at room temperature with (PEDOT: PSS) system by mixing DMSO organic solvent to commercial PEDOT: PSS. 275 Among the p-type conjugated polymer with good power factor, there are PTbTTVT and PTbTTVT-F. They are thieno(3,4-b))thiophene derivatives TbT. PTbTTVT has electrical conductivity of 180.7 Scm -1 , Seebeck coefficient of 17.7 μV1.K -1 and power factor of 5.6 µWm - 1 K -2 . PTbTTVT-F is with slightly higher power factor of 7.2 µWm -1 K -2 with electrical conductivity of 111.1 Scm -1 , and Seebeck coefficient of 25.5 μV1.K -1 with CuTFSI dopant (Figure 124). 276 In 2019, a selenium substituted DPP polymer PDPPSe-12 (Figure 124) has been developed with high performance. After doping with FeCl3 to reach ZT about 0.25 at RT with high electrical conductivity of 997 S cm -1 , Seebeck coefficient of 62.3 μV1.K -1 , and high-power factor of 364 μV1.K -1 . 277

N-type conjugated polymers for OTHEs:

N-type counterparts are still rare and suffer from poor thermoelectric behavior due to inefficient doping process or too low conductivity. Most n-type conjugated polymers are of insufficient air and water stability, which restrict them from being efficient under ambient conditions. However, it is well-known that the stability of n-type conjugated polymers strictly related to low LUMO level. 278 Usually conjugated polymers with good charge mobility are used in organic field effect transistors and as n-type materials after doping in organic thermoelectrics.

Therefore, in this thesis we are more interested in the synthesis of stable n-type conjugated polymers with good conductivity. N-type conjugated polymers with low LUMO level are essential for n-type organic field effect transistors and for obtaining n-type thermoelectric materials with high stability and an efficient doping process. The main parameters that must be considered in choosing the building block of n-type conjugated polymers is the deep LUMO level below -4.9 eV, 279 which is required to avoid the electrochemical oxidation by H2O and O2. The second parameter is the planarity of the backbone. Furthermore, the most promising strategy to achieve low band gap polymer is to alternate donor (D) and acceptor (A) monomers because of the frontier orbitals hybridization effect. Electro-deficient feature increases with a low lying LUMO level that depends on acceptor's nature.

Perylene bisimide (PBI) is among the most promising candidate for molecular design and achieving high performance requirement. 280 Naphthalenediimide (NDI) is well-known electronic material, which can be subjected to molecular modifications to yield cores as Naphtho dithiophenediiide (NDTIs), which is one of lowest LUMO level compounds (-4.0 eV) and small band gap around 2.1 eV with attractive electronic and optical properties, which make it promising candidate as building block for n-type conjugated polymers. 281 Bithiophene 278 H. Yao, Z. Fan, H. Cheng, X. Guan, C. Wang, K. Sun, J. Ouyang, Macromol. Rapid Commun., 2018, 39, 22 279 Y-Q. Zheng, T. Lei, J-H. Dou, X. Xia, J-Y. Wang, C-J. Liu, J. Pei, Adv. Mater., 2016, 28, 7213-7219 280 R. Schmidt, J. H. Oh, Y-S. Sun, M. Deppisch, A-M. Krause, K. Radacki, H. Braunschweig, M. Konemann, P. Erk, Z. Bao, F. Wurthner,J. Am. Chem. Soc., 2009, 131, 17, 6215-6228 281 Y. Fukutomi, M. Nakano, J-Y. Hu, I. Osaka, K. Takimiya, J. Am. Chem. Soc., 2013, 135(31), 11445-11448 imide (BTI) and its derivatives are another building block have been developed as promising acceptor units (Figure 125). 282 Other families are used as a core for n-type conjugated polymers benzodifurrandione (BDFD) 283 and benzodithiophenedione (BDTD) (Figure 125). 284 NDI based D-A copolymers are widely investigated due to the coplanarity of the building block unit and the high electron affinity. Several NDI derivatives have been synthesized with different donor units resulting in low LUMO levels with the lowest value of -4.46 eV and small band gap of 1.55 eV with thiophene units. However, the smallest band gap of 1.28 eV was achieved using benzodithiophene as a donor unit with LUMO of -4.42 eV. In 2020, a family of NDTI based conjugated polymer has been developed with low LUMO level below -4.0 eV (Figure 126). 285,286

Figure 126: N-type conjugated polymers based on NDI and NDTI units

Poly(p-phenylene vinylene) (PPV) derivatives are based on benzo[1,2-b:4,5-b′]difurran-2,6-dione (BDFD) as acceptor unit, they are nearly of torsion free backbone, where the fused electron deficient rigid structure lead to less conformational disorder, low LUMO level up to -4.49 eV and a very narrow band gap of 0.89 eV with electron mobility of 0.16 cm 2 V - 1 s -1 and high electrical conductivity of 1.1 S cm -1 and power factor up to 1.96 µWm -1 K -2 and then LPPV conjugated polymers show excellent air stability. 287 FBDPPV 288 is one of the n-type conjugated polymers with highest power factor up to 28 µWm -1 K -2 and high electrical conductivity of 14-22 S.cm -1 with LUMO level of -4.17, which synthesized by the group of Pei. These n-type conjugated polymers are used in THEs (Figure 127). In the literature, benzo[1,2b:4,5-b′]-dithiophene-2,6-dione (BDTD) is a promising acceptor since it leads to polymers with LUMO levels lower than -4.00 eV. Hence, these polymers show the best electron mobility (μe) with high air stability and high TE performances (Figure 127). 283 Figure 127: The structure of LPPV and FBDPPV conjugated polymers BDTD based conjugated polymers were used in OFETs applications, as example BDTD-4T with LUMO level of -4.04 eV, small band gap of 1.16 eV and ambipolar behavior with an electron mobility of 0.30 cm 2 V -1 s -1 . 59 Another BDFD based conjugated polymer which owns low lying LUMO level are BDOPV. 289 This type of conjugated polymers shows high electron mobility in their initial state before the doping process; Therefore, they are applicable in n-type field effect transistors with LUMO level of -4.15 eV and 1.57 eV band gap with an electron mobility of 1.74 cm 2 V -1 s -1 . The addition of fluorine atoms FBDOPV 279 leads to high apparent electron mobility up to 14.9 cm 2 V -1 s -1 . Moreover, the fluorine atom leads to a lower LUMO of -4.32 eV keeping the band gap of the same value. 279 These n-type conjugated polymers are used in OFET (Figure 128). N-doping of conjugated polymers is when the dopant plays the role of a donor, so it donates electron to the LUMO level of the n-type conjugated polymer; therefore, creating electrons. As examples of dopants, there are the small atoms like alkali metals such as Lithium, cesium and Lewis acids. However, small molecule dopants can diffuse and then provoke device instability. Therefore, using large and aromatic molecules as good as donor are more efficient in the preparation of stable devices, but large enough not to diffuse in the thin film neither to act as a trap, where they must be allowed to inject an electron to the LUMO level of the conjugated polymer. Hence, the HOMO level must lie above the LUMO of the matrix. 290 This type of doping is still complicated due to the limited molecules combining the stability with appropriate high LUMO state compared to the organic conjugated polymers because the stability of the dopant against oxidation decreases as the HOMO level increases. N-DMPI-H represents the state of art as n-doping reagent, which is widely used in ntype conjugated polymers because of its high doping efficacy. 293 In contrast, TAM even has smaller size and consequently it is highly miscible with cycloalkyl edge increasing the side chain affinity, after ionization it has " Y-aromaticity" that reduces the π-affinity, while N-DMBI + have large π-system and molecular volume resulting in a potential overlap of frontier orbitals. Even though the TAM+ display dramatic effects on the conformation of the doped conjugated polymer due to its motif structure. In table 14, there are examples of the effect of dopant on the thermoelectric properties of two of the best conjugated polymers. Till now there is no clear explanation concerning the doping stage. It is still affected with different parameters rather than the structure and size, where the doping percentage is quite difficult to be expected depending on the conjugated polymer backbone.

Lowering the LUMO level of the conjugated polymers is an important factor to have efficient doping. 295 In addition, launching electron withdrawing groups is widely used strategy to lower the LUMO level for high electron mobility n-type conjugated polymers. 296 Doping is a way to increase the conductivity in conjugated polymers for thermoelectric materials, but it is not enough to achieve high conductivity. Increasing the charge carrier transport is a must for further enhancement in the electrical conductivity and consequently the power factor.

Increase the charge carrier transport:

After the generation of charge carrier via doping process, the charge carrier transport has a significant effect on the electrical conductivity, where the transfer of polaron is in two ways. Intrachain transport that is the major and strongly related to the planarity of the conjugated system. And interchain transport off carriers that is forcefully correlated by the morphology and microstructure in the film state with the aggregation of the conjugated polymer. One of parameters leading to strong π-π stacking and aggregation is long πconjugated backbone. Here there are three main criteria to follow:

• Planarity of the conjugated backbone to increase the delocalization of intra chain transport. • The morphology and microstructure tuning to enhance aggregation.

• High molecular weight of the conjugated polymer.

Planarity

Donor-acceptor conjugated polymers suffer of large torsion angles between the two building blocks, which restrict the planarity and thus the localization of polaron in the backbone and consequently the interchain transport is blocked. 297 Therefore, maintaining planarity is an urgent need for high charge carrier transport. polybenzimidazobenzophenanthroline BBL is an example of a torsion free backbone resulting in high conductivities up to 2.4 S.cm -1 . 298 Another example is LPPV that is nearly torsion free with electrical conductivity of 0.6 S.cm -1 after 76 days under ambient conditions (Figure 130).

Figure 130: Examples of n-type conjugated polymers with high planarity

The second parameter quietly linked to the increased conductivity is the suitable molecular morphology of the conjugated polymer for thermoelectric device.

Molecular morphology:

Another issue is the morphology of the conducting polymer, for instance, it is common understanding that conjugated polymers with a pseudo straight line backbone can be arranged with edge-on orientation and show high electron mobilities in organic thermoelectric (Figure 131).299 In the work of Pie, they studied the relation between the thin film morphology and the thermoelectric performance. 283 They used FBDPPV as n-type conjugated polymer and N-DMBI as a dopant. Grazing incident wide-angle X-ray scattering (GIWAXS) is one of the methods used to study the morphology. In this study, it has been noticed the role of dopant is further than enhancing the charge carrier but also it affects the molecular packing of FBDPPV. The use of suitable proportion of the dopant improves the molecular packing and consequently the charge carrier is increased (Figure 132). However, changing the percentage of dopant used has an impact on the orientation of the π-π stacking between face-on and edge-on orientation.

Average molar mass:

The last critical factor will be explained, which the mobility critically linked to is the molecular weight. 301 Neher and al 302 have demonstrated that average molar mass has a dominant effect on the mobility. They have concluded that the mobility increases as the average molar mass increases even with reduced crystallinity. This could be explained by better interconnectivity within the polymer with higher average molar mass. However, for lower average molar mass, the molecules are more like isolated microstructure. Moreover, it has been obtained that charged polarons are delocalized over several chains unless for low average molar mass the degree of polaron delocalization is lower, which explain the effect of average molar mass on the charge mobility. As an example, DPP-DTT based polymer have been synthesized with high average molar mass of 110 Kg.mol -1 , which exhibits a very high mobility up to 10.5 cm 2 V -1 s -1 contrary to low average molar mass polymer with mobility of 1 cm 2 V -1 s -1 . 303

Enhance the device stability:

The stability of conducting polymers is challenging parameter. Until now doped n-type conjugated polymers are still of poor stability. This parameter is divided into two principles: the stability of the polymer to chemical reactions and the electrochemical stability. 304 Water and oxygen are the main active components in the air. It should be noted that p-type polymers can accept electrons; therefore, they play the role of oxidation agent while n-type can donate an electron and then they play the role of reducing agent. Hence, one way to enhance the stability is lowering the LUMO level of n-type doped conjugated polymers. A comparison between PNDIT2 and 2S-trans-PNDIT2 with -3.75 eV and-3.96 eV as LUMO level respectively, it showed enhanced stability to the lower LUMO level in 2S-trans-PNDIT2 that permits electron to relax on energy level less subjected to a redox process under ambient conditions (Figure 133). 305 Another way to improve the stability is to prevent the trapping species from reaching the charge transporting area of the polymer, where the mobile electrons are thermodynamically unaffected by trapping. This could be achieved by the water and oxygen exclusion by using molecular semiconductors packed in in sufficiently dense motif to resist the penetration by these species or via appropriate encapsulation keeping the device under inert atmosphere. 306 Conjugated polymers usually are made up of a core and side chains, these chains have an impact on the solubility of the conjugated polymer, intermolecular packing and optoelectronic properties. 307 Side chain engineering is a simple and effective method to tailor the conjugated polymer without changing the core unit. They are believed to have interchain aggregation in solution, which could play a critical role in crystallization. Knowing that, side chains might provide a way to tune the interchain interactions of conjugated polymers, so, it affects the solution-state aggregation. Strong intermolecular interactions allow the conjugated polymers to have pre-aggregates in solution. 308 The packing of conjugated polymers depends on several parameters according to the pre-aggregation mechanism. However, pre-aggregation mechanism is affected by several parameters such as solvent, dissolution temperature, and solution aging time, bulkiness of the side chain, and interactions between the polymeric chain, polymer and solvent and polymer and the substrate. 309 So, it is still difficult to forecast the type of molecular organization by only choosing the type of the side chain. The choice of our chain is based on reported examples, which exhibit an increase of charge transport, but the comparison is limited because the polymer backbone is different. We are more interested in studying the impact of linear, branched extended alkyl chains and perfluorinated alkyl chains.

Alkyl side chains:

Alkyl side chains are the key factor affecting the solubility and the self-assembly of a conjugated polymer. It has been established to take part in intermolecular interactions and supramolecular self-assembly. 310 The position of the alkyl side chain can affect the optoelectronic properties because it could generate steric hindrance and decrease the planarity of the polymer. Thomas Heiser and al prepared two polymers with alkyl chains at different positions a and b, illustrated in (Figure 134). For position b the distance between the R chains is larger than in the position a, which decreases the steric hindrance. This agrees with absorption spectroscopy data. For the position b, the absorption band at the lowest energy is red shifted in comparison to those of position a. In position b, the backbone of the polymer is less sterically twisting and therefore enhanced coupling between the donor and acceptor units and increased charge transfer, which favors the reduction of the band gap. Another parameter has been tested is the length of the linear alkyl side chain, however, no significant impact on the absorption peaks. Hence, the length of the alkyl side chain does not affect the band gap. Replacing the linear position at b position by a branched chain had blue shift due to the more steric hindrance. On the other hand, the conjugated polymer with linear chain results an aggregation in solution designating the lower polymer solubility. 311

Figure 134: Examples of conjugated polymers with different alkyl side chain

Therefore, the position of the side chain has an influence on the HOMO and LUMO levels of the conjugated polymer, the impact was more on the HOMO level that was increased by 0.34 eV in b position. And the change of the type affected the solubility and the degree of aggregation, while the change in the length almost with no impact on the absorption spectra.

In 2013, a work has been carried to see the impact of utilizing different solubilizing groups on the charge transport and thin film morphology. Branched alkyl side chains increase more the solubility of the polymer than linear ones, but the steric hindrance generated by the branching point nearby the conjugated backbone of the polymer could cause torsion/binding of the chain with higher energy disorder and larger π-π spacing into the packing. This is detrimental to high charge transport. However, linear alkyl chain, less bulky leads to more ordered structure with shorter π-π spacing and hence better anisotropic transport as reported on the work of Thomas Heiser and al. (Figure 135a). 312 Besides, linear chains have a lower solubilizing effect than branched ones, but this increases the pre-aggregation mechanism speed, which favors the packing of the chains with an edge-on orientation. 313 It is beneficial for the enhancement of charges transport. This is illustrated by the reported work of Fréchet and al with the preparation of n-C16H33 linear chain functionalized DPP-containing polymers. Polymers with linear chains exhibit lower solubility and an edge-on orientation with higher a degree of crystallinity and shorter π-π spacing. Hence, their hole mobility is twice higher than for branched chains functionalized (Figure 135b). So, linear alkyl chains are interesting side chains to trigger good molecular organization and suitable packings to reach efficient charge transport. But they can lower the solubility of the conjugated polymer.

Therefore, keeping a suitable molecular organization and having a good solubility of the polymer is a challenge for the researchers. One solution is the use of branched extended alkyl chains. They are composed of a linear spacer terminated by a branched chain. The increase of spacer length (number of carbon atoms n) enables move away bulky branching point, which helps for the improvement of the aggregation and to guarantee a good solubility with the branched alkyl part. They could trigger a preferential edge on orientation with an electron mobility of 14.9 cm 2 .V -1 s -1 as reported by the group of Pei and al. 279 However, it's difficult to predict the molecular organization like the π-stacking orientation because of the influence of several parameters like the length of the spacer, the length of alkyl branched chains, the position of this chain on the conjugated backbone and their number per repeating units. This could lead to detrimental orientation face-on or usually to a mixture of edge-on and face-on orientations. Optimizations are required to select this chain according to the type of conjugated polymer.

The length of the linear spacer and so the position of the branching point have an impact on the molecular organization. As illustrated by the work of Pei and al with the preparation of F4-BDOPV polymers. They correlate the enhancement of the mobility with the increase of the spacer length, number of CH2 before the branching point from 1 to 5 (Figure 136a). The three polymers with different branching point show similar 2 theta, which reveals similar lamellar distance due to the same total length of the three branched alkyl chains (Figure 136b).314

Figure 136: (a)F4-BDOPV polymers and their electron mobility, (b) the PXRD data of the different polymers

Another example from the work of Jian Pie group about the preparation of isoindigobased conjugated polymers (IIDDT) for better understanding of maintaining planarity, aggregation, and solubility. Four conjugated polymers with different branched alkyl chains have been synthesized IIDDT-C1, IIDDT-C2, IIDDT-C3 and IIDDT-C4. The different alkyl chains were attached in the same position, their difference in the number of CH2 in the spacer (Figure 137). IIDDT-C3 and IIDDT-C4 showed a red-shifted absorption band at lowest energies. This could be attributed to a better planarity of the conjugated backbone or/and an improvement of chains aggregation with shorter π-π spacing. These observations are in correlation with GPC analysis that showed some aggregation for these two conjugated polymers with longer spacer. It has been noticed, when the branching point is away of the backbone (IIDDT-C4) the π-π stacking distance decreases from 3.57 to 3.75 Å. Moreover, the length of the spacer affects the molecular organization. The XRD measurements show an edge-on orientation of the chains stacking for IIDDT-C3 but a face-on orientation for IIDDT-C2 and IIDDT-C4. As expected, the highest hole mobility of 3.62 cm 2 V -1 s -1 is obtained for IIDDT-C3 with edge-on orientation (Figure 137). This example shows that with one chain it is difficult to forecast an edge-on orientation. For one type of conjugated polymer, an optimum length of the spacer must be found to favor this orientation. However, these examples are a guideline, but it is important to test several branched extended chains with different length of the spacer and of the terminated branched chain. Usually a mixture of face-on and edge-on is obtained.

Moreover, the density of the alkyl side chain has an impact on the overall conformation, where the decrease in the side chain grafting along the polymer backbone form helicoidal form instead of lamellar structure and then give rise to face-on orientation that is unfavorite for thermoelectric devices. 316 Therefore, the position of the side chain has an influence on the HOMO and LUMO levels of the conjugated polymer, the impact was more on the HOMO level that was increased by 0.34 eV in b position. And the change of the type affected the solubility and the degree of aggregation, while the change in the length almost with no impact on the absorption spectra.

Side chain is not limited with alkyl chains, perfluoroalkyl side chains attract the attention for conjugated polymers used as n-type materials in organic thermoelectric materials and organic field effect transistors.

Perfluoroalkyl side chains:

Perfluoroalkyl chains are of our interest to integrate it to the backbone we have as a side chain attached to the organizing group in the conjugated polymer since the presence of fluorine atoms gives unique properties, such as hydrophobicity, rigidity, thermal stability, chemical/oxidative resistance and an ability to self-organize, 317 which make them promising solubilizing groups. Fluorinated alkyl side chains have a closely packed structure which prevents the diffusion of water and oxygen into films. Consequently, they permit the stability under ambient condition. Moreover, fluorine atoms allow the presence of fluorophobic interactions leading to self-organized architectures, which could enhance the charge transport. 318 In a literature study, semi-fluoroalkyl side chains have been introduced to an electronaccepting naphthalene diimide (NDI) unit alternated with an electron donating unit such as bithiophene T2 and thienylene-vinylene-thienylene (TVT) giving two semiconducting polymers PNDIF-T2 and PNDIF-TVT (Figure 138). The two polymers show air stability and high crystallinity due to self-organization leading to rigid polymer backbone. The electron mobilities are up to 6.50 and 5.64 cm2 V -1 s -1 for PNDIF-T2 and PNDIF-TVT, respectively, which are higher than those of PNDI2OD-T2 (0.1 cm2 V -1 s -1 ) and PNDIDT-TVT (1.84 cm2 V -1 s -1 ) (Figure 138).319 139). 320 The presence of fluorinated terminal fragment might allow a higher degree of organization.

Figure 139: The structure of Perfluoroalkyl and ether perfluoroalkyl PEDOT and ester analogue

PCTV-BTzF is a D-A conjugated polymer with semi-fluorinated alkyl side chain with good solubility in common organic solvents (figure 140). 321 The semi-fluorinated chain allows the self-organization behavior by self-aggregate between the alkyl part and fluorocarbon part. Also, it affects the molecular orientation with planar back structure. Moreover, due to the fluorophobic effect and self-segregation of the chains, strong self-aggregation is induced leading to small π-π stacking distance (3.62 Å).

Figure 140: Conjugated polymer with superior self-assembly

The presence of fluorinated side chain shows superior self-assembly morphology with small π-π distance after thermal annealing, which could be due to the repulsive interaction of hydrocarbon and fluorocarbon in the solvent with no dramatic impact on the LUMO and HOMO levels compared to the non-fluorinated polymer. Therefore, fluorinated side chains weakly change the electrochemical properties but widely affect the morphology and the stability of a conjugate polymer. Polar side chains such as oligoethylene glycol side chain increase the compatibility between the conjugated polymers and dopant used in thermoelectrics through enhancing miscibility between them. 292 Then, polar side chains can allow complete p-doping efficiency of conjugated polymers such as polythiophenes by F4TCNQ leading to high conductivity of 100 S cm -1 for a low dopant fraction (10 %) with thermal stability. 322 Naphthalenediimide-bithiophene copolymer p(gNDI-gT2) is a structural analogue of P(NDI2OD) functionalized with oligoethylene glycol side chain (Figure 141). A comparison with P(NDI2OD-T2) with non-polar side chains shows that the polar oligoethylene side chains prevent the aggregation of dopant (N-DMBI) up to a concentration of 20 mole %, which proves the enhanced polymer/ dopant miscibility. The obtained electrical conductivity is above 10 -1 S cm -1 , which is at least 2 orders of magnitude higher than P(NDI2OD-T2). 323

Figure 141: The structure of P(NDI2OD-T2) and its structural analogue p(gNDI-gT2)

N-type conjugated polymers have apportioned considerable improvement for many applications other than thermoelectrics such as n-type organic field effect transistors (OFETs).

Organic field effect transistors:

The concept of field effect transistors was proposed by 1930. 324 Then, in 1986, Tsumura and al have discovered the organic field effect transistors OFETs. 325 Figure 142 shows the structure of an OFET device. In a context of semiconductors worldwide shortage, it is crucial to develop efficient organic semiconductors as transistors or sensors instead of traditional ones (silicon, metals or metal oxides) because of low cost, less toxicity, light weight and mechanical flexibility, low operating voltages, ease of low temperature yet large-scale manufacturing and, they have good compatibility with large-area and flexible substrates/materials. 220,326 An Organic field-effect transistor (OFET) is a switching device, basically from a gate electrode, a dielectric layer, source and a drain electrode; Both are in contact with an organic semiconductor (OSC) layer, whose charge density is modified by an electric field applied between the semiconductor and a gate electrode (Figure 142), with no requirement for doping process. According to the position of the gate and the electron semiconductors, four configurations can be obtained.

To obtain the ideal n-type OFET, high electron affinities correlated to the lowest LUMO level are required for better charges injection under ambient conditions with high electron mobility. 227

Principle of OFET:

In a field effect transistor, when the gate voltage VG is applied, the free charges are produced between the semiconductor and the dielectric layer. In addition, a small source/drain voltage VDS is formed leading to a current in the channel controlled by VG. Another term is VT, the threshold voltage that is the minimum gate voltage needed to induce a current. When VG and VDS applied are different, the behavior is different (Figure 143). Therefore, developing organic semiconductors with good charge mobility and stability is attracting researchers interest for obtaining organic field effect transistors with high performances.

Organic semiconductors OSC:

OSC can be oligomers or polymers knowing that there are two types of OSC, p-type and n-type. 328 P-type OFETs are of good performance on the other hand, n-OFETs are still behind.

In order to have n-type performance with suppressed p-type behavior, it is crucial to have a deep LUMO level to facilitate the electron injection and Low-lying HOMO level to prevent holes accumulation. This type of conjugated polymer can act as unipolar n-type performance; therefore, formation of n-channel. 329 One of the highest electron mobility in the literature is D-A conjugated polymer F4BDOPV-2T with an electron mobility of 14.9 cm 2 V -1 s -1 (Figure 144). Hence, synthesizing new n-type D-A conjugated polymers is crucial for n-type OFETs and organic thermoelectric materials.

To the best of our knowledge, 2,2'-Bithiophene-5,5'-dione (BTD) and benzo[1,2-b:4,5b']dithiophene-2,6-dione (BDTD) are two acceptor units of promising performance in D-A conjugated polymers. In the work of Kohsuke Kawabata and al three acceptor units have been used including BTD and BDTD (Figure 145).

Preliminary results:

A n-type conjugated polymer was previously synthesized with LUMO level at -4.52 eV, which is one of the lowest levels reported in the literature. This is a significant advantage to guarantee stable electronic properties at ambient conditions. However, lower average molar mass and a face-on π-stacking orientation of the chains are detrimental to reach high charge mobilities and certainly larger electrical conductivity after doping step. Hence, the aim of my PhD project is to enhance the solubility of the conjugated polymer for an increase in the average molar mass value to favor edge-on molecular orientation using functionalization with different alkyl side chains, and to improve the blend between the conjugated polymer and doping agent by introducing polar side chains such as triethylene glycol to the backbone of the conjugated polymer.

The objective was to prepare a narrow band gap electro-deficient conjugated polymer with a LUMO lower than -4.0 eV to guarantee stable charge transport properties at the ambient condition for ambipolar OFET and n-type OTE applications. The narrow band gap is interesting for ambient stable ambipolar OFETs development. 330 The increase of the planarity and the quinoid form stabilization favor higher electrical conductivity values of n-type materials after a doping process for n-type efficient OTE preparation. Inspired from the work of Pei and al, 283 who used benzo[1,2-b:4,5-b′]-difurran-2,6-dione as an acceptor. The idea was to use an acceptor with a stronger quinoid character as the sulfur-analog benzo[1,2-b:4,5-b′]dithiophene-2,6-dione (BDTD) developed by the Takimiya and al 59 and to replace the two thiophenes by EDOT unit to increase quinoid stabilization for increased polaron charge delocalization and enhanced electronic properties. In addition, the presence of EDOT increases the planarity with formation of non-covalent interactions S…O, which improve the π-stacking aggregation. In the synthesized conjugated polymer, the backbone is functionalized with branched alkyl chain to guarantee a good solubility to the polymer. The structure of the target polymer DG90 is depicted in figure 146. The planarity is increased by the insertion of EDOT moiety. The non-covalent intramolecular interaction S….O lock the conformation and improve the rigidity of the conjugated polymer. 331 Furthermore, they improve the molecular organization with a better π-stacking of the chains, which enhances charge transport. 332 Quinoid form stabilization is improved with the use of quinoid acceptor benzo[1,2-b:4,5-b′]-dithiophene-2,6-dione (BDTD), and it is reinforced with the presence of EDOT unit.

The project concerning the synthesis of n-type conjugated polymers for organic thermoelectric materials has been started in 2017 with the work of a post-doctoral Di Gao, who found the synthesis of an electro-deficient conjugated polymer, BDTD-2T-EDOT. It has one of the lowest LUMO in the literature (-4.52 eV) with a narrow band gap (Eg elec = 0.88 eV), hence, it is a promising candidate for n-OFET and OTEs.

The synthesis of the polymer DG90 (A) has been inspired of a reported procedure. 333,334,59 It is a multi-step synthesis depicted at scheme 20. The difference is the nature of the alkyl chain R carried by the thiophene ring and the final Stille coupling reaction, which allows the insertion of EDOT moiety. Compound B is an analogue of DG90. It was prepared to study the optical properties of an analogue of the monomer.

Scheme 20: The general synthetic route of the polymer DG90 including the two compounds A and B

After purification, the intermediates were characterized by 1 H, 13 C NMR and mass spectrometry (ESI). DG90 has been purified with a Soxhlet with hot chloroform, which yields to a first fraction DG90a, isolated after evaporation. The solid residue was re-extracted with a Soxhlet with hot chlorobenzene, a second fraction DG90b was obtained after solvent evaporation. The fractions were characterized by 1 H NMR. The average molar masses were determined by size exclusion chromatography (GPC) with polystyrene (PS) standards, the data shows that the first fraction DG90a is composed of polymer chains with shorter length, (Mn=14.6 Kg.mol -1 , Ɖ= 1.94, 11-12 units) in comparison to those from the second fraction DG90b (Mn = 23.8 Kg.mol -1 , Ɖ= 2.58, 23-24 units). MALDI-TOF analysis was carried out with DCTB (2-[(2E)-3-(4-tert-butylphenyl)-2-methylprop-2-enylidene]malononitrile) matrix by Julie Hardouin from PBS laboratory, Rouen. The mass spectrum of DG90b exhibited several ion series from m/z 3000 to 11000 with a mass gap of 859-860 Da between a series of molecular masses equal to the repeating units. It demonstrates the formation of an oligomer composed of 11-12 repeating units at least (Figure 147).

Figure 147: The MALDI-TOF spectrum of DG90b with DCTB matrix

The two obtained fractions showed different decomposition temperature with interesting behaviour with DG90a of Td of 341 °C that is higher than that of DG90b that is 329 °C (Table 15). The optical properties of the two fractions were investigated by absorption spectroscopy from 300 to 2400 nm with Julien Cardin in CIMAP laboratory, Caen. The data are summarized in table 15. In order to evaluate the capacity of absorption, the value of molar extension coefficients (ελ) for intermediate A and analogue B of the monomer (Scheme 20) were determined at 6.50 and 5.45 x 10 4 mol -1 L cm -1 , respectively. These values demonstrate a good absorption capacity. According to the absorption spectrum, both DG90 values absorb from 300 nm to 2400 nm. DG90a has an onset absorption at 1644 nm and maximum absorption at 1285 nm that corresponds to an optical band gap of 0.76 eV (Table 15). But DG90b shows onset absorption at 1999 nm with an absorbance maximum at 𝝀max of 1285 nm, which corresponds to a narrower band gap of 0.62 eV (Figure 148). The decrease in the band gap is in agree with the literature due to the increase in the conjugation length (Table 15). In the absorption spectra of the two fractions in thin film, DG90a shows maximum absorption at 1191 nm, while DG90b shows maximum absorption at 2126 nm. These values correspond to optical band gaps of 0.65 eV and 0.58 eV, respectively. The insertion of the EDOT allows smaller band gap in comparison to the value of band gap obtained for PBDTD4T that is of 0.88 eV. 59 Ambipolar behavior has been noticed, with hole and electron mobilities after calculating the hole to electron mobilities ratio, which is about 8 and 4.3 for DG90a and DG90b, respectively. For DG90b the obtained values (µe= 6.8 x 10 -3 cm 2 V -1 s -1 and µh= 1.6 x 10 -3 cm 2 V -1 s -1 ) are higher than those of DG90a (µe=1.2 x10 -3 cm 2 V -1 s -1 and µh= 1.5 x10 -3 cm 2 V -1 s -1 ), which could be due to the higher average molar mass in agreement with impact of molar mass on charges transport explained in chapter 1. After annealing treatment (molecular organization improvement under heating) the values of charge mobilities have been increased. However, these values are lower than those from the literature (PBDTD4T, µe= 0.35 cm 2 V -1 s -1 and µh= 0.30 cm 2 V -1 s -1 ). These values could be explained by the lower average molar mass and by the molecular organization of the chains, like face-on π-stacking orientation, which is detrimental to charge transport. So, we decided to carry out GIWAXD measurement to determine the orientation of the π-stacking in DG90b for further understanding.

GIWAX measurements were carried out in CRISMAT laboratory in Caen to study the πstacking orientation. The XRD pattern illustrated in figure 150 shows a "face-on" orientation of the π-stacking for DG90b. It is not favorable for good charge mobilities for OFET or OTE applications.

Figure 150: GIWAX XRD pattern of DG90b

Hence, both the face-on orientation and low average molar mass could explain the low electron mobility (μe= 6.8 10 -3 cm 2 V -1 s -1 ).

From these preliminary results, the objective of my PhD project is to enhance the electronic properties of the electro-deficient polymer. The strategy followed is to change the nature of the side chain R carried by thiophene rings from (BDTD-2T-EDOT)n inspired from reported examples by suitable types of chains, which will be chosen to increase the average molar mass, π-π aggregation, air/water stability and to trigger "edge-on" π-stacking orientation for the enhancement of the charge transport.

II.

New n-type Conjugated Polymers:

The objective is to synthesize a new narrow band gap and low lying LUMO n-type conjugated polymers with high electron mobility for n-type or ambipolar OFET applications and with high electrical conductivity for n-type OTE material preparation. From the preliminary results and a bibliographic study, a suitable chemical functionalization is applied on (BDTD-2T-EDOT)n with different side chains R carried on BDTD acceptor and R' on EDOT moiety (1) to increase the solubility and the average molar mass (Mn), (2) to enhance the π-π aggregation, (3) to trigger edge-on stacking orientation and (4) to have better air/moisture stability. The main target polymer is represented in figure 151.

Figure 151: The description of the main target polymer

Different targets have been imagined to study progressively the impact of each side chain on the solubility and the molecular organization. The generic synthesis is the same applied for the first polymer described in the preliminary results. The advantage of this synthetic route is testing one by one different side chains R and R' because they are carried on the distinct synthons B and C, respectively (Scheme 21). This helps to evaluate their impact on the solubility and molecular organization. The synthons A, B and C are attached sequentially after coupling reactions (Scheme 21).

Scheme 21: Generic synthesis of n-type conjugated polymer from the synthons A, B and C

with side chains R and R'

Based on the bibliographic study reported (paragraph 1.8 "side chain engineering" of this chapter), insertion of linear chains on conjugated polymers could improve aggregation with closest π-π spacing and more crystallinity. In contrast to branched chain, the solubility of the polymer could be lower, but this is favorable for increasing pre-aggregation chains mechanism and to trigger to preferential edge-on orientation. 336 This is demonstrated by the reported work of Fréchet and al with the preparation of n-C16H35 alkyl chain functionalized DPP-furane polymers. Compounds functionalized with linear chains exhibit better molecular organization and twice higher holes mobility values in comparison to the polymers with branched chains. 128 Hence, for the first target T1, linear chain n-C12H15 has been chosen to improve aggregation and to trigger edge-on π-stacking orientation. Besides, it would be easier to prepare rapidly the first BDTD derivatives (BDTD-1) and T1 (Figure 152), because 1bromododecane required in the synthesis is commercially available contrary to the extended branched alkyl chain, which is prepared in three steps (Scheme 15). 59 The solubilizing chain on the EDOT with target T2 could improve the solubility of the polymer and its average molar mass. If the solubility of BDTD-1 is not good enough for the syntheses, the extended branched alkyl chain could be used instead of linear ones in the preparation of BDTD-2 and the target T4 (Figure 152). These chains permit to maintain a good solubility of the polymer and improve molecular organization, which leads to the increase of the average molar mass and the enhancement of the charge transport. 337 Besides, the variation of the length (n: number of carbon atoms) of the spacer has an impact on the molecular organization, the size of the crystalline nanodomains and on the electronic properties. 338 The insertion of perfluoroalkyl chain (T3 and T6) on EDOT moiety permits higher degree of organization, inspired from reported work of Marc Sallé and al, with a gain of stability of n-type OFET as in the work of Kilwon Cho. 318 A final aspect is to improve molecular organization with the assistance of amphiphilic mesogenic groups, like triphenylene cores synthesized in the group with the 336 M. Li, C. An, T. Marszalek target T7. 339 Triphenylene groups self-assemble into columnar architectures. 340 The five alkyl chains per triphenylene group favor a good solubility of the polymer (Figure 152).

Figure 152: Explanations of the choice of targets T1-T7

The average molar mass will be determined by GPC. The microstructure of polymer thin films will be investigated by XRD to evaluate the crystallinity and the orientation of the πstacking. The charge mobilities will be measured on OFET device by Pr. Thomas Heiser from ICUBE laboratory in Strasbourg to evaluate the impact of the functionalization. In the final stage, the materials with the highest charge mobilities will be doped with different molar quantities of N-DMBI or TAM to achieve high electrical conductivity for OTE applications.

Synthesis of new n-type conjugated polymer T1:

The synthesis of the first target T1 is performed using multi-step reactions inspired from the literature 59,333,334 with optimization in the procedures. The synthesis is represented in scheme 22.

Scheme 22: The synthetic scheme for the synthesis of the conjugated polymer T1

The synthesis includes the formation of three synthons: the acceptor BDT 30 (synthon A), the stannic functionalized thiophene unit T-Sn (synthon B) and the distannic EDOT-Sn2 (synthon C).

Synthesis of the acceptor unit

The synthesis of synthon A (30) consists of four steps starting from 1,4dibromobenzene from a reported procedure. 59,333,334 The first step is iodination reaction using iodine as the source of iodine in sulfuric acid, which also played the role of solvent under controlled heating 125-135 °C to avoid further iodination that makes the separation of the desired product and by-product difficult. The large excess of acid causes many difficulties in the work up and the purification process. Hence, this step must be carried out with safety precaution. In addition, the precipitation of the product into hard-solid stones complicates the and restricts the purification step. Work-up optimizations have been carried to increase the yield. After the resynthesis of this compound, I supposed to carry out extraction of the liquid part, and to crash well the obtained stones with a maul into fine powder. The excess of iodine in the powder was removed after several triturations in pentane and a crystallization in chloroform. Since the presence of iodine traces with the compound prevents the formation of compound 28 after the Sonogashira coupling reaction. The yield was improved from 62 % in the reported procedures to 75 %. The second step is Sonogashira coupling reaction under inert atmosphere, which leads to diacetylenic compound 28 with triple bonds protected with trimethylsilyl (TMS) isolated with a yield of 68.5 %. It is prepared from bihalogenated derivative 27 and trimetylsilyacetylene (TMSA) in presence of protecting groups using (triphenylphosphine)palladium chloride as catalyst, CuI and diisopropylamine as base, which is dried and degazed with Argon. The yield of this step was significantly increased after improving the purification of the compound 27 for removing all traces of iodine.

The third step is a thiophilic reaction where bromine is replaced by methylsulfur group. The reaction of bishalogenated compound 28 and t-BuLi yields to the formation of the organolithium derivative, which reacts with dimethyldisulfide (DMDS) to form compound 29. The yield was increased from 50 % in the reported procedure 334 to 84 % by purifying the product with a precipitation instead of a column chromatography.

The acceptor 30 was obtained after an electrophilic cyclization reaction in the presence of iodine. The mechanism is represented in figure 153. The desired compound is isolated with a yield of 82 %.

The synthesis of the acceptor is composed of three stages: (1) the attachment of the synthon B, n-C12H25 functionalized thiophene ring to the Synthon A with a Stille coupling reaction, (2) the oxidation reaction to generate the thioesters functions after, which provides the electro-deficient nature to the acceptor BDTD 32 and (3) the bromination of the acceptor 32. The oxidation step is the limiting step in this synthesis, since the synthetic route was inspired by the work of Takimiya and al (Scheme 23) with the preparation of the same acceptor nature with branched alkyl chain with a yield of 47 %, 59 but in our synthesis, we use linear alkyl chain. This procedure was applied for the synthesis of the same acceptor functionalized by branched alkyl chains with a lower yield of 27 % for the preparation of DG90 (See part of preliminary results in this chapter).

Scheme 23: The synthetic route followed for the synthesis of intermediate 33 (BDTD-T2)

The synthesis of intermediate 31 requires the synthesis of the donor unit that is a stannic thiophene molecule substituted with linear alkyl side chain.

The functionalized thiophene TSn1 is synthesized by two steps, which are inspired by the literature (Scheme 24). 254 The first step is a Kumada cross-coupling reaction, which involves preparing a Grignard reagent from bromododecane. The linear chain functionalized thiophene TR1 is isolated after purifications using silica column chromatography and vacuum distillation with a yield of 74 %. The second step is the organotin formation from the reaction between anion formed by lithiation at -78 °C of TR1 and tributyltin chloride. TSn1 is isolated after an extraction with no further purification with a yield of 91 % (Scheme 24).

Scheme 24: The synthesis of TSn1 (Synthon B)

After preparing synthon A and synthon B, the next step is a Stille coupling reaction between the bisiodine acceptor 30 (Synthon A) and the organotin thiophene derivative TSn1 (Synthon B) in the presence of tetra triphenylphosphine palladium catalyst under a reflux of three days. Then, 1M TBAF solution is added to remove TMS groups (Scheme 25).

Scheme 25: The synthesis of intermediate 31

The overall yield of these two successive steps is 71 % yield after optimization on the reaction conditions and purification step summarized in table 17. At the beginning, the procedure was applied according to the literature. The obtained product was isolated with low yield (25 %). After a progressive increase in the number of equivalents of Pd(PPh3)4 from 0.01 to 0.1 allows an increase in the yield from 25 % to 48 %. However, the addition of TSn1 in portions during 24 hours results in higher yield of 71 %. The next reaction is the oxidation reaction of the intermediate 31 to generate the acceptor BDTD with the formation of withdrawing thioester functions, illustrated in scheme 26. This is the limiting step of the synthetic route. The reaction procedure was inspired by the work in the literature 59 of the same acceptor with different side chain.

Scheme 26: The synthesis of intermediate 32

The synthesis of intermediate 32 consists of deprotonation of the compound 31 with the strong base lithium tetramethylpiperidine freshly prepared from n-Buli (2.5 M) and 2,2,6,6-tetramethylpipyridine. The anionic intermediate reacts with triisopropylborate to give the boronic ester derivative. It is followed by hydrolysis of the boronic ester to boronic acid with 1M HCl solution. Then oxidation takes place at the boronic acid position with hydrogen peroxide at room temperature (Scheme 26). This limiting step requires strict anhydrous and inert conditions. Several attempts were carried out to improve the reactivity of the reaction and the yield.

First, the reaction conditions used for DG90 synthesis have been tested, inspired from the literature (Entry 1, Table 18), but the desired product was not isolated even if the reaction time was increased (Entry 2). However, the reaction took place when the base 2,2,6,6-tmpp is being freshly dried over calcium hydride and freshly distilled under vacuum (Entry 3). For better understanding, the reaction was monitored by 1 H NMR to evidence the formation of the boronic and the desired compound 31.

The formation of the desired compound 32 is confirmed by 1 H NMR and by mass spectrometry with the determination of the exact mass. The low solubility of the intermediates could explain the lack of reactivity and reproducibility but also the low stability of the compounds. Hence, Different solvents have been tried in order to increase the solubility of the intermediate during the deprotonation step. However, all the tested solvents result in poor solubility, keeping in mind we must control the molar concentration of the base (2.5 M) The conditions are listed in table 18. After confirming the presence of intermediate BDTD-1 32, it was engaged in bromination reaction with NBS to obtain the final intermediate 33. It was not stable enough in solutions nor in deuterated solvents to be well characterized in 1 H and 13 C NMR. But the 1 H NMR spectrum analysis revealed the absence of the proton signal at 7.25 ppm, which corresponds to the proton at the alpha position of the thiophene ring, which agrees with the presence of bromine. Besides, the compound was characterized by mass spectrometry with the detection of the molecular peak with the presence of 2 bromines and a peak from ionic fragment in the presence of one bromine. The exact mass confirmed the formation of the product 33. Hence, this product was directly engaged in the final step to form the conjugated polymer T1. In perspective, to increase the solubility and the stability. It was planned to synthesize the analogous intermediate BDTD-2 (Figure 152) with extended branched chains, introduced in the chapter 2. This intermediate will be used for the preparation of the target T4.

Synthesis of EDOT-containing units (Synthon C):

This part is dedicated to the description of the synthesis of the three EDOT containing synthons C represented in figure 154. Synthon C1 was synthesized since it is the same intermediate engaged for the preparation of DG90 polymer. This will help us to compare T1 and DG90. Hence, we can study the impact of the linear chain on the molecular organization and the electronic properties. For synthon C2, it is like synthon C1 but with additional linear chain C12H25 that is inserted on the cycle of EDOT to increase the solubility of the polymer and maintain a good aggregation. For Synthon C3, a perfluoroalkyl chain was added to increase the aggregation and the electron mobility with the improvement of the stability of the material inspired from reported example (Figure 154).341 Synthon C1 (34) is required for the synthesis of T1. The synthesis of 34 starts with a lithiation of EDOT with n-BuLi at -76 °C followed by a reaction with tributyltin chloride as reported procedure. 342 The bis-stannic derivative was isolated after an extraction and engaged in the preparation of T1 without further purification (Scheme 27) with complete conversion according to 1 H NMR spectrum.

Scheme 27: The synthesis of di stannic EDOT (Synthon C1) 34 1.3.2. Synthesis of Functionalized EDOT Synthon C2 (41) The Synthon C1 (36) is required for the preparation of the target T3. This compound was prepared with Cyprien Lemouchi in three steps from dibromothiophene. The first step is the formation of dimethoxythiophene from reported procedures. The second step is the preparation of C12H25-EDOT (35). First the compound was not isolated by following the reported procedures. 343 Sequential additions of p-TSA with excess permit to obtain the target compound with a yield of 75 %. Bis-stannic derivative (Synthon C2, 36) can be prepared from the same procedures described for EDOT moiety (Scheme 28). Concerning the synthesis of Synthon C3, the strategy is the functionalization of the EDOT with perfluoroalkyl side chain. These chains have attracted our attention due to their hydrophobic character which plays a role in increasing the thermal and chemical stability of the polymer. Another interesting character is their ability to self-organize. The synthesis of Synthons C3 was carried during Master 2 internship period of Victor Boshevski. That was an opportunity for me to train a Master 2 trainer on this research project with the participation of Cyprien Lemouchi and Loïc Le Pluart.

The synthesis of perfluoroalkyl chain functionalized EDOT has been reported, by the group of Mark Sallé. 320 The compound was prepared in two steps from EDOT-CH2OH (Figure 155a). the target compound (Figure 155a). In our group, we were interested to test more convergent synthesis with the direct functionalization of the enantipore EDOT-CH2-X with different types of chains for the insertion of solubilizing chain or amphiphilic organizing groups as described in figure 155b.

Direct Functionalization of (R)-EDOT-MeOH and (R)-EDOT-MeCl with perfluoroalkychain

For the synthesis of Synthon C3, we worked on the direct functionalization of the starting material EDOT-CH2-OH 13 prepared in four steps or EDOT-CH2-Cl 11, which is prepared in two steps from dibromothiophene, (Chapter 2, Scheme 12). Besides, the reactions have been carried out from the enantiopure (R) compounds 13 or 11, which are described in chapter 2 to prepare stereoregular conjugated polymer with enhanced molecular organization and increased charge transport. 344 For the synthesis of the functionalized EDOT there are two routes exist in the literature for Williamson reaction described in figure 156. Following route 1, the EDOT functionalized with perfluorinated chain is prepared from the reaction between a halogenated perfluoroalkyl chain and an alcoolate obtained from EDOT-CH2-OH 13 after deprotonation in the presence of a base. However, in route 2, the reaction is between the halogenated EDOT (EDOT-CH2-Cl) 11 and perfluoroalcoolate, which is obtained after the deprotonation of perfluoroalkyl chain.

To begin with, route 1 was explored with the preparation of the perfluorinated EDOT 37 as described in scheme 29 and inspired by the work of S. Geribaldi and al. 345 Scheme 29: Route 1 for the synthesis of intermediate 37 According to S. Geribaldi and al in such type of reactions, β-elimination side reaction is a risk on the iodinated perfluorinated chain. Therefore, we have decided to start from their condition to prevent the elimination. 345 So, the reaction was carried at room temperature in THF but with 2.5 eq. of NaH (Entry 1, Table 19). However, the target product was not isolated even with the increase of the number of equivalents of NaH to 4, 10 and 20 (entries 2-4, Table 19). Then, the reaction was heated to 67 °C, but as expected the heating promoted the elimination reaction with formation of the compound 37' (Entry 5, Table 19). Finally, the use of DMF as solvent instead of THF with a large excess of NaH (10 eq.) permits us to isolate the compound 37 with a yield of 40 % with traces of the elimination product 37' (5 %) (Entry 6, Table 19)) according to 1 H NMR analysis. The Williamson reaction was favored by the better solubility of perfluorinated chain in DMF. Nevertheless, the separation of the desired compound from the byproduct 37' is tedious. For route 2, the best reaction condition of route 1 (Entry 6, Table 19) was first applied. This route starts by deprotonation of the alcohol terminal of perfluorinated chain followed by the reaction with EDOT-CH2-Cl 14 (Scheme 30). The formation of the alcoholate leads to more polar product and then better solubility in DMF. The yield of the reaction increases significantly with a vigorous stirring. Compound 38 was obtained as yellowish oil with a yield of 65 %.

Synthesis of (R)-EDOT-R-OC10F21 with spacer: a) Insertion of the spacer on the EDOT moiety:

Scheme 32: The synthesis of intermediate 39 Following the same strategy of Williamson reaction (Entry 6, Table 19) of route 1, compound 23 was deprotonated using NaH in DMF, followed by nucleophilic substitution reaction of the alcoolate on the iodinated perfluorinated chain to obtain compound 39 in a yield of 71 %. Formation of the target compound was confirmed by 1 H NMR and mass spectrometry. We have decided also to test the opposite strategy to insert the spacer on the perfluoroalkyl chain and to make it react on EDOT-CH2-Cl.

b) Insertion of the spacer on the perfluoroalkyl chain:

The spacer has been linked to the perfluorinated chain, and the deprotonated alcohol reacts on EDOT-CH2-Cl (Scheme 33). The chain with spacer 41 was prepared in two steps. The first step is the reaction between perfluorinated alcoholate and the bromoalkyl chain 17 with alcohol function protected with TBDMS to form compound 40 with a yield of 83 %. Then, the deprotection of the TBDMS groups is carried out with TBAF. The yield of the obtained compound 41 is 62 % (Scheme 33).

Scheme 33: The synthesis of compound 41

Besides, we have tested the reaction conditions of route 2 to compare the yields. But the reaction of perfluoroalcoolate on on (R)-EDOT-CH2Cl didn't work (Scheme 34). Preparation of the polymer T1 is difficult due to the low yield obtained from the oxidation reaction. Only limited quantities of the intermediate 33 were prepared. The lack of reactivity, stability of the final intermediates and the reproducibility of the oxidation step could be explained by a lower solubility of the samples. In perspective, this could be overcome by changing the linear chain by extended branched chains in order to improve the solubility and to check the improvement of the reactivity with the preparation of T4 (Cf. Objectives part, Figure 152).

III. Conclusion and Perspectives

During the work of this chapter, most of Synthons C have been synthesized, except synthon C3, which is the EDOT functionalized with perfluorinated chain. It requires the addition of the stannic function. Concerning Synthon B, it is successively synthesized to be integrated in the synthesis of BDTD intermediate after Stille coupling reaction.

However, the synthesis of BDTD acceptor is quite difficult due to the limitation in the oxidation step. This limitation mainly was because of the poor solubility of the intermediate used as an impact of the presence of the linear alkyl chain as well as not enough stability of intermediates and products obtained during the three successive steps for obtaining the ketone function. After several attempts we were able to obtain the desired molecule with low yield.

Therefore, only one of the designed targets T1 has been synthesized, which is the reference conjugated polymer to compare with the previously synthesized polymer in the team DG90. After applying two polymerization conditions using microwave and different solvents, we were able to obtain two samples of T1, MQ187 and MQ192. MQ187 has the advantages of obtaining a higher proportion of long chain polymers than short chain polymers. However, MQ192 has the advantage to have the highest molecular weight polymer of 330 Kg.mol -1 , which is a promising result.

The next approach is to functionalize our polymer with extended branched chain instead of linear chain to alternate acceptor group BDTD with higher solubility and probably better reactivity. This will allow us to study the impact of the organizing groups (Synthons C) that is the functionalized EDOT. Therefore, this allows the synthesis of target T4 as exemplified in figure 158. The solubility and stability will be tuned using various functionalized EDOT groups, which are already prepared leading to a new family of targets T4-T6. In the same manner of T1 preparation, the key intermediate AA of polymer T4 synthesis would be prepared from synthon B' (Figure 159). The synthesis of synthon B' requires the preparation of extended branched chain 22a or 22b with change in the length of spacer according to synthetic strategies reported in the literature and described in chapter 2 of this manuscript.

General Conclusion:

Fabricating organic electronics such as organic solar cells, and organic field effect transistors requires the synthesis of organic semiconductors. These materials are mainly conjugated polymers and they are of two types: p-type and n-type. Both types are required to be designed and studied by researchers for obtaining organic electronic and photovoltaic devices with high performances. In this manuscript, two types of materials have been synthesized: Diketopyrrolopyrrole DPP based metallooligomers as donor materials for bulk heterojunction solar cells (BHJSCs) as well as electro-deficient conjugated polymers (n-type) for n-type organic field effect transistors or for thermoelectric materials after doping.

New metallooligomers with enhanced performances for solar cell applications were synthesized from a dehydrohalogenation reaction from a ligand Lx with trans-PtCl2(PBu3)2 in the presence of CuI and a base (Scheme 36). The metallooligomers are composed of DPP containing organic part (Ar) with a lactam function functionalized with a linear alkyl chain for better π-aggregation. The triple bonds from Ar are connected to Pt-transition metal (Scheme 36). The presence of transition metal offers additional benefits in respect with analog conjugated polymers. It helps tuning the electronic structure of the polymer and induce specific properties such as: long term stability, upper triplet state formation, enhanced light absorption and high carrier mobility. 216 In this work, two strategies have been developed for the enhancement of the optical and optoelectronic properties of the metallooligomers. The objectives were decreasing the optical band gap in order to reduce energy losses with broadened absorption wavelength range and improving the molecular organization in order to increase charge mobilities.

Scheme 36: The general synthesis of metallooligomers using dehydrohalogenation reaction

The methodology of the first strategy was increasing the conjugation length by inserting two thiophene rings to the Ar part with respect to an already synthesized P1' with the preparation of PA (Figure 160). The goal was increasing the average molar mass of PA by improving the reaction conditions of the dehydrohalogenation step and by increasing the solubility of the metallooligomer through functionalization the ligand with a solubilizing alkyl chain. The optimization of the dehydrohalogenation step permits to double the Mn value. Yet, the obtained metallooligomer PA shows instability issues under illumination and irradiation, which prevents its use as a donor in BHJSCs. These results have been published in 2022 in JIOP. Hence, the metallooligomer PB was prepared with a solubilizing linear alkyl chain added on the second thiophene to increase the solubility and to maintain a good π-π aggregation. Nevertheless, the metallooligomer PB was not isolated because of lower reactivity of the ligand LB in the dehydrohalogenation step (Figure 161). Therefore, a second strategy has been applied to synthesize new metallooligomers with better properties. The second strategy is based on the use of DPP dimers in the organic part (Ar) to decrease significantly the optical band gap. Hence, a narrow band gap metalloligomer P2' (Eg =1.42 eV) has been previously prepared in the team (Figure 162). The performances of BHJSCs showed PCE about 9.42 % with P2' as a donor and PC71BM as an acceptor. Our goal was to prepare a new low band gap metallooligomer, which can be prepared in larger scale with similar or better optical and optical properties. This requires a simplified synthetic route and increased stability of the deprotected ligand to improve the dehydrohalogenation step with formation of metallooligomers with higher chain lengths. In the first approach, the second thiophene was replaced by 3,4-ethylenedioxythiophene (EDOT), which is a stronger donor unit with increased push-pull effect with DPP moiety. Moreover, EDOT unit can increase the planarity of the conjugated backbone by S…O interactions, it increases the stabilization of quinoid structure, and it could be easily functionalized. The metallooligomer PC showed a twice higher average molar mass of 12.4 Kg.mol -1 in respect of P2'. PC shows an optical band gap value of 1.48 eV close to P2' in agreement with Eg elec of 1.42 eV with of 𝝀abs (onset) of 840 nm and 875 nm for PC and P2', respectively. Besides, LC discloses a higher molar extinction coefficient (ε𝝀) (4.81x 10 4 mol -1 L cm -1 , 5.17 x 10 4 mol -1 L cm -1 ) in comparison to L2' (1.39 x10 4 mol -1 L cm -1 , 1.42 x10 4 mol -1 L cm -1 ). From these promising results, the resynthesis of PC in larger quantities (to multiply by 10 the quantities) was performed, which required the optimization of some steps to improve the yields, like the dehydrohalogenation step to increase the purity and the average molar mass of PC. Using PC as a donor in a BHJSC led to PCE of 8.96 % with PC71BM, 11.94 % with IT-4F and a record of performances for [Pt]-metallooligomers with a PCE of 14.12 %, when associated to the acceptor Y6. As a perspective, PC could be resynthesized to be used in ternary systems (donor/ acceptor1/ acceptor2) to increase these performances.

The synthesis of PC also opened the opportunity for the preparation of metallooligomers with functionalized EDOT. The optoelectronic properties could be enhanced with the insertion of a side chain on the EDOT moiety. The presence of alkyl chains helps to increase the solubility, polar group can increase the exciton dissociation or siloxane group that can increase the donor/acceptor segregation, and the chain could be an organizing group as triphenylene. This family of metallooligomers requires the synthesis of two synthons (R/S)-EDOT-MeOH and (R)-EDOT-MeOH. The chiral EDOT ((R)-EDOT-MeOH) has been chosen to be functionalized due to the additional chiroptical properties. Different functionalized EDOT have been synthesized and characterized. Monostannic functionalized EDOT (25) has been prepared and integrated in Stille coupling reaction for the synthesis of intermediate 26, which is a key step in obtaining a new ligand LD and consequently the metallooligomer PD (Scheme 37).

Scheme 37: The general synthetic route of PD using functionalized EDOT Regarding n-type conjugated polymers, a previously prepared polymer (DG90) composed of benzo[1,2-b:4,5-b′]-difurran-2,6-dione as an acceptor flanked with thiophene units as a donor unit functionalized with branched alkyl chain inspired from the work of Pie and al 283 displayed a low lying LUMO level of -4.52 eV. EDOT unit has been inserted to increase the planarity, to improve the rigidity of the conjugated polymer backbone by S…O interactions and to increase the quinoid stabilization. However, this polymer displayed rather low charge mobilities (µe= 6.8 x10 -3 cm 2 V -1 s -1 and µh=1.6 x10 -3 cm 2 V -1 s -1 ), which could be explained by an unfavorable orientation of the chains stacking and a low average molar mass of 23.8 Kg.mol -1 . We aimed to improve the electronic properties of this polymer. According to the literature, electronic properties of n-type conjugated polymer can be enhanced by improving its stability at ambient condition by lowering the LUMO level (ELUMO < 4.00 eV) or by functionalizing the polymer with perfluoroalkyl chains. The increase of the average molar mass helps to improve charges transport as well as to favor better conductivity. Consequently, our goal was to change the side chain carried on thiophene to trigger edge-on orientation and better aggregation, then to insert a solubilizing chain on the EDOT to improve the solubility of the polymer to increase the average molar mass (Figure 163).

The targets were prepared from a convergent synthesis with the use of synthons A, B and C. This strategy permits to change rapidly the type of side chain (R and R') when a lack of solubility or a wrong π-π-stacking orientation is detected. The steps of this synthesis have been optimized to improve the global yield. A first polymer T1 with linear chain (R) was synthesized to increase molecular organization. But T1 was not pure enough and displayed a large molar mass dispersity, which prevented it from being analyzed. This could be explained by the lack of the solubility of the final intermediates which prevents obtaining larger quantities.

As a perspective to this work, extended branched chains could be used in the preparation of T4 to increase the solubility of the final intermediates. The use of distinct synthons C functionalized with perfluoroalkyl chains and organizing groups to improve the stability and the molecular organization for the development of efficient and stable n-type OFET and n-type OTE at ambient conditions can also be reasonably targeted.

Materials and Methods

The Density functional theory (DFT) calculations were then performed to validate the targets Ln and Pn. by using the Gaussian09 348 at the Université de Sherbrooke with the Mammouth supercomputer supported by Le Réseau Québécois De Calculs Hautes Performances. The DFT geometry optimizations and Time dependent DFT (TD-DFT) calculations 349 were carried out using the B3LYP method. A 6-31g* basis set was used for C, H, N atoms. 350 It is important to note that DFT calculations for all the molecules were made using a dichloromethane solvent field.

All the chemicals were purchased from commercial suppliers (Fischer Scientific, Sigma-Aldrich, Strem Chemicals, VWR chemicals) were used as received. The solvents (THF, CH2Cl2, CHCl3, trimethylamine,…) were dried and distillated before use.

Thin layer chromatography (TLC) was performed on Merck Silica gel 60 T254 (coated on aluminium sheet). Column chromatography was performed using silica gel 40-63 μm NMR 1 H, 13 C and 31 P spectra were recorded on BRUKER Avance III400 and BRUKER Avance III500 in CDCl3 and CH2Cl2 using TMS as an internal standard. Chemical shifts are External calibrations were carried out using the standard protein mixture (Peptide Calibration Standard kit, Bruker Daltonique). At least 150 laser shots were summed for each spectrum.

Raw data were processed using Flex Analysis. purple. After cooling to room temperature, the mixture was poured onto dilute HCl (1N, 100 mL) and was stirred vigorously for 1h at 0°C, the precipitated deep purple solid was collected by filtration under vacuum. Then the solid was washed several times with methanol and dried under vacuum to give a purple powder (5.7 g, 19.00 mmol, 54 % yield) and used without further purification. (1.4 g, 4.67 mmol), anhydrous potassium carbonate (2.6 g, 18.81 mmol) and 18-crown-6 (cat., 5 mg) were added in freshly diStilled DMF (70 mL). The mixture was stirred at 100 °C for 1 h under argon atmosphere. Then, 1bromononane (2.9 g, 14.00 mmol) was added dropwise and the reaction mixture was stirred at 100 °C for 36 h, monitored in TLC (Rf = 0.6, using CHCl3 as eluent). When the reaction was complete, the reaction mixture was cooled to room temperature and extracted with CH2Cl2 (200 mL). The isolated organic layer was washed with brine (4 x 100 mL), dried over MgSO4, filtered and evaporated under reduced pressure. The crude material was purified by chromatography using silica gel with CHCl3 as eluent to afford 2 as a purple solid (1.8 g, 3.26 mmol, 70 % yield). -1 ): v = 3069 (v, C-H aromatic), 2918 and 2848 (w, v (N-CH2)), 2145, 1655 (w, v(C=O)). 20 mol%) were added. Then 2-(tributylstannyl)thiophene (commercially available) (227.6 mg, 0.61 mmol, 2.5 eq.) was added. The mixture was refluxed overnight under argon atmosphere.

IR (cm

After cooling, the solvent was evaporated under reduced pressure. The resulting solid was retaken in a mixture CH2Cl2/CH3OH: 30 mL/ 30mL, then filtered and washed with methanol several times to get compound 4 as dark-purple solid (104.8 mg, 0.15 mmol, 60 % yield). (185.0 mg, 0.258 mmol) was dissolved in chloroform (20 mL). The solution was cooled to -5 °C with ice bath with NaCl. Keeping the temperature below 0°C, bromine (87 mg, 0.542 mmol) was added. Then, the mixture was stirred at a temperature below 0 °C for 3 hours. Be cautious: higher temperature causes degradation of the product with by-reactions and provides lower yields. The reaction was monitored by TLC (disappearance of the starting material Rf=0.6 and formation of brominated compound, Rf=0.7, using pentane/CH2Cl2:1/1 as eluent). The reaction mixture was quenched with sodium thiosulfate aqueous solution and extracted with methylene chloride. The organic layer was washed twice with water and evaporated under reduced pressure. The liquid residue was retaken several times with toluene and evaporated to remove water traces. The crude product (m= 200 mg) was obtained as a dark purple solid, which is a mixture of 5 and 5' evidenced by MALDI-TOF. Since the separation of those products was very difficult, the crude material was directly engaged in the next step. Be cautious: the brominated compounds are not very stable, they must be stored in the fridge and protected from light exposure, they must be rapidly engaged in the next step. The procedure was inspired from the literature, R.Y. cooled to 0°C and bromine (32 mg, 0.199 mmol) was added slowly. The mixture was stirred was stirred at 0°C and the reaction was monitor by TLC (eluent: CH2Cl2/pentane: 1/1, Rf (7) =0.8). The reaction mixture was quenched with sodium thiosulfate aqueous solution and extracted with CH2Cl2. The organic layer was washed with water and brine, then it was dried over MgSO4, filtered and evaporated under reduced pressure. The crude product was isolated as a dark blue solid, 120 mg. 1 H NMR spectrum has a poor resolution, and it was directly engaged in next step. The mixture was refluxed at 70 °C overnight and monitored by TLC (eluent: CH2Cl2/pentane: 50/50, Rf (LB) = 0.5). The solution was evaporated under reduced pressure and the crude product was purified by column chromatography on silica gel using pentane/CH2Cl2: 50/50 as eluent to provide LB as a dark blue solid (65 mg, 0.052 mmol, 66 % yield from 6). and extracted with CH2Cl2 (2 x 15 mL). The organic phase was afterwards washed with distillated water (10 mL) and the solvent was removed under reduced pressure. The crude product was isolated by flash chromatography (puriFlash XS 520 Plus, 100 % pentane to 9/1 pentane/EtOAc), to afford the product 18 (0.32 g) as a colorless oil in 71 % yield.

IR (cm

11-(bromomethyl)tricosane (19)

To a solution of triphenylphosphine (5.72 g, 20 mmol) in dichloromethane (15 mL) was added 2-decyl-1-tetradecanol SM (5.0 g, 14.1 mmol). Then, N-Bromosuccinimide (3.76 g, 20 mmol) was added to the mixture at 0 °Cover 20 minutes. After the reaction mixture was stirred at room temperature for 20 h. The reaction mixture was quenched with distillated water (20 mL) and extracted with CH2Cl2 (3 x 20 mL).

The organic phase was dried over MgSO4 and the solvent was removed by evaporation to furnish the crude product. Purification by column chromatography (silica gel, 100 % pentane to 8/2 pentane/ CH2Cl2) gave pure brominated product as a colorless oil (5.288 g) in 90 % yield.

1 H NMR (500 MHz, CDCl3) δ (ppm): 3,45 (d, 3 JH-H = 5Hz, 2H), 1.58 (m, 1H), 1.26 (s, 40H), 0.88 (t, 3 JH-H = 7Hz, 6H). The mixture was then warmed to room temperature and stirred for 2 h. The Grignard reagent was then transferred to a three necked flask and diluated with THF (7.76 mL). To the solution was added dropwise a solution of ethylne oxide (1.2 M in THF) (0.4 g, 9.0 mmol) at 0 °C over 5 min. After the reaction mixture was stirred at 50 °C for 6 hours. The reaction was quenched with 1 M hydrochloric acid. The reaction mixture was extracted with pentane, and the organic layer was washed with water and dried over MgSO4. After removing the solvent by evaporation, the crude product was purified by column chromatography (silica gel, 100 % pentane to 75/35 pentane/EtOAc) to give the product 21 (0.5 g) in 30 % yield.

1 H NMR (500 MHz, CDCl3) δ (ppm): 3.61 (t, 3 JH-H = 6.7 Hz, 2H), 1.53 (quintet, 3 JH-H = 7.1 Hz, 2H), 1.35 -1.14 (m, 43H), 0.87 (t, 3 JH-H = 6.7 Hz, 6H). 59 To a solution of triphenylphosphine (0.21 g, 0.78 mmol) in dichloromethane (1.4 mL) was added bromine (0.13 g, 0.78 mmol) at 0 °C over 10 min. After the reaction mixture was stirred at 0 °C for 20 min, 21 (0.25 g, 0.65 mmol) was added dropwise over 5 min at 0 °C. After the reaction mixture was stirred at room temperature for 20 h. The reaction was quenched with distillated water (5 mL) and extracted with DCM (2 x10 mL). The organic phase was dried over MgSO4, filtered and the solvent was evaporated under reduced pressure. The crude product was purified by silica gel column chromatography (eluent: 100 % pentane) to give 22 (0.18 g) as colorless liquid in 62 % yield.

1 H NMR (500 MHz, CDCl3) δ (ppm): 3.42 (t, 3 JH-H = 7.2 Hz, 2H), 1.81 (quintet, 3 JH-H = 7.4 Hz, 2H), 1.37 -1.24 (m, 43H), 0.89 (t, 3 JH-H = 6.8 Hz, 6H).

6-((5-(tributylstannyl)-2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy)hexan-1-ol (23)

To a 25 mL two-necked flask equipped with Ar purge, the product 6 (0.12 g, 0.31 mmol) and dry THF (1.3 mL) were added. Then, 0.5 mL of TBAF (1M)

were added to the mixture. The reaction took place at RT for 16 h. The reaction mixture was poured into water (10 mL) and extracted with ethyl acetate (2 x 15 mL). The combined organic extracts were washed with a saturated aqueous chloride solution (2 x 15 mL), brine (2 x 15 mL), dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to furnish the crude product as a yellowish oil. Purification by flash column chromatography (silica gel, 100 % penatne to 1/1 pentane/EtOAc) furnished pure alcohol as a yellowish oil (0.065 g) in 81 % yield.

(R)-2-(((6-((4-decylhexadecyl)oxy)hexyl)oxy)methyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine (24)

To a 10 mL two-necked flask equipped with Argon purge, the product 23 (0.065 g, 0.24 mmol), NaH (60 %) (0.1 g, 2.4 mmol), 18crown-6 (0.03 g, 0.16 mmol) and dry DMF (2 mL) were added. The mixture was stirred at RT for 1 h. Then, 22 (0.11 g, 0.29 mmol) was added dropwise into the mixture. After 18 h of reaction, the mixture was poured into a saturated solution of NH4Cl (10 mL) and extracted with CH2Cl2 (2 x 10 mL). The organic phase was afterwards washed with distillated water (8 mL) and the solvent was removed under reduced pressure. The crude product was isolated by flash chromatography (puriFlash XS 520 Plus, 100 % pentane to 9/1 pentane/DCM), to afford the product 24 (0.095 g) as a colorless oil in 63 % yield.

1 H NMR (500 MHz, CDCl3) δ (ppm): 6.36 (d, 4 JH-H = 3.7 Hz, 1H), 6.34 (d, 4 JH-H = 3.7 Hz, 1H), 4.28 (m, 1H), 4.27 (dd, 2 JH-H = 11.6 Hz, 3 JH-H = 7.6 Hz, 1H), 4.04 (dd, 2 JH-H = 10.4 Hz, 3 JH-H = 6.2 Hz, 1H), 4.27 (dd, 2 JH-H = 11.7 Hz, 3 JH-H = 7.6 Hz, 1H), 3.64 (t, 3 JH-^H = 7.4 Hz, 2H), 3.58 (dd, 2 JH-H = 10.4 Hz, 3 JH-H = 6.3 Hz, 1H), 3.39 (t, 3 JH-H = 6.8 Hz, 4H), 1.62-1.49 (m, 10H), 1.37-1.13 (m, 43H), 0.86 (t, 3 JH-H = 6.7 Hz, 6H). To a small tube purged with argon, the compound 6 (0.2 g, 0.52 mmol) and dry THF (0.06 mL) were added. The mixture was cooled down to -75 °C and n-BuLi [2.5] (0.04 mL, 0.46 mmol) was slowly added dropwise to the mixture. After one hour of deprotonation, the Cl-Bu3Sn (0.13 mL, 0.46 mmol) was added dropwise at -75 °C.

The reaction mixture was then let cool down to rt and stirred for 18 h. The reaction mixture was quenched with distillated water and extracted with CH2Cl2 (3 x 15 mL). The organic fraction was dried and filtered and the solvent was removed to give the pale brown colored product. This compound was used without further purification. To a 10 mL tube, purged with Ar, the compound 25 (0.145 g, 0.066 mmol) and dry toluene (5 mL) were added. Then, the acceptor DPP (0.014 g, 0.02 mmol)

was added to the solution. After bubbling the solvent under Ar, 10 mol% of the PdCl2(PPh3)2 and 20 mol% of the PPh3 were added to the reaction mixture. The reaction was stirred over night for about 18 h. The mixture was quenched with distillated water and extracted with DCM (3 x10 mL). The organic phase was dried over MgSO4, filtered and the solvent was evaporated under reduced pressure to furnish the crude product.

Purification by Biobead® X1 by Size Exclusion Chromatography by 100% CH2Cl2 . Then, a purification by column chromatography (siliga gel, DCM/Toluene 9/1) was done. Alternatively, removed under reduced pressure. The crude product was isolated by flash chromatography (puriFlash XS 520 Plus, 100 % pentane to 6/4 pentante/EtOAc), to afford the product 39 (0.16 g) as a yellowish oil in 71 %. To a 25 mL two-necked flask equipped with Argon purge, the perflurinated chain (0.55 g, 0.99 mmol), NaH (60 %) (0.4 g, 9.9 mmol), 18-crown-6 (0.03 g, 0.16 mmol) and dry DMF (16.5 mL)

were added. The mixture was stirred at RT for 1 h. Then, the product 17 (0.35 g, 1. 18 mmol) was added dropwise into the mixture. After 18 h of reaction, the mixture was poured into a saturated solution of NH4Cl (20 mL) and extracted with CH2Cl2 (2 x 20 mL). The organic phase was afterwards washed with distillated water (8 mL) and the solvent was removed under reduced pressure. The crude product was isolated by flash chromatography (silica gel, 100 % pentane to 6/4 pentane/ EtOAc), to afford the product 40 (0.57 g) as a colorless oil in 83 % yield.

Résumé

Ce manuscrit se compose de deux parties. La première partie se concentre sur le développement de nouveaux métallooligomères à faible gap électronique utilisés comme donneurs dans les cellules solaires organiques à hétérojonction. Ils sont préparés par une réaction de déhydrohalogénation entre un ligand L et le trans-PtCl2(PBu3)2. Ils sont constitués du métal platine avec les ligands phosphines et d'une partie organique composée de donneur (thiophènes) et d'accepteur avec le dicétopyrrolopyrrole (DPP). Pour réduire le gap électronique, la stratégie utilisée consiste à modifier la structure du ligand pour augmenter de la longueur de conjugaison, la planéité, la stabilisation de la forme quinonique ou renforcer l'effet « push-pull » en particulier avec l'insertion du 3,4-éthylènedioxythiophène (EDOT). Cette stratégie a permis de préparer de nouveaux donneurs qui ont permis d'atteindre de bonnes performances avec des PCE de 14-15 % lorsqu'ils sont associés avec des accepteurs non-fullerènes. Dans la deuxième partie, l'objectif est de synthétiser de nouveaux polymères conjugués électro-déficients pour développer des transistors à effet de champ organiques (OFETs) de type n avec de bonnes propriétés de transport de charges stables à l'air, ces composés pourront être dopés pour préparer des thermoélectriques (OTHEs) de type n. Les polymères conjugués ciblés doivent avoir des propriétés telles que : un faible gap électronique, une affinité électronique importante et donc un faible niveau de la LUMO, une bonne solubilité, une stabilité à l'ambiant et une bonne π-agrégation avec une orientation « edge-on » de l'empilement des chaînes. La stratégie donneur-accepteur est appliquée pour obtenir une faible bande interdite avec l'unité benzo[1,2-b: 4,5-b′]-dithiophène-2,6-dione (BDTD) comme accepteur associé à deux thiophènes fonctionnalisés par une chaîne alkyle. La synthèse convergente, qui utilise trois synthons, permet de changer le type de chaînes sur les unités aromatiques pour atteindre les propriétés ciblées, comme d'augmenter la solubilité, la stabilité ou l'organisation moléculaire. Un premier polymère fonctionnalisé avec des chaînes alkyles linéaires a été obtenu. Toutefois, le manque de solubilité et de stabilité ne permettent pas de l'isoler et de l'étudier. Ainsi, en perspective à ce travail, les chaînes branchées étendues seront utilisées pour augmenter la solubilité des intermédiaires et ainsi améliorer la synthèse et la pureté des polymères.

Mots clés : polymères conjugués, métallooligomères, synthèse organique, thermoélectriques organiques, cellules solaires organiques, transistors à effet de champ organiques.

  Acknowledgments: ........................................................................................................... Table of contents : ............................................................................................................ List of Abbreviations: ........................................................................................................ General Introduction ....................................................................................................... Chapter I ......................................................................................................................... I. Conjugated Polymers: .......................................................................................................

  [1,2-b:4,5-b']dithiophene-2,6-dione BDT: Benzodithiophene BTz : Benzo(2,1,3)thiadiazole BT: Bithiophene BBT: Bibenzothiophene BHJ: Bulk heterojunction BTI: Bithiophene imide BDFD: Benzodifurrandione BDD: 1,3-bis(4-(2-ethylhexyl)thiophen-2-yl)-5,7-bis (2-alkyl)benzo[1,2-c:4,5-c′]dithiophene-4,8-dione BN-Py: B-N bridged bipyridine C CsCO3: Cesium carbonate C: Speed of light CDT: Cyclopentene dithiophene D D: Donor D/A: Donor/ Acceptor DPP: Diketopyrrolopyrrole DIAD: Diisopropyl azodicarboxylate DMF: N,N-dimethylformamide DMSP: Dimethylsulfoniopropionate DMAc: Dimethylacetamide DCM: Dichloro methane DMSO: Dimethyl sulfoxide DCTB: 2-[(2E)-3-(4-tert-butylphenyl)-2-methylprop-2-enylidene]malononitrile DIPA: Diisopropanolamine DMBI-H: 4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl)dimethyl amine E Eg opt : Optical band gap Eg elec : Electric band gap ETL: Electron transporting layers E: Charge carrier Et3N: Triethylamine eq.: Equivalent(s) EA: Electron affinity F F4TCNQ: 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane FF: Fill factor G GPC: Gel permeation Chromatography GIWAXS: Grazing incident wide-angle X-ray scattering H HTL: Hole transporting layer HOMO: Highest occupied molecular orbital H2SO4: Sulfuric acid h: Planck constant I IP: Ionization potential Isc: Short-circuit current density ICL: nterconnecting layer K K2CO3: Sodium carbonate L LDA: Lithium diisopropylamide LUMO: Highest occupied molecular orbital M MO: Molecular orbital MALDI-Tof: Matrix Assisted Laser Desorption Ionization -Time of Flight m-CPBA: meta-chloroperoxybenzoic acid Me2S2: Dimethyl disulfide MeOH: Methanol Mn: Number averaged molecular weight MgSO4: Magnesium sulfate N NMR: Nuclear magnetic resonance spectroscopy NDI: Naphthalenedicarboximide Nu: Nucleophile NFAs: Non-Fullerene acceptors NBS: N-Bromosuccinimide NaOAc: Sodium acetate O OFET: Organic Field-Effect Transistor OTHE: Organic thermoelectrics OLED: Organic light emitting diode OSC: Organic solar cell OPV: Organic photovoltaic -OR: Alkoxide P PA: Polyacetylene PEDOT: Poly(3,4-ethylenedioxythiophene) PPY: Polyparaphenylene PPV: poly(phenylene vinylene PT: polythiophene PTbT: Polythieno[3,4-b]thiophene PITN: Polyisothianaphthene PTs : Polythiophenes P3ATs: Poly(3-alkylthiophene)s PTP: Poly-(thieno(3,4-b) pyrazine) PC: Polycyclic Ppv: Poly(phenylenes PEDOT: Poly(3,4-ethylenedioxythiophene) PDQT: DPP quaterthiophene polymer Pd: Palladium Pd(OAc)2: Palladium acetate PtBu2Me-HBF4: Di-tert-butyl(methyl)phosphonium tetrafluoroborate PCE: Power conversion effeciency Pmax: Maximum power Pin: Incident power P3HT: Poly (3-hexylthiphene) PC61BM: (6,6)-phenyl-C61-butyric acid methyl ester PHJ: Planar heterojunction PDI: Perylene diimide P-TSA: p-Toluenesulfonic acid PSS: Polystyrene sulphonic acid Pd(dba2)3: Tris(dibenzylideneacetone)dipalladium(0) P(o-tolyl)3: Tri(o-tolyl)phosphine Pd(PPh3)2Cl2: Bis(triphenylphosphine)palladium Q Vinylthiophene TPD: Thieno[3,4-c]pyrrole-4,6-dione TBA-Cl: Tetrabutylammonium chloride THF: Tetrahydrofuran TCO: Transparent oxide Td: Decomposition temperature TLC: Thin Layer Chromatography TMS: Tetramethylsilane TBAF: Tetra-n-butylammonium fluoride TPBT: Dithienothiophen[3,2-b]-pyrrolobenzothiadiazole U UV-Vis: ultraviolet-visible V Voc: Open-circuit voltage Vmax: Maximum voltage VG: Gate voltage VT: Threshold voltage VDS: Source/ drain voltage Symbols: 𝝀 abs (onset) : Onset absorption wavelength 𝝀abs (max) : Maximum absorption wavelength 𝝀exc: Excitation wavelength ε𝝀 : Absorption capacity Ɖ: Dispersity µe: Electron carrier mobility µh: Hole carrier mobility σ: Electrical conductivity ρ: Electrical resistance. K: Electrical resistance δ: Chemical shift Ψ:

Figure 1 :

 1 Figure 1: The different structures of molecular orbitals in ethylene

  22

Figure 5 :

 5 Figure 5: Development of the band gap as the number of repeating units of the thiophene monomer 23

  S. Stafström, K.A. Chao, Phys. Rev. B, 1984, 30, 2098-2103 27 J.L. Bredas, G.B. Street, Acc. Chem. Res., 1985, 18: 309-315 3.1.

  30

Figure 8 :

 8 Figure 8: Electronic band gap and exciton band formed in conjugated polymers.

Figure 9 :Figure 10 :

 910 Figure 9: Calculating the 𝝀abs (onset) from the UV-Vis spectroscopy absorption spectrum

( 4 -

 4 (1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl)dimethyl amine ( N-DMBI-H) and trisaminomethane (TAM) (Figure13).38

Figure 13 :

 13 Figure 13: Some examples of p-type and n-type dopants

Figure 14 :

 14 Figure 14: Structure of PTbT homo polymer

Figure 17 :

 17 Figure 17: Chemical structures of electron-deficient nitrogen-based units

Figure 21 :

 21 Figure 21: Chemical structures of unsubstituted 2,5-coupled PT, regioregular P3AT (top) and regioirregular P3AT (bottom)

Figure 23 :

 23 Figure 23: Structure of polymers with the low band gap

Figure 24 :

 24 Figure 24: The two forms of covalent bond for achieving planarity in conjugated polymers.

Figure 28 :

 28 Figure 28: Structure of polythiophene derivatives with the low band gap

Figure 30 :

 30 Figure 30: Some examples of poly(2,7-carbazole)s

Figure 31 :

 31 Figure 31: Examples of polysilol derivatives

Figure 34 :

 34 Figure 34: Conjugated polymers with noncovalent bonds

Figure 35 :

 35 Figure 35: Conformation of DPP derivatives using different aryl flanking units

Figure 37 :

 37 Figure 37: Structures of planar conjugated polymers via Sulfur-Oxygen bonds

Figure 39 :

 39 Figure 39: HOMO-LUMO splitting in covalently bound donor-acceptor pairs 104

Figure 40 :

 40 Figure 40: Structure of PTB polymers

  106

Figure 41 :

 41 Figure 41: Some examples of different types of side chains 106

Figure 42 :

 42 Figure 42: General chemical Structure of branched alkyl side chain

Figure 43 :

 43 Figure 43: Structure of P3AT-R polymers

Figure 44 :

 44 Figure 44: Structure of P[T3(R)-il] polymers

Figure 45 :

 45 Figure 45: CDT-BTZ conjugated polymer with different type of alkyl side chains

Figure 47 :

 47 Figure 47: Some conjugated polymers functionalized with alkyl side chains

Figure 48 :

 48 Figure 48: PQA2T chemical structure functionalized with different branched alkyl chain with different spacer length

Figure 49 :

 49 Figure 49: Conjugated polymers with different functionalization position with their charge mobility

  and polymers based on bithiophene-thienothiophene backbone, poly(2-(3,3-bis(2-(2-(2-methoxyethoxy) ethoxy)ethoxy)-[2,20-bithiophen]-5-yl)thieno[3,2-b]thiophene)s P(g2T-TT) with propylene glycol (Figure 50). 124

Figure 50 :

 50 Figure 50: Conjugated polymers with oligoether side chain

Figure 51 :

 51 Figure 51: Structure of PNDIF-TVT conjugated polymer

  130

Figure 52 :

 52 Figure 52: (a) Schematic presentation of charge transport model in lamellae stacking conjugated polymers; (b) face-on orientation; (c) edge-on orientation 131

Figure 53 :

 53 Figure 53: Conjugated polymers with fluorinated side chains

Figure 55 :

 55 Figure 55: The mechanism of oxidative polymerization for thiophene and pyrrole based conjugated polymers

Figure 57 :

 57 Figure 57: Typical polymerization reaction for D-A polymerization using Suzuki coupling 139

Figure 58 :

 58 Figure 58: Polymerization example with Stille coupling

Figure 59 :

 59 Figure 59: Polymerization via Sonogashira coupling reactions

Figure 60 :

 60 Figure 60: Heck coupling for polymer-polymer conjugation method 144 (TBA: tetrabutylammonium chloride)

Figure 61 :

 61 Figure 61: Negishi and Kumada coupling for the synthesis of poly(3-alkylthiophene)s 139

Figure 63 :

 63 Figure 63: Polymers obtained by DHAP in the literature148,149,150

Figure 66 :

 66 Figure 66: Copper-catalyzed alkynyl ligand exchange

Figure 67 :

 67 Figure 67: Some applications of conjugated polymers

Figure 68 :

 68 Figure 68: First satellite solar cell 162

  163

  159 S.S. Rais, N.I.M. Enzai, N. Ahmad, N. Ahmed, R. Darus, Z. Jusoh, N.N.S.N. Dzulkefli, S.A.C. Kar, S. Mohamed, N.N. Mahzan, K.S.S.K.M. Noh, H. Husni, Journal of Fundamental and Applied Sciences, 2017 -ajol.info 160 D.A. Kleinman, US Patent, 1965, 3, 175, 929 161 M.A. green, K. Emery, Y. Hishikawa, W. Warta, Progress in Photovoltaics ,2009 162 Le photovoltaïque pour satellite, 2013-Solarpedia, http://fr.solarpedia.net/wiki/index.php 163 G. Li, W.-H. Chang, Y. Yang, Nat. Rev. Mater. 2017, 2, 17043.

Figure 69 :

 69 Figure 69: Current-tension graph of solar cellsThe first and second generations of solar cells are made up of silicon and cadmium telluride (CdTe) or copper indium gallium selenide/sulfide (CIGS) as absorbers. The PCE of inorganic solar cells reaches 47 %. They are efficient, but they need high requirements during their production, such as typical thin film deposition techniques of CdTe, vapor-transport deposition and close-spaced sublimation.164

Figure 70 :

 70 Figure 70: The first silicon solar cell 165

Figure 71 :

 71 Figure 71: Sample of organic solar cells 168

Figure 73 :

 73 Figure 73: The different configurations of organic solar cells

Figure 74 :

 74 Figure 74: Single active layer OSCs configuration

Figure 75 :

 75 Figure 75: The different bilayer active layer, (a) PHJ OSCs and (b) BHJ OSCs

  178 L. Hong, H. Yao, Y. Cui, P. Bi, T. Zhang, Y. Cheng, Y. Zu, J. Qin, R. Yu, Z. Ge, J. Hou, Adv. Mater., 2021, 2103091 179 G. Yu, J. Gao, J. C. Hummelen, F. Wudl and A. J. Heeger, Science, 1995, 270, 1789-1791. 180 G. J. Hedley, A. Ruseckas and I. D. W. Samuel, Chem. Rev., 2017, 117, 796-837.vertical segregation. The ideal morphology is interpenetrated donor and acceptor as illustrated in figure76. This morphology increases exciton dissociation, charge generation and collection to the electrode. Hence, improving vertical segregation is a key step to enhance the physical properties in organic solar cells.

Figure 76 :

 76 Figure 76: D/A interface using vertical segregation

Figure 79 :

 79 Figure 79: Electronic structures of donor and acceptor with some key parameters in organic solar cells

Figure 80 :

 80 Figure 80: The favored face-on orientation and unfavored edge-on orientation of conjugated polymers in a solar cell

  189 R. L. Uy, S. C. Price, W. You, Macromol. Rapid. Comm., 2012, 33, 1162 190 W. W. Li, K. H. Hendriks, W. S. C. Roelofs, Y. Kim, M. M. Wienk, R. A. J. Janssen, Adv. Mater., 2013, 25, 3182 191 N.S. Sariciftci, L. Smilowitz, A.J. Heeger, F. Wudl, Science, 1992, 258, 1474

Figure 81 :

 81 Figure81: Some examples of fullerene derivatives.192

  201

  200 H. Sun, F. Chen, Z.-K. Chen, Materials Today, 2018, 24, 94-118 201 Q. Fan, H. Fu, Z. Luo, J. Oh, B. Fan, F. Lin, C. Yang, A. K.-Y. Jen, Nano Energy, 2022, 92, 106718

Figure 85 :

 85 Figure 85: Polymeric NFAs used in high performance organic solar cells.

Figure 88 :

 88 Figure 88: The structure of PM6 NFAs used in the achieving the best PCE in organic solar cells

  217

Figure 91 :

 91 Figure 91: Zn metallopolymer derivatives

Figure 93 :

 93 Figure 93: Structure for polymetallayne

Figure 94 :

 94 Figure 94: The DPP based metallooligomers synthesized by Zhan, Wong and al. 220

Figure 95 :

 95 Figure 95: The two strategies followed to improve the properties of P1'

  224Y. Yuan, T. Michinobu, J. Oguma, T. Kato, K. Miyake, Macromol. Chem. Phys., 2013, 214, 1465-1472

Figure 97 :

 97 Figure 97: The general scheme for low band gap metallooligomers

Figure 98 :

 98 Figure 98: The synthesis overview of main targets of chapter 2

Figure 99 :

 99 Figure 99: The 31 P{ 1 H} NMR spectrum of PA of short (Mn = 12-13 Kg.mol -1 ) and long chains (Mn=23-24 Kg.mol -1 )

Figure 100 :

 100 Figure 100: Comparison of GPC chromatograms of PA between condition 1, short chains, Mn=12-13 Kg.mol -1 and condition 2, long chains, Mn=23-24 Kg.mol -1

  b Ha and Hb refer to the first proton nearby the DPP acceptor unit and the first proton nearby the triple bond. PA was analyzed with MALDI-TOF/MS with the 2-[(2E)-3-(4-tert-butylphenyl)-2methylprop-2-enylidene]malononitrile (DCTB) matrix by Julie Hardouin, PBS, PISSARO, Rouen. The spectrum is represented in figure 101. It displays ion series from m/z 1000 to 9000 with mass gap of 1360-1362 Da, which is equal to molecular mass of the repeating unit.

Figure 101 :

 101 Figure 101: MALD-TOF spectrum of PA with the DCTB matrix

Figure 102 :

 102 Figure 102: The absorption spectra of L1', LA, P1' and PA in CH2Cl2

Figure 103 :

 103 Figure 103: The absorption spectra of P1' and PA on thin film

Figure 104 :

 104 Figure 104: The bands electronic structure of P1', PA (donors) and fullerene acceptors

Figure 105 :

 105 Figure 105: the structures of PC71BM and MCzM acceptors

Figure 106 :

 106 Figure 106: Normalized absorption (black), excitation (blue) and fluorescence (red) spectra of PA in CH2Cl2 (A) and drop-casted thin film (C), and of MCzM in CH2Cl2 (B) and drop-casted thin film (D).

Figure 107 :

 107 Figure 107: Time-dependence of the absorption spectra of PA in CH2Cl2 upon irradiation at 623 nm (flux power density = 19.7x10 3 W/m 2 ). Note that the flux density at AM 1.5 is 1 x 10 3 W/m 2 ).

Figure 108 :

 108 Figure 108: The absorption spectra of L1', LA and LB in CH2Cl2

Figure 110 :

 110 Figure 110: The general scheme of low band gap metallooligomers developed in strategy 2.

Figure 113 :

 113 Figure 113: The absorption spectra of P2' and PC on thin film Cyclic voltammetry was carried by Muriel Durandetti from COBRA laboratory, Rouen. The results confirm the narrow band gap of Eg elec = 1.42 eV, which is close to the calculated

Figure 114 :

 114 Figure 114: The electronic structure of P2', PC and PCBM Table 10: The optical and electrochemical analysis data of P2', PC and their corresponding ligands.

Figure 115 :

 115 Figure 115: The impact of the side chains with the function Y The global synthesis of functionalized metallooligomer PD is illustrated in scheme 8. The strategy is to insert functionalized EDOT (EDOT-Me-R-OY) on DPP intermediate 3 after a Stille coupling reaction. It starts with the synthesis of the key synthon EDOT-MeO-R-OP from racemic (R/S)-EDOT-MeOH and enantiomeric pure (R)-EDOT-MeOH. The key synthon is represented in figure 116. It is composed of a spacer R terminated by a protected alcohol OP. The function Y could be attached to the alcohol function after a Williamson or esterification reaction. Then, depending on the nature of the function Y and its compatibility with the reaction conditions, a pre-or post-functionalization could be made as described in scheme 11. If function Y is compatible with bromination and basic medium with Sonogashira reaction as alkyl or ethylene glycol chain, the pre-functionalization could be carried out. However, if Y is composed of sensitive, fragile function, molecules like aromatic ring or siloxane chain sensitive to bromination or base respectively, a post-functionalization could be applied which use the generic synthon EDOT-MeO-R-OP. After the deprotection, the Y function could be attached on the alcohol functions after an O-alkylation or esterification.

Figure 118 :

 118 Figure 118: The structure of different metallooligomers synthesized in this thesis.

Figure 119 :

 119 Figure 119: Structure of functionalized EDOT contained metallooligomer PD Moreover, new type of metallooligomers using one unit of EDOT per monomer as 26' intermediate could be synthesized (Scheme 19) to study the impact of the quantity of organizing groups on the charge mobility and solar cell performance.

Figure 120 :

 120 Figure 120: Applications of conjugated polymers

Figure 122 :

 122 Figure 122: Structure of thermoelectric device

  262 D. Enescu, E.O. Virjoghe, Renewable and Sustainable Energy Reviews, 2014, 38, 903-916 263 G. Min, D.M. Rowe, Energy Convers Manag., 2000, 2(41), 163-71

Figure 123 :

 123 Figure 123: Graph showing the coupled dependence of the various TE properties on carrier concentration 265

Figure 124 :

 124 Figure 124: Examples of p-type conjugated polymers

Figure 125 :

 125 Figure 125: Structure of building blocks of n-type conjugated polymers.

Figure 128 :

 128 Figure 128: Structure of n-type conjugated polymers with low LUMO level

  Among the n-dopant in organic thermoelectrics PyB, 291 (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl)dimethyl amine (N-DMBI-H) and trisaminomethane (TAM) (Figure129).292

Figure 129 :

 129 Figure 129: common n-dopant in organic thermoelectrics

Figure 131 :

 131 Figure131: Edge-on orientation in organic thermoelectrics300

Figure 132 :

 132 Figure 132: The effect of doping on molecular organization of conjugated polymers 283

Figure 133 :

 133 Figure 133: N-type conjugated polymers with remarkable stability

  128

Figure 135 :

 135 Figure 135: (a) Polymers synthesized by T. Heiser and al, (b) polymers synthesized by Fréchet and al.

  315

Figure 137 :

 137 Figure 137: Examples of conjugated polymers with alkyl side chain with different length of spacer

Figure 138 :

 138 Figure 138: Examples of n-type conjugated polymers with high µe Therefore, perfluoroalkyl side chains allow us to have stable n-type low band gap conjugated polymer under ambient conditions with high charge enhanced charge mobility. According to the literature, Perfluoroalkyl and ether perfluoroalkyl PEDOT and ester analogue are other examples of conjugated polymers functionalized with perfluoroalkyl side chains in

  320 A. Benedetto, M. Balog, H. Rayah, F. Le Derf, P. Viel, S. Palacin, M. Sallé, Electrochimica Acta, 2008, 53, 3779-3788 321 M-H. Lee, M. Kang, H-G. Jeong, J-J. Park, K. Hwang, D-Y. Kim, Macromol. Rapid Commun., 2018, 39, 1800431 1.8.3. Ethylene Glycol polar group:

Figure 142 :

 142 Figure 142: The structure of an organic field effect transistors based on OSC (organic semiconductor)

  327

  326 Y.Zhao, Y. Guo, Y. Liu, Adv. Mater. 2013, 25, 5372-5391 327 J. Yang, Z. Zhao, S. Wang, Y. Guo, Y. Liu, Chem, 2018, 4(12), 2748-2785

Figure 143 :

 143 Figure 143: The principle of an OFET

Figure 144 :

 144 Figure 144: N-type conjugated polymer with high electron mobility

Figure 145 :

 145 Figure 145: N-type donor-acceptor conjugated polymers

Figure 146 :

 146 Figure 146: The chemical structure of the conjugated polymer DG90

  ) and oxidation (Eox onset ). HOMO and LUMO energies calculated with the equation EHOMO= -(Eox onset + 4.73) eV, ELUMO= -(Ered onset + 4.73) eV. b Eg elec. = ELUMO-EHOMO (eV). c The optical band gap in thin film.The hole and electron mobilities of DG90a and DG90b have been measured on OFET device by Pr. Thomas Heiser from ICUBE laboratory at Strasbourg (Figure149).

Figure 149 :

 149 Figure 149: The hole and electron mobilities of DG90a and DG90b

Figure 153 :

 153 Figure 153: The mechanism of the cyclization reaction in the synthesis of intermediate 30

Figure 154 :

 154 Figure 154: The structure of different synthons C

Scheme 28 :

 28 Scheme 28: The synthesis of di stannic EDOT-R1 (Synthon C2)36

Figure 155 :

 155 Figure 155: The strategy followed in literature to functionalize EDOT

Figure 156 :

 156 Figure 156: Routs followed to functionalize EDOT with perfluorinated chains (Synthon C3)

Figure 157 :

 157 Figure 157: The GPC chromatograms of DG90a (DG90-CHCl3), DG90b (DG90-CB) and T1 for the two conditions

Figure 158 :

 158 Figure 158: The next approach toward the synthesis of new family of conjugated polymers T4-T6.

Figure 159 :

 159 Figure 159: The retrosynthesis of the electro-deficient conjugated polymer T4

Figure 160 :

 160 Figure 160: The methodology of strategy 1

Figure 161 :

 161 Figure 161: The structure of metallooligomers PA and PB

Figure 162 :

 162 Figure 162: The structure of metallooligomers P2' and PC

Figure 163 :

 163 Figure 163: The structure of conjugated polymers DG90 and T1

  348 (a) Scattergood, P.A.; Delor, M.; Sazanovich, I.V.; Bouganov, O.V.; Tikhomirov, S.A., Stasheuski, A.S.; Parker, A.W.; Greetham, G.M.; Towrie, M.; Davies, E.S.; Meijer, A.J. Electron transfer dynamics and excited state branching in a chargetransfer platinum (II) donor-bridge-acceptor assembly. Dalton Trans., 2014, 43, 17677-17693. (b) Ueda, M.; Ueno, T.; Suyama, Y.; 31 Ryu, I. Synthesis of 2, 3-disubstituted indenones by cobalt-catalyzed [3+2] annulation of omethoxycarbonylphenylboronic acid with alkynes. Chem. Commun. 2016, 52, 13237-13240. 349 (a) Bauernschmitt, R.; Ahlrichs, R. Treatment of electronic excitations within the adiabatic approximation of time dependent density functional theory. Chem. Phys. Lett. 1996, 256, 454-464. (b) Becke, A.D. Density-functional thermochemistry. III. The role of exact exchange. J. Chem. phys. 1993, 98, 5648-5652. (c) Casida, M.E.; Jamorski, C.; Casida, K.C.; Salahub, D.R. Molecular excitation energies to high-lying bound states from time-dependent density-functional response theory: Characterization and correction of the time-dependent local density approximation ionization threshold. J. Chem. Phys. 1998, 108, 4439-4449. 350 (a) Binkley, J.S.; Pople, J.A.; Hehre, W.J. Self-consistent molecular orbital methods. 21. Small split-valence basis sets for first-row elements. J. Am. Chem. Soc., 1980, 102, 939-947. (b) Dobbs, K.D.; Hehre, W.J. Molecular orbital theory of the properties of inorganic and 32 organometallic compounds 4. Extended basis sets for third-and fourth-row, main-group elements. J. Comput. Chem., 1986, 7, 359-378. (c) Dobbs, K.D.; Hehre, W.J. Molecular orbital theory of the properties of inorganic and organometallic compounds 5. Extended basis sets for first-row transition metals. J. Comput. Chem. 1987, 8, 861-879. (d) Dobbs, K.D.; Hehre, W.J.Molecular orbital theory of the properties of inorganic and organometallic compounds. 6. Extended basis sets for secondrow transition metals. J. Comput. Chem., 1987, 8, 880-893. (e) Gordon, M.S.; Binkley, J.S.; Pople, J.A.; Pietro, W.J.; Hehre, W.J. Self-consistent molecular-orbital methods. 22. Small split-valence basis sets for second-row elements. J. Am. Chem. Soc. 1982, 104, 2797-2803. (f) Pietro, W.J.; Francl, M.M.; Hehre, W.J.; DeFrees, D.J.; Pople, J.A.; Binkley, J.S. Self-consistent molecular orbital methods. 24. Supplemented small split-valence basis sets for second-row elements. J. Am. Chem. Soc., 1982, 104, 5039-5048.reported in parts per million. The following notation are used to designate the NMR signals; s: singlet, d: doublet, t: triplet, m: multiplet, br: broad.High-resolution ESI-MS (HR-MS). Samples were analyzed by ESI-MS on a high-resolutionand high-accuracy mass spectrometer (LTQ-Orbitrap Elite, Thermo Scientific) in positive ion mode. Samples were dissolved in dichloromethane at a concentration between 1 and 5 pmol/µL according to the sample. They were infused at a flow rate of 3 µL/min. The following experimental conditions were applied: spray high voltage, 3 kV; source temperature, 350°C; sheath gas flow rate, 10. External calibration was carried out using the Pierce LTQ Velos ESI positive ion calibration solution. The resolution was set at 240 000 at m/z 400.Gel permeation chromatography (GPC) were carried out on the GPC prominence Shimadzu with UV-visible detector SPD-20AV (Double wavelength), A metallooligomer concentration of 1 mg/mL were used and the solution were filtered through a 0.45 micron filter before injection. Average molecular weights (Mw, Mn) were determined by GPC against polystyrene standards. THF was used as eluents with a flow rate of 1ml/min. Attenuated total reflection infrared (ATR IR) spectra were recorded on powders using Spectrum Two from PerkinElmer. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) Experiments were performed by MALDI-TOF/MS (Ultraflex, Bruker Daltonique) in positive ion mode and in reflectron or linear modes. The ion-accelerating voltage was 20 kV. One µL of sample was deposited on the target and was covered with the matrix. Dithranol and trans-2-[3-(4-tert-Butylphenyl)-2-methyl-2-propenylidene]malononitrile (DCTB) were chosen.

1 H

 1 NMR (400 MHz, DMSO) δ (ppm): 11.24 (s, 1H), 8.23 (s br., 1H), 7.96 (br., 1H), 7.30 (s br., 1H).

13 C

 13 NMR (400 MHz, DMSO) δ (ppm): 161.61, 136.14, 132.63, 131.25, 130.78, 128.69, 108.54. 2,5-Dinonyl-3,6-bis(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4-dione (2) 222 The procedure was inspired from the literature, S. Jung Park , J. E. Jung , M. K. Kang , Y. H. Na, H. H. Song , J. W. Kang , N. S. Baek , T.-D. Kim , Synthetic Metals, 2015, 203, 221. In a 250 mL flame-dried schlenk, 1

1 H

 1 NMR (500 MHz, CDCl3) δ (ppm): 8.86 (dd, 2H, J = 4.0 Hz, J = 1.0 Hz), 7.57 (dd, 2H, J = 5.0 Hz, J = 1.1 Hz), 7.21 (t, 2H, J = 4.5 Hz), 4.0 (t, 4H, J = 8.0 Hz), 1.74-1.68 (m, 4H), 1.41-1.36 (m, 4H), 1.34-1.29 (m, 4H), 1.27-1.23 (m, 19H), 0.84 (m, 6H).

  The procedure was inspired from the literature, Catherine Kanimozhi, Nir Yaacobi-Gross, Edmund K. Burnett, Alejandro L. Briseno, Thomas D. Anthopoulos, Ulrike Salznerd, Satish Patil, Phys. Chem.Chem. Phys., 2014, 16, 17253-17265. In a 50 mL round bottom flask wrapped with aluminum foil to prevent light, 2

  MALDI-TOF (dithranol) calc. for C40H46Br2N2O2S4 (5) m/z = 872.08, measured [M+2] + m/z = 874.10 calc. for C40H47BrN2O2S4 (5') m/z = 794.17, measured [M+2] + m/z = 796.19. c]pyrrole-1,4-dione (LA) 234 The procedure was inspired from the literature, Yuping Yuan, Tsuyoshi Michinobu, Jun Oguma, Takehito Kato, Kunihito Miyake, Macromol. Chem. Phys. 2013, 214, 1465-1472. In flamed-dried Schlenk wrapped with aluminum foil to prevent light and under argon atmosphere, the crude product 5 and 5' (200 mg) is dissolved in the mixture tetrahydrofuran/ diisopropylamine: 25mL/ 25mL. The solution was degassed with argon stream bubbling into the solution. Then CuI (6.0 mg, 31.5 μmol) and PdCl2(PPh3)2 (33.0 mg, 47.0 μmol) were added. Then, trimethylsilylacetylene (TMSA), 98% purity (88.0 mg, 0.896 mmol) was added. The mixture was heated at 70 °C for 3 hours and monitored by TLC (eluent: CH2Cl2/pentane: 40/60, Rf= 0.55). The solution was evaporated under reduced pressure and the crude product was purified by column chromatography on silica gel using pentane/CH2Cl2 (60/40) as eluent to provide L as a dark blue solid (98 mg, 107.75 μmol, 41 % yield from 4). 1 H NMR (500 MHz,CDCl3) δ (ppm): 8.92 (d, 2H, J = 4.2 Hz), 7.30 (d, 2H, J = 4.2 Hz), 7.16 (m, 4H), 4.1 (t, 4H, J = 7.8 Hz), 1.75 (m, 5H*), 1.44-1.19 (m, 65H*), 0.84 (m, 18H*) *: nonyl side chains on DPP + supplementary hydrogens from 1-bromononyle residue, 0.24 (s, 18H), 0.07 (TMS residue).

- 1 ) 3 3

 13 Scheme S2: the synthetic route of LB from compound 3

7 )

 7 The procedure was inspired from the literature, Catherine Kanimozhi, Nir Yaacobi-Gross, Edmund K. Burnett, Alejandro L. Briseno, Thomas D. Anthopoulos, Ulrike Salznerd, Satish Patil, Phys. Chem. Chem. Phys., 2014, 16, 17253-17265. |In a 25 mL round bottom, 6 (100 mg, 0.095 mmol) was dissolved in CH2Cl2 (20 mL) the solution was

  In flamed-dried schlenk, to a solution of the crude product 7 (100 mg) in a degazed solvents mixture iPr2NH/THF: 20 mL/20, CuI (2 mg, 10.5 μmol) and PdCl2(PPh3)2 (20 mg, 28.5 μmol) were added. Then trimethylsilylacetylene (TMSA) (69 mg, 0.704 mmol) was added.

Scheme S4 :

 S4 Scheme S4: The synthesis of the racemic mixture of EDOT-MeOH 13

13 C( 2 , 3 -

 1323 NMR (500 MHz, CDCl3) δ (ppm): 148.6, 117.9, 97.1, 57.6 IR (neat, cm -1 ) λ 3112 (Csp3-H), 3003-2822 (Csp3-H CH3, CH2), 1570 (aromatic C=C), 1502 (C-Oether), 900-700 (aromatic C-H).HR-MS (ESI+) m/z [M+ • ] calcd. for = C6H8O2S 144.0245, found = 144.0242.To a three-necked flask equipped with an argon purge, product 10 3,4dimethoxythiophene (1.0 g, 7.0 mmol), racemic (R/S) 3-chloro-1,2-propanediol (3.87 g, 35 mmol), p-TSA (0.137 g, 0.875 mmol) and dry toluene (19 mL) were added. The reaction mixture was heated at 90 °C for 24 h. After 24 hours of reaction, the mixture was allowed to cool room temperature. The mixture was extracted with dichloromethane (2 x 15 mL). The organic fractions were combined, dried over MgSO4 and concentrated under reduced pressure. The crude product was isolated by flash chromatography (silica gel, 100 % pentane to 8/2 pentane/ CH2Cl2) to afford the product 11 (842 mg) as a colorless oil in 63 % yield. 1 H NMR (500 MHz, CDCl3) δ (ppm): 6.38 (1H, d, 4 JH-H = 3.8 Hz), 6.36 (d, 1H, 4 JH-H = 3.8 Hz) 4.38-4.34 (m, 1H), 4.27 (dd, 1H, 2 JH-H = 11.7 Hz, 3 JH-H = 2.2 Hz), 4.15 (dd, 2 JH-H = 11.7 Hz, 3 JH-H = 6.4 Hz), 3.72 (dd, 2H, 2 JH-H = 11.7 Hz, 3 JH-H = 5.1 Hz), 3.66 (dd, 2H, 2 JH-H = 11.7 Hz, 3 JH-H = 7.2 Hz) 13 C NMR (500 MHz, CDCl3) δ (ppm): 141.7 ,140.7, 100.2, 72.9, 65.6, 41.4. IR (neat, cm -1 ) λ 3113 (Csp3-H, CH3), 2919 (Csp3-H, CH2, CH), 1581 (aromatic C=C), 1184 (C-O), 900-700 (aromatic C-H). HR-MS (ESI+) m/z [M +• ] calcd. for = C7H7O2S 35 Cl 189.9855, found= 189.9854, [ 35 Cl] + = 190.9923, [ 37 Cl] + = 192.9892. Dihydrothieno[3,4-b][1,4]dioxin-2-yl)methyl Acetate (EDOT-MeOAc) (12)To a 50 mL three-necked flask, 2-(Chloromethyl)-2,3-dihydrothieno[3,4- b][1,4]dioxane -(11) (0.83 g, 4,3 mmol), CH3COONa (0.549 g, 6.54 mmol), and DMSO (13 mL) were added. The solution was stirred for for 2 h at 120 °C. The mixture was poured into distillated water (10 mL) and extracted with CH2Cl2. Then the solvent was removed under reduced pressure. The crude product was isolated by flash chromatography (aluminium oxide, neutral, 100 % pentane to 1/1 pentane/ CH2Cl2) to afford the product 12 (0.629 g) as a yellow oil in 68 % yield.

13 C

 13 NMR (500 MHz, CDCl3) δ (ppm): 170.6, 141.2, 141.0, 71.5, 65.6, 62.4. IR (neat, cm -1 ) λ 3113 (Csp3-H, CH3), 2921 (Csp3-H, CH2, CH), 1737 (C=O), 1582 (aromatic C=C), 1482 (Csp3-H), 1228-1184 (C-Oester, 2 bands), 900-700 (aromatic C-H). HR-MS (ESI+) m/z [M + H] + calcd. for = C9H11O4S 215.0378, found = 215.0373. To a 50 mL three-necked flask, (2,3-Dihydrothieno[3,4-b][1,4]dioxin-2-yl)methylAcetate -(11) (EDOT-MeOAc; 0.27 g, 1.26 mmol), was added to a solution of NaOH (0.17 g, 4.41 mmol) in distillated water (7.7 mL). The reaction mixture was refluxed for 2 h and then cooled to RT. The mixture was acidified with 8 mL 1M HCl and then extracted with CH2Cl2. The solvent was removed under reduced pressure and column chromatography (aluminum oxide, neutral, 100 % pentane to 1/1 pentane/ CH2Cl2) was performed to give the product 13 (0.2 g) as a light brown oil in 93 % yield. Exact mass m/z 172.1980. 1 H NMR (500 MHz, CDCl3) δ (ppm): 6.35 (d, 1H, 4 JH-H = 3.8 Hz), 6.34 (d, 1H, 4 JH-H = 3.8 Hz), 4.27-4.23 (m, 1H) 4.22 (dd, 1H, 2 JH-H = 6.2 Hz, 3 JH-H = 2.4 Hz), 4.09 (dd, 1H, 2 JH-H = 12.3 Hz, 3 JH-H = 8.4 Hz), 3.88 (dd, 1H, 2 JH-H = 12.3 Hz, 3 JH-H = 4.3 Hz), 3.82 (dd, 1H, 2 JH-H = 12.3 Hz, 3 JH-H = 5.1 Hz). IR (neat, cm -1 ) λ 3375 (OH), 3110 (Csp3-H, CH3), 2925 (Csp3-H CH2, CH), 1737 (C=O), 1580 (aromatic C=C), 1482 (Csp3-H), 1183 (C-O), 900-700 (aromatic C-H). HR-MS (ESI+) m/z [M + H] + calcd. for = C9H9O3S 173.0273, found = 173.0267. All the experimental procedures for the synthesis of the products 14, 15 and 16 are the same as for the synthesis of the same products in racemic version. (500 MHz, CDCl3) δ (ppm) : 6.38 (d, 1H 4 JH-H = 3.8 Hz), 6.36 (d, 1H, 4 JH-H = 3.8 Hz), 4.42-4.34 (m, 1H), 4.31-4.27 (m, 2H), 4.23 (dd, 3H, 2 JH-H = 11.7 Hz, 3 JH-H = 2.3 Hz), 4.05 (dd, 1H, 2 JH-H = 11.7 Hz, 3 JH-H = 7.3 Hz), 2.10 (s, 3H).

13 C

 13 NMR (500 MHz, CDCl3) δ (ppm): 141.6, 140.7, 100.1, 72.9, 65.4, 41.5. IR (neat, cm -1 ) λ 3113 (Csp3-H, CH3), 2919 (Csp3-H, CH2, CH), 1581 (aromatic C=C), 1184 (C-O), 900-700 (aromatic C-H). (500 MHz, CDCl3) δ (ppm): 6.36 (d, 1H, 4 JH-H = 3.7 Hz), 6.34 (d, 1H, 4 JH-H = 3.7 Hz), 4.40-4.35 (m, 1H,), 4.31-4.28 (m, 2H), 4.21 (dd, 3H, 2 JH-H = 11.7 Hz, 3 JH-H = 2.3 Hz), 4.05 (dd, 1H, 2 JH-H = 11.7 Hz, 3 JH-H = 7.3 Hz), 2.10 (s, 3H).

13 C 3 Hz, 3 3 Hz, 3

 133333 NMR (500 MHz, CDCl3) δ (ppm): 170.6, 141.2, 141.0, 71.5, 65.6, 62.4. IR (neat, cm -1 ) λ 3113 (Csp3-H, CH3), 2921 (Csp3-H, CH2, CH), 1737 (C=O), 1582 (aromatic C=C), 1482 (Csp3-H), 1228-1184 (C-Oester, 2 bands), 900-700 (aromatic C-H). , CDCl3) δ (ppm): 6.35 (d, 1H, 4 JH-H = 3.8 Hz), 6.34 (d, 1H, 4 JH-H = 3.8 Hz), 4.24 (m, 1H) 4.21 (dd,1H, 2 JH-H = 6.2 Hz, 3 JH-H = 2.4 Hz), 4.10 (dd, 1H, 2 JH-H = 12.JH-H = 8.4 Hz), 3.87 (dd, 1H, 2 JH-H = 12.3 Hz, 3 JH-H = 4.3 Hz), 3.81 (dd, 1H, 2 JH-H = 12.JH-H = 5.1 Hz).

13 C

 13 NMR (500 MHz, CDCl3) δ (ppm): 141.4, 99.8, 74.1, 65.7, 61.6. IR (neat, cm -1 ) λ 3375 (OH), 3110 (Csp3-H, CH3), 2925 (Csp3-H CH2, CH), 1737 (C=O), 1580 (aromatic C=C), 1482 (Csp3-H), 1183 (C-O), 900-700 (aromatic C-H).

( 5 -

 5 bromopentyl)oxy)(tert-butyl)dimethylsilane (17)To a 100 mL two-necked flask equipped with Argon purge, 6bromo-1-hexanol (1.0 g, 5.81 mmol) and imidazole (0.551 g, 8.1 mmol) in dry DCM (30 mL) were added. Then, tert-Butyldimrthylsilyl solution in 50 % toluene (2.46 g, 8.15 mmol) was added to the solution. The reaction mixture was stirred at RT during 20 h. The mixture was poured into distillated water (25 mL) and extracted with CH2Cl2 (2 x 20 mL). The organic phase was washed with brine, dried over MgSO4 and concentrated under vacuum. The crude product was isolated by flash chromatography (silica gel, 100 % pentane to 8/2 pentane/ CH2Cl2), to afford the product 17 (1.7 g) as a colorless oil in 98 % yield.1 H NMR (500 MHz, CDCl3) δ (ppm): 3.59 (t, 3 J = 6.45 Hz, 2H), 3.40 (t, 3 J = 6.9 Hz, 2H), 1.86 (quintet, 3 J = 6.9 Hz, 2H), 1.53 (quintet, 3 J = 6.8 Hz, 2H), 1.44 (quintet, 3 J = 7.1Hz, 2H) 1.35 (quintet, 3 J = 7.15 Hz, 2H), 0.88 (s, 9H), 0.04 (s, 6H)13 C NMR (500 MHz, CDCl3) δ (ppm): 60.0, 33.9, 32.8, 32.6, 28.0, 25.9, 25.1, 18.4, -5.2.IR (neat, cm-1 ) λ 2929 (Csp3-H, CH3, CH2), 2856 (Csp3-H, CH), 1500-800 (C-C), 1100 (C-O), 600-500 (C-Br). HR-MS (ESI+) m/z [M+H] + calcd. for C12H28OSi 79 Br = 296.1093, found = 296.1087, [ 79 Br] + = 294.1087, [ 81 Br] + = 298.1094. mL three-necked flask equipped with Ar purge, EDOT-MeOH 13 (0.2 g, 1.16 mmol), NaH (60 %) (0.46 g, 11.6 mmol), 18crown-6 (0.03 g, 0.16 mmol) and dry DMF (6 mL) were added. The mixture was stirred at RT for 1 h. Then, the product 17 (0.41 g, 1.4 mmol) was added dropwise in the mixture. After 20 h of reaction, the mixture was poured into a saturated solution of NH4Cl (15 mL)

1 H

 1 NMR (500 MHz, CDCl3) δ (ppm): 6.32 (m, 2H), 4.29 (m, 1H), 4.24 (dd,2 JH-H = 11.6 Hz,3 JH-H = 2.3 Hz, 1H), 4.0 (dd,2 JH-H = 11.6 Hz,3 JH-H = 7.6 Hz, 1H), 3.7 (dd,2 JH-H = 10.4 Hz,3 JH-H = 5.0 Hz, 1H), 3.59 (t,3 JH-H = 6.6 Hz, 2H), 3.58 (dd, 2 J = 10.4 Hz,3 JH-H = 5.9 Hz, 1H), 3.48 (t, 3 J H-H = 6.6 Hz, 2H), 1.58 (quint,3 JH-H = 6.8 Hz, 2H) 1.51 (quint,3 JH-H = 6.8 Hz, 2H), 1.34 (m, 4H), 0.89 (s, 9H), 0.04 (s, 6H).

13 C

 13 NMR (500 MHz, CDCl3) δ (ppm):  141.6, 99.6, 72.6, 72.0, 69.1, 66.2, 63.2, 32.8, 29.6, 26.0, 25.9, 25.7, 18.4, -5.2. IR (neat, cm -1 ) λ 2929 (Csp3-H, CH3, CH2), 2856 (Csp3-H, CH), 2922 (Csp3-H, CH3), 2855 (Csp3-H, CH2, CH). 1094 (C-O), 900-700 (C-Haromatic). HR-MS (ESI+) m/z [M + H] + calcd. for C19H35O4SiS = 387.2025, found = 387.2033.

13 C

 13 NMR (500 MHz, CDCl3) δ (ppm): 39.7, 39.5, 33.5, 32.1, 29.9, 29.5, 29.4, 29.3, 26.6, 22.5, 13.9-confirmation by DEPT135 et HSQC.IR (neat, cm -1 ) λ 2921 (Csp3-H, CH3), 2852 (Csp3-H, CH2, CH).HR-MS (ESI+) m/z [M -H] + calcd. for C24H48 79 Br= 415.2939, found= 415.2930, [ 79 Br] + = 413.2930, [ 81 Br] + = 417.2917.4-decylhexadecan-1-ol (21)59 Magnesium turnings (1.856 g, 95 mmol) and lithium chloride (3.36 g, 95 mmol) in a Schlenk flask was heated at 180 °C for 10 min. in vacuo. To the flask were added THF (16.6 mL) and 1,2-dibromoethane (0.13 g, 0.33 mmol), and then the mixture was refluxed for 15 sec. by using a heat gun. After cooling to 15 °C, 11-(bromomethyl)tricosane 19 (4.8 g, 11.5 mmol) was added to the mixture.

1 H

 1 NMR (500 MHz, CDCl3) δ (ppm): 6.32 (m, 2H), 4.29 (m, 1H), 4.23 (dd,2 JH-H = 11.7 Hz,3 JH-H = 2.2 Hz, 1H), 4.0 (dd,2 JH-H = 11.7 Hz,3 JH-H = 7.7 Hz, 1H), 3.7 (dd,2 JH-H = 10.4 Hz,3 JH-H = 5.0 Hz, 1H), 3.63 (t,3 JH-H = 6.6 Hz, 2H), 3.58 (dd, 2 J = 10.4 Hz,3 JH-H = 6.0 Hz, 1H), 3.49 (t,3 JH-H = 6.6 Hz, 2H), 1.58 (m, 4H), 1.37 (m, 4H).

13 C

 13 NMR (500 MHz, CDCl3) δ (ppm): 141.6, 99.7, 72.7, 71.9, 69.1, 62.2, 62.9, 32.7, 29.5, 25.8, 25.6. IR (neat, cm -1 ) λ 3361 (OH), 3111 (Csp3-H, CH3), 2930-2859 (Csp3-H, CH2, CH), 1484 (C-Oether aliphatic), 1089 (C-O), 900-700 (C-Haromatic). HR-MS (ESI+) m/z [M+H] + calcd. for C13H21O4S = 273.1161, found = 273.1162.

1 H 19 F

 119 NMR (500 MHz, CDCl3) δ (ppm): 6.28(d,4 JH-H = 3.8 Hz, 1H), 6.27 (d,4 JH-H = 3.8 Hz, 1H), 4.28-4.23 (m, 1H), 4.25 (m, 2H), 4.19 (m, 1H), 4.01 (m, 1H), 3.55 (m, 1H), 3.35 (m, 2H), 1.64 (m, 2H), 1.51 (m, 2H), 1.44 (m, 2H), 1.32 (m, 4H) Pics not good resoluted due to presence of DMSO. NMR (500 MHz, CDCl3) δ (ppm): -80.72, -119.60 (t, CF3), -121.77, -122.72, -123.43. HR-MS (ASAP+) m/z [M + • ] calcld. for C12H22O4F12S = 598.1047, found = Possibility of removal of one fluorine atom during the ionization.-Mass corresponding on C15H21O3F12S (M-HF)

  . As examples of n-type doping molecules, there are

34 C. Heiliger, B.K. Meyer, Phys. Status Solidi A 210, 2013, No. 1, 67-68 35 A I. Hofmann, R. Kroon, S. Zokaei, E. Järsvall, C. Malacrida, S. Ludwigs, T. Biskup, C. Müller, Adv. Electron. Mater., 2020, 6, 2000249 36 Y. Lu, J-Y. Wang, J. Pei, Chem. Mater., 2019, 31, 6412-6423. 37 C. Heiliger, B.K. Meyer, Phys. Status Solidi A 210, 2013, No. 1, 67-68

  and many other nitrogen-based acceptor units depicted in figure17.

52 M.C. Scharber, N.S. Sariciftci, Adv.Mater. Technol., 2021, 6, 2000857 53 X. Guo, A. Facchetti, T. J. Marks, Chem. Rev. 2014, 114, 8943-9021 54 Q. Liu, S E. Bottle, P. Sonar, Adv. Mater. 2019, 1903882 55 P. Cheng, Y. Yang, Acc. Chem. Res. 2020, 53, 1218-1228. 56 Y. Wang, T. Michinobu, J. Mater. Chem. C, 2016, 4, 6200-6214

  44

63 Y.J Cheng, S.H Yang, C.H Hsu, Chem. Rev., 2009, 109, 5868 64 R.D. McCullough, Adv. Mater., 1998, 10, 93-116 65 C.L. Chochos, S.A. Choulis, Progress in Polymer Science 36, 2011, 1326-1414 66 R.L. Elsenbaumer, K.Y. Jen, R. Oboodi, Synth. Met.1986,15, 169-174 67 R. Sugimoto, S. Takeda,H.B. Gu,K. Yoshino, Chem. Express, 1986,1, 635-638

  Lei, X. Xia, J. Wang, C. Liu, J. Pei, J. Am. Chem. Soc., 2014, 136, 2135 -2141.

	92 B. Liu, D. Rocca, H. Yan, D. Pan , JACS Au. , 2021, 1, 2182-2187
	93 C. J. Mueller, E. Gann, C. R. Singh, M. Thelakkat, C. R. McNeill, Chem.Mater., 2016, 28, 7088 -7097

Table 1 :

 1 The analysis data of characterizations carried for P1

', PA and P2'

		Mn	Ɖ	Number of units	Td
		Kg.mol -1			(°C)
	P1'	18.2	2.1	15	221
	PA	12-13	2.3	9-10	273
	P2'	6.6	11.1	3-4	261

Table 2 :

 2 The optical and electrochemical analysis data of P1', PA and P2' and their corresponding ligands Ered onset ) and oxidation (Eox onset ). HOMO and LUMO energies calculated with the equation EHOMO= -(Eox onset + 4.73) eV, ELUMO= -(Ered onset + 4.73) eV. Eg elec. = ELUMO-EHOMO (eV)

		𝝀abs (max) (ε𝝀)		𝝀abs (max)	𝝀abs (onse)	Eg opt	Eox onset	Ered onset	HOMO	LUMO	Eg elec
				In
				Solution
		nm(10 4 mol -1		nm	nm	eV	V/ESC	V/ESC	eV	eV	eV
		Lcm -1 )
	L1'	554 (3.71),	P1' 599,	719	1.72 0.65	-0.97	-5.38	-3.76	1.62
		599 (4.44)		646
	LA	347, 594	PA	337,	785	1.60 0.71	-1.00	-5.44	-3.73	1.71
		(4.89), 634		663
		(5.02)
	L2'	648 (1.42),	P2' 654,	875	1.42 0.63	-0.78	-5.36	-3.95	1.41
		669 (1.39)		718
	Onset potential (V vs SCE) for reduction (

Table 3 :

 3 Photovoltaic parameters of the optimized polymer solar cells based on P1' and P2' as donor and PC71BM as acceptor.

	polymer	Isc	µe	µh	Voc	FF	PCE
		(mA/ cm 2 )	cm 2 /Vs	cm 2 /Vs	(V)		(%)
	P1'	12.96	2.29 x 10 -4	9.93 x 10 -5	0.92	0.597	7.12 (7.01) a
	P2'	16.24	1.15 x 10 -4	2.38 x 10 -4	0.89	0.667	9.54 (9.42) a
	a average of 8 devices

Table 4 :

 4 The conditions of bromination reaction for the synthesis of intermediate 5 Macromolecules, 2015, 48, 24, 8760-8764 230 C. Kanimozhi, N. Yaacobi-Gross, E. K. Burnett, A. L. Briseno, T. D. Anthopoulos, U. Salznerd, S. Patil, Phys. Chem. Chem. Phys., 2014,16, 17253-17265 231 Manuscript sygal_fusion_28082-nos-melodie

	Entry	Source of Br	Solvent	Temperature	Duration	Yield
	1 231	NBS (2.25 eq.)	CH2Cl2	0 °C to R.T	12 h	14 %
	2	NBS (2.1 eq.)	CHCl3	0 °C to R.T	12 h	14 %
	3	Br2 (2 eq.)	CHCl3	0° C to R.T	3 h	40 %
	4	Br2 (2 eq.)	CHCl3	< 0°C	3 h	41 %

229

A. Patra, V. Agrawal, R. Bhargav, Shahjad, D. Bhardwaj, S. Chand, Y. Sheynin, M. Bendikov,

Table 5 :

 5 The best condition for the preparation of PA (Entry 2) compared to the initial condition (Entry 1)

	Entry.	LA	trans-Pt(PBu)2Cl2	CuI	temperature	Duration	Mn	Ɖ
							Kg.mol -1
	1	1.0 eq.	1 eq.	0.1 eq.	R.T	3 days	12.4	2.3
	2	1.8 eq.	1 eq.	0.5 eq.	R.T	3 days	23.8	2.8
	1.1.3. Characterizations of PA

Table 6 :

 6 The analysis data of PA

		Mn	Ɖ	Number	Td	∆δHa b	∆δHb b	31 P	JP-Pt
		(Kg.mol -1 )		of units	(°C ) a	(ppm)	(ppm)	(ppm)	(Hz)
	P1'	18.2	2.1	14-15	221	0.13	-0.38	3.96	2289
	PA	23.8	2.8	17-18	273	0.00	-0.38	3.55	2306
	a Temperature at 5 wt % loss.

Table 7 :

 7

	𝝀abs (max)	𝝀abs (max)	𝝀abs (onset)	Eg opt	Eox onset	Ered onset	HOMO	LUMO	Eg elec
	(ε𝝀)	Solution
	nm (10 4 mol -1
	Lcm -1 )	nm	nm	eV	V/ESC	V/ESC	eV	eV	eV
	L1' 554	P1' 599,	719	1.72 0.65	-0.97	-5.38	-3.76	1.62
	(3.71),599	646
	(4.44)
	LA 595 (4.89),	PA 337,	785	1.58 0.71	-1.00	-5.44	-3.73	1.71
	634 (5.02)	663
	Onset potential (V vs SCE) for reduction (Ered onset ) and oxidation (Eox onset ). HOMO and LUMO energies
	calculated with the equation EHOMO= -(Eox onset + 4.73) eV, ELUMO= -(Ered onset + 4.73) eV. Eg elec. = ELUMO-EHOMO
	(eV)

Optical and electrochemical properties data of the ligands L1', LA and the metallooligomers P1', PA

Table 8 :

 8 The different conditions for polymerization reaction of PB

Table 9 :

 9 The analysis data of characterizations carried for

P1', P2' and PC

		Mn	Ɖ	Number of	31 P	JP-Pt
		(Kg.mol -1 )		units	(ppm)	(Hz)
	P1'	18.2	2.1	14-15	3.96	2289
	P2'	6.6	11.1	3-4	3.88	2290
	PC	12	2.06	8-9	2.56	2318

  (1.48 eV) with LUMO= -3.85 eV and higher level for HOMO at -5.27 eV for PC with respect to the HOMO level of P2'. The data are listed in table 10. The bands electronic structures of PC and P2' are represented in figure114.

Absorption spectra of P2' and PC on thin film P2' PC Eg opt

Table 11 :

 11 The different conditions of the O-akylation of EDOT-MeOH for the synthesis of compound 18 from 16

	Entry	Base	Equivalents	Solvent	Temperature	Yield of 18
	1	NaH (60 %)	20	THF	R.T	0 %
	2	NaH (60 %)	4	THF	R.T	0 %
	3	NaH (60 %)	2	THF	R.T	0 %
	4	NaH (60 %)	4	THF	45-65 °C	0 %
	5	KOH (85 %)	4	THF	R.T	0 %
	6	NaH (60 %)	10	DMF	R.T	71 %

Table 14

 14

	: Promising n-type material prepared from n-doping of electron deficient conjugated
	polymer. 294
	Conjugated	σ	S	PF
	polymer/Dopant	( S cm -1 )	(µ V K -1 )	(µWm -1 K -2 )
	LPPV/ TAM	3.7 ± 0.3	-204 ± 5	33.9 ± 0.9
	LPPV/ N-DMBI-H	0.9 ± 0.2	-170 ± 3	1.7 ± 0.2
	FBDPPV/ TAM	21	-170	51
	FBDPPV/ N-DMBI-H	14	-200	28

Table 16 :

 16 The analysis data of the cyclic voltammetry of DG90

		Eox onset	Ered onset	HOMO	LUMO	Eg elec	Eg opt
		V/ESC	V/ESC	eV a	eV a	eV b	eV c
	DG90	0.61	-0.21	-5.34	-4.52	0.82	0.58
	PBDTD4T	0.22	-0.76	-5.02	-4.04	0.98	0.88
	a Onset potential (V vs SCE) for reduction (Ered onset

  , M. Baumgarten, H. Yan, K. Müllen, W. Pisula, Adv. Mater., 2016, 28, 9430-9438 337 S. Chen, B. Sun, W. Hong, H. Aziz, Y. Meng and Y. Li, J. Mater. Chem. C, 2014, 2, 2183 338 K. Kawabata, M. Saito, N. Takemura, I. Osaka, K. Takimiya., Polymer Journal, 2017, 49, 169-176

Table 17 :

 17 The different reaction conditions are used for the synthesis of intermediate 31

		Number of equivalent	Number of equivalents	Number of	Yield
		of Pd(PPh3)4	of TSn1	portions
	1	0.01	2.2	1	25 %
	2	0.05	2.2	1	34 %
	3	0.1	2.2	1	48 %
	4	0.1	4.2	4	71 %

Table 18 :

 18 The different conditions tested in the synthesis of oxidized compound

		n-BuLi	2,2,6,6-	triisopropylborate	Solvent	Temperature for	Duration
		(2.5 M)	tetramethylpip-			deprotonation
			yridine
	Ref. 2.4 eq.	2.4 eq. (No	4.7 eq.	THF	-76 °C	5 h
			distillation)
	1 2.4 eq.	2.4 eq. (No	6.55 eq.	THF	-76 °C	15 h
			distillation)
	2 2.4 eq. 2.4 eq. (Distillation)	6.55 eq.	THF	-76 °C	15 h
	3 2.4 eq. 2.4 eq. (Distillation)	6.55 eq.	THF	-76 °C	3 h
	4 2.4 eq. 2.4 eq. (Distillation)	6.55 eq.	THF	-76 °C	4 h
	5	2.4 eq 2.4 eq. (Distillation)	6.55 eq.	DMF	-76 °C	15 h
	6	2.4 eq 2.4 eq. (Distillation)	6.55 eq.	diethylether	-76 °C	15 h
	7	2.4 eq 2.4 eq. (Distillation)	6.55 eq.	Toluene	-76 °C	15 h

Table 19 :

 19 The different conditions of Williamson reaction for the synthesis of compound 37

	Entry	Base	Equivalent	Solvent	Temperature	Result
	1	NaH (60 %)	2.5	THF	R.T	Starting product
	2	NaH (60 %)	4	THF	R.T	Starting product
	3	NaH (60 %)	10	THF	R.T	Starting product
	4	NaH (60 %)	20	THF	R.T	37 + elimination product
	5	KOH 85 %	20	THF	67°C	37 + elimination product
		aq.
	6	NaH (60 %)	10	DMF	R.T	37, 40% yield +
						elimination product 37'
						5% yield

13 C NMR (500 MHz, CDCl3) δ (ppm): 161

  .59, 140.42, 135.50, 130.90, 130.02, 128.84, 107.91, 42.48, 32.10, 30.22, 29.96, 29.74, 29.49, 27.13, 22.92, 14.37.

NMR (500 MHz, CDCl3) δ (ppm): 160

  .25, 141.81, 138.11, 135.48, 135.15, 127.25, 127.11, 125.29, 124.23, 123.96, 107.16, 41.27, 30.82, 29.00, 28.68, 28.47, 28.22, 25.87, 21.65, 13.08.

	1 H NMR (500 MHz, CDCl3) δ (ppm):8.90 (d, 2H, J = 4.2 Hz), 7.31 (m, 6 H), 7.06 (t, 2H, J = 4.2
	Hz), 4.07 (t, 4 H, J = 7.7 Hz), 1.79-1.72 (m, 4 H), 1.44-1.39 (m, 4 H), 1.36-1.32 (m, 6H), 1.29-1.21
	(m, 24H), 0.84 (t, 6H).
	IR (cm -1 ): v = 3087 (v, C-H aromatic), 2921 and 2851 (w, v (N-CH2)), 1657 (w, v(C=O)).
	MALDI-tof (dithranol) calc. for C40H48N2O2S4 (4) [M + ], m/z = 716.26; measured [M + ] + m/z =
	716.26 ; T m.p (°C) =233.

13 C

  125.55, 124.93, 123.99, 108.58, 101.74, 97.09, 42.44, 31.98, 31.10, 29.62, 29.39, 29.37, 27.10, 22.82, 14.27, 1.17, 0.07 (TMS residue).

  methanol three times. Compound 6 was isolated as dark-blue solid (260 mg, 0.246 mmol, 58 % yield).

	1 H NMR (500 MHz, CDCl3) δ (ppm): 8.90 (d, 2H, J = 4.2 Hz), 7.29 (d, 2H, J = 4.2 Hz), 7.16 (s, 2H),
	6.92 (s, 2H), 4.09 (4H, m), 2.60 (4H, m), 1.82-1.20 (m, 78*), 0.87 (m, 15H*) alkyl side chains on
	DPP + supplementary hydrogens from 1-bromononyle residue.
	HRMS (ESI) Calculated for (6) C64H96N2O2S4: m/z 1052.635. Found: m/z 1053.635 [M+H] +
	Mahale et al, Chem. Phys. Lett. 2018, 696, 48-54
	(10.1016/j.cplett.2018.02.021).	In	flamed-dried
	schlenk, to a solution of 5 (300 mg, 0.422 mmol) in 30
	mL of anhydrous and degazed DMF, T-Sn freshly
	prepared (686 mg, 1.27 mmol) and Pd(PPh3)2Cl2 (30 mg, 0.042 mmol) were added. The mixture
	was heated at 80°C overnight under argon atmosphere. The reaction was monitored by TLC
	(eluent: CH2Cl2/pentane: 1/1, Rf (6) =0.6). After cooling, major part of DMF was evaporated

under reduced pressure. To the residue, 10 mL of the solvent mixture (CH3OH/CH2Cl2: 60/40) was added to precipitate the compound. The product 6 was collected after filtration and washing with

  (ppm): 161.31, 150.13, 142.40, 139.00, 136.49, 135.70, 128.49, 126.07, 125.25, 119.24, 108.46, 103.67, 96.99, 42.37, 32.02, 31.93, 30.96, 30.87, 30.14, 30.09, 29.79, 29.77, 29.76, 29.72, 29.58, 29.48, 29.46, 29.37, 29.34, 29.33, 28.72, 28.65, 28.40,28.28, 26.97, 22.79, 22.76, 21.71, 14.22, 14.21, 13.16, 1.11, 0.05 HRMS (ESI) Calculated for (LB) C74H112N2O2S4Si2: m/z 1244.715. Found: m/z 1245.833 [M+H] + The synthetic route of LCC from compound 3 124.73, 112.80, 108.31, 104.95, 98.30, 94.38, 65.09, 65.05, 42.45, 32.00, 30.16, 29.72, 29.39, 29.36, 27.04, 22.81, 14.26, 0.06.

	1 H NMR (600 MHz, CDCl3) δ (ppm): 8.90 (d, 2H, J = 4.2 Hz), 7.29 (d, 2H, J = 4.2 Hz), 7.06 (s, 2H), 4.07 (4H, m), 2.67 (4H, m), 1.82-1.20 (m, 78*), 0.87 (m, 15H*) 0.26 (s, 18H), alkyl side chains on DPP + supplementary hydrogens from 1-bromononyle residue 13 C NMR (600 MHz, CDCl3) δ Synthesis of LC 1025.364 [M+H] + Scheme S3: HRMS (ESI) Calculated for (LC) C54H68N2O6S4Si2: m/z 1024.350. Found: m/z Synthesis of functionalized EDOT intermediate:

  .36 (d, 1H, 4 JH-H = 3.7 Hz), 6.34 (d, 1H, 4 JH-H = 3.7 Hz), 4.40-4.35 (m, 1H), 4.31-4.28 (m, 2H), 4.22 (dd, 3H, 2 JH-H = 11.7 Hz, 3 JH-H = 2.3 Hz), 4.04 (dd, 1H, 2 JH-H = 11.7 Hz, 3 JH-H = 7.3 Hz), 2.11 (s, 3H).

1 H NMR (500 MHz, CDCl3) δ (ppm): 6

  HR-MS (ESI+) m/z [M-H] + calcld. for C28H53O = 381.4096, found = 381.4095. Exacat mass mesured on the ion m/z 381 compatible with the ion [M -H] + of the compound 21.

	11-(3-bromopropyl)tricosane (22)
	13 C NMR (500 MHz, CDCl3) δ (ppm): 63.6, 37.2, 33.6, 31.9, 30.1, 29.9, 29.7, 29.6, 29.5, 29.4,
	26.6, 22.7, 14.1.

IR (neat, cm -1 ) λ 3316 (OH), 2920 (Csp3-H, CH3), 2852 (Csp3-H, CH2, CH).

  36.8, 34.5, 33.5, 32.2, 31.9, 30.2, 30.1, 29.7, 29.4, 26.6, 14.1. +• ] calcld. for C26H53 79 Br= 444.3331. found = 444.3319. [ 79 Br] + = 442.3329, [ 81 Br] + = 446.3335.

13

C NMR (500 MHz, CDCl3) δ (ppm): IR (neat, cm -1 ) λ 2922 (Csp3-H, CH3), 2855 (Csp3-H, CH2, CH).

HR-MS (ESI+) m/z [M

13 C NMR (500 MHz, CDCl3) δ (ppm): 146

  .3, 96.2, 76.4, 72.2, 70.9, 70.1, 39.3, 38.2, 32.1, 31.7, 30.9, 29.9, 29.6, 29.3, 29.0, 27.8, 24.8, 22.3, 14.4. IR (neat, cm -1 ) λ 2922 (Csp3-H, CH3), 2855 (Csp3-H, CH2, CH), 1484 (C-Oether aliphat).

F. Martins, C. Felgueiras, M. Smitkova, N. Caetano, Energies,

2019, 12, 964 2 Chemistry of Nanomaterials Fundamentals and Applications, Book • 2020, https://doi.org/10.1016/C2018-0-04648-4 3 H. Mamur, Ö.F. Dilmaç, J. Begum, M.R.A. Bhuiyan, Cleaner Materials, 2021, 100030

Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications, First Edition. Edited by Srabanti Ghosh.© 2021 WILEY-VCH GmbH.

U. Salzner, J.B. Lagowski, P.G. Pickup, R.A. Poirier, Synthetic Metals, 1998, 96, 177-189.

L. Leonat, G. Sbarcea, I.V. Branzoi, U.P.B. Sci. Bull., Series B, Vol. 75, Iss. 3, 2013

E. Perzon, F. Zhang, M. Andersson, W. Mammo, O. Inganäs, M. R. Andersson, Adv. Mater., 2007, 19,

3308- 3311

Y. Lu, J-Y. Wang, J. Pei, Acc. Chem. Res. 2021, 54, 13, 2871-2883

J. J. Intemann, K. Yao, H.-L. Yip, Y.-X. Xu, Y.-X. Li, P.-W. Liang, F.-Z. Ding, X. Li and A. K. Y. Jen, Chem. Mater., 2013, 25, 3188-3195

J. Li, Y. Zhao, H. S. Tan, Y. Guo, C. A. Di, G. Yu, Y. Liu, M. Lin, S. H. Lim, Y. Zhou, H. Su and B. S. Ong, Sci. Rep., 2012, 2, 754.

B. Fu, J. Baltazar, Z. Hu, A.-T. Chien, S. Kumar, C. L. Henderson,D. M. Collard and E. Reichmanis, Chem. Mater., 2012, 24, 4123-4133

J. Yang, Z. Zhao, S. Wang, Y. Guo, Y. Liu, Chem 4, 2748-2785, December 13, 2018

X. Guo, M. Baumgarten, K. Müllen, Progress in Polymer Science, 2013, 38,1832

J.L. Bredas, J.chem.phys., 1985,42, 3808

H. Gilman, R.D. Gorsich, J. Am.Chem. Soc., 1955, 77, 6380-6381

T.T. Dang, H.M.T. Nguyen, H. Nguyen, T.N. Dung, M.T. Nguyen, W. Dehaen, Molecules, 2020, 25, 548

J. Bernstein, R.E. Davis, L. Shimoni, N-L. Chang, Angew.chem.Int.Ed.Engl, 1995Engl, , 34, 1555Engl, -1573

M.C. Scharber, N.S. Sariciftci, Adv.Mater. Technol., 2021,6, 2000857

L. Lu, T. Zheng, Q. Wu, A. M. Schneider, D. Zhao, L. Yu, Chem. Rev., 2015, 115, 12666.

J. Mei, Z. Bao, Chem. Mater., 2014, 26, 604-615

C. Grand, W. Zajaczkowski, N. Deb,C. K. Lo, J. L. Hernandez, D. G. Bucknall, K. Mü llen, W. Pisula, J. R. Reynolds, ACS Appl. Mater. Interfaces, 2017, 9, 15, 13357-13368

V. Coropceanu, J. Cornil, D. A. da Silva Filho, Y. Olivier, R. Silbey, J.-L. Brédas, Chem. Rev., 2007, 107, 926-952

W. Pisula, H. Tsao, D. Dudenko, D. Cho, S. Puniredd, Y. Zhao, A. Mavrinskiy, J. Shu, M. Hansen, M. Baumgarten, K. Mullen, Polymers, 2013, 5, 833

J. Lee, T. Marszalek, K. C. Lee, J. Kim, W. Pisula, C. Yang, Macromol. Chem. Phys., 2015, 216, 1244-1250

S. Chen, B. Sun, W. Hong, H. Aziz, Y. Meng and Y. Li, J. Mater. Chem. C, 2014, 2, 2183

K. Kawabata, M. Saito, N. Takemura, I. Osaka, K. Takimiya., Polymer Journal, 2017,49,[169][170][171][172][173][174][175][176]

Q. Wu, M. Wang, X. Qiao, Y. Xiong, Y. Huang, X. Gao, H.Li, Macromolecules, 2013, 46, 3887-3894

M. Shao, Y. He, K. Hong, C.M. Rouleau, D.B. Geohegan, K. Xiao, Polym. Chem., 2013, 4, 5270-5274.

H. Yan, Z. Chen, Y. Zheng, C. Newman, J.R. Quinn, F. Dotz, M. Kastler, A. Facchetti, Nature, 2009, 457, 679-686

M. Moser, Y. Wang, T. C. Hidalgo, H. Liao, Y. Yu, J. Chen, J. Duan, F. Moruzzi, S. Griggs, A. Marks, N. Gasparini, A. Wadsworth, S. Inal, I. McCulloch, W. Yue, Mater. Horiz., 2022, 9, 973-980

S. Mehdipour-Ataei, F. Zigheimat, European Polymer Journal, 2007, 43, 1020-1026

S. Bölke, D. Batchelor, A. Früh, B. Lassalle-Kaiser, T. Keller, F. Trilling, M. Forster, U. Scherf, T. Chassé, H. Peisert, ACS Appl. Energy Mater., 2022, 5, 12, 15290-15301

B. Kang, R. Kim, S. B. Lee, S-K. Kwon, Y-H. Kim, K. Cho, J. Am.Chem. Soc., 2016, 138, 11, 3679-3686

M. S. Chen, O. P. Lee, J. R. Niskala, A. T. Yiu, C. J. Tassone, K. Schmidt, P. M. Beaujuge, S. S. Onishi, M. F. Toney, A. Zettl, J. M. J. Fréchet, J. Am.Chem. Soc., 2013, 135, 19229-19236

B. McDearmon, E. Lim, I-H. Lee, L. M. Kozycz, K. O'Hara, P. I. Robledo, N. R. Venkatesan, M. L. Chabinyc, C. J. Hawker,Macromolecules, 2018, 51, 7, 2580-2590

C. Mattheus, G. A. de Wijs, R. A. de Groot, T. T. M. Palstra, J. Am. Chem. Soc., 2003, 125, 6323-6330.

A. Salleo, Mater. Today, 2007, 10, 38-45

S. Nishinaga, H. Mori, Y. Nishihara, Macromolecules, 2015, 48, 2875-2885

R. J. Kline, M. D. McGehee, M. F. Toney, Nat. Mater., 2006, 5, 222-228

I. Osaka, M. Saito, T. Koganezawa, K. Takimiya, Adv. Mater., 2014, 26,[331][332][333][334][335][336][337][338]

S. Chen, B. Sun, W. Hong, H. Aziz, Y. Meng, Y. Li, J. Mater. Chem. C, 2014, 2, 2183-2190

M. Collard, Adv.Mater., 2004, 16, No.2, january 16

B. Wang, S. Watt, M. Hong, B. Domercq, R. Sun, B. Kippelen, D.M. Collard, Macromolecules, 2008, 41, 5156-5165.

N.Y. Abu-Thabit, J. Chem.Educ., 2016Educ., , 93, 1606Educ., -1611

P. Morin, T. Bura, M. Leclerc, Mater. Horiz., 2016,3,[11][12][13][14][START_REF] Clayden | Organic Chemistry[END_REF][START_REF] Ravichandran | [END_REF][START_REF] Wise | Electrical and Optical Polymer Systems: Fundamentals, Methods, and Applications[END_REF][START_REF] Will | [END_REF][19][20]

Z. Bao, W. K. Chan, L. Yu, J. Am.Chem. Soc., 1995, 117, 50, 12426-12435

M. Atzori, F. Artizzu, E. Sessini, L. Marchiò, D. Loche, A. Serpe, P. Deplano, G. Concas, F. Pop, N. Avarvari, M. Laura Mercuri †, J. Name., 2013, 00, 1-3

M. Nasrollahzadeh, N. Motahharifar, F. Ghorbannezhad, N. S. S. Bidgoli, T. Baran, R. S. Varma, Molecular Catalysis, 480 (2020) 110645

L. G. Mercier and M. Leclerc, Acc. Chem. Res., 2013, 46, 1597-1605.

M. Sévignon, J. Papillon, E. Schulz, M. Lemaire, Tetrahedron Lett., 1999,40, 5873-5876.

B. Biswas, M. Sugimoto, S. Sakaki, Organometallics, 2000,19, 3895-3908.

W. Lu, J. Kuwabara and T. Kanbara, Macromolecules, 2011, 44, 1252-1255

P. Berrouard, A. Najari, A. Pron, D. Gendron, P.-O. Morin, J.-R. Pouliot, J. Veilleux, M. Leclerc, Angew. Chem., Int. Ed., 2012, 51, 2068-2071.

F. Grenier, K. Goudreau, M. Leclerc, J. Am. Chem. Soc., 2017, 139, 2816.

F. Babudri, G. M. Farinolaa, F. Naso, J. Mater.Chem., 2004, 14, 11-34

N.J. Long, C.K.Williams , Angew. Chem.Int. Ed., 2003, 42, 2586-2617

K. Sonogashira, S. Kataoka, S. Takahashi, N. Hagihara, J. Organomet. Chem., 1978, 160, 319.

F. Ullah, H. Chen, CZ. Li -Chinese Chemical Letters, 2017 -Elsevier

https://www.pinterest.com/pin/838302918135943684/

G.H. Kim, D.S. Kim, Joule, 2021, 5, 1033-1035

S. B. Mdluli, M. E. Ramoroka , S. T. Yussuf, K. D. Modibane, V. S. John-Denk, E. I. Iwuoha, Polymers, 2022, 14, 716

Z. Guo, A. K. Jena, G. M. Kim, T. Miyasaka, Energy Environ. Sci., 2022,[START_REF] Clayden | Organic Chemistry[END_REF]

S. Günes, H. Neugebauer, N.S. Sariciftci, Chemical reviews, 2007, 107, 4, 1324-1338

NREL updates interactive chart of solar cell efficiency,November 21, 2022

M. Helgesen, S.A. Gevorgyan, F.C. Krebs, ACS Publications, 2009

S. K. Hau, H.L. Yip, A. K.-Y. Jen, Polymer Reviews, 2010, 50, 474-510

X. Xu, G. Zhang, Y. Li, Peng, Q. Chin, Chem. Lett. 2019, 30, 809-825

R. Xue, J. Zhang, Y. Li, Y. Li, Small, 2018, 14, 1801793.

J. Chin., Chem. Soc., 2014, 61, 115-126

S. Garg, N. Goel, J. Phys. Chem. C, 2022, 126, 9313-9323

G. Li, R. Zhu, Y. Yang, Nat. Photon., 2012,6, 153

S. Zhang, Y. Qin, J. Zhu, J. Hou, Adv. Mater., 2018, 30, 1800868

Q. Fan, W. Su, Y. Wang, B. Guo, Y. Jiang, X. Guo, F. Liu, T. P. Russell, M. Zhang and Y. F. Li, Sci. China: Chem., 2018, 61, 531-537

T. H. Lee, Y. Dong, R. A. Pacalaj, S. Y. Park, W. Xu, J.-S. Kim, J. R. Durrant, Adv. Funct. Mater., 2022, 32, 2208001

H. Zhan, Q. Liu, S.-K. So, W.-Y. Wong, Journal of Organometallic Chemistry, 2019, 894, 1-9

W. Li, A. Furlan, W. S. C. Roelofs, K. H. Hendriks, G. W. P. van Pruissen, M. M. Wienka, R. A. J. Janssen, Chem. Commun., 2014, 50, 679-681

W. Li, K. H. Hendriks, M. M. Wienk, R. A. Janssen, Acc. Chem. Res., 2016,49, 78

L. Dou, W.-H. Chang, J. Gao, C.-C Chen, J. You, Y. Yang, Adv. Mater., 2013, 25, 825-831

K. H. Hendriks, G. H. L. Heintges, V. S. Gevaerts, M. M. Wienk, R. A. J. Janssen, Angew. Chem., Int. Ed., 2013, 52, 8341

J. Dhar, N. Venkatramaiah, Anitha A., S. Patil, J. Mater. Chem. C, 2014, 2, 3457-3466

J-C. Eloi, L. Chabanne, G.R. Whittell, I. Manners, Mater. Today, 2008, 11, 28-36

A. Verma, P. Chaudhary, R. K. Tripathi, A Singh, B. C. Yadav, Inorg Organomet Polym, 2022, 32, 2807-2826

H. Zhan, Q. Liu, S.-K. So, W.-Y. Wong, J. Organomet. Chem., 2019, 894, 1.

M.C. Scharber, D. Muhlbacher, M. Koppe, P. Denk, C. Waldauf, A.J. Heeger, C.J. Brabec, Adv. Mater., 2006, 18, 789-794

M. Nos, G. Marineau-Plante, D. Gao, M. Durandetti, J. Hardouin, P. Karsenti, G. Gupta, G. D. Sharma, P. D. Harvey, C. Lemouchi, L. Le Pluart, J. Mater. Chem. C, 2020, 8, 2363-2380

M. Jiang, H-r Bai, H-f Zhi, J-k Sun, J-l Wang, F. Zhang, Q. An, ACS Energy Lett., 2021,6,[START_REF][END_REF][2898][2899][2900][2901][2902][2903][2904][2905][2906]

Q. Liu, C-L. Ho, Y. H. Lo, H. Li, W-Y. Wong, J Inorg Organomet Polym., 2015, 25, 159.

Y. Yuan, T. Michinobu, J. Oguma, T. Kato, K. Miyake, Macromolecule.chem.phys., 2013, 214,1465-1472

A. Patra, V. Agrawal, R. Bhargav, Shahjad, D. Bhardwaj, S. Chand, Y. Sheynin, M. Bendikov, Macromolecules, 2015, 48, 24, 8760-8764

D. Liu, Q. Zhu, C. Gu, J. Wang, M. Qiu, W. Chen, X. Bao, M. Sun, R.Yang, Adv. Mater., 2016, 28, 8490

B. Fan, L. Ying, P. Zhu, F. Pan, F. Liu, J. Chen, F. Huang, Y. Cao, Adv. Mater., 2017, 29, 1703906

D. Amsallem, A. Bedi, F. Tassinari, O. Gidron, Macromol., 2020, 53, 9521-9528

S. Zhang, J Xu, B. Lu, L. Qin, L. Zhang, S. Zhen, D. Mo, J. Polym. J. Polym. Sci., Part A: Polym. Chem., 2014, 52, 1989-1999

D. Amsallem, A. Bedi, F. Tassinari, O. Gidron, Macromol., 2020, 53, 9521-9528

L. Dong, Y. Zhang, X. Duan, X. Zhu, H. Sun, J. Xu, Anal. Chem., 2017, 89, 9695-9702

S.C.Ng, H.S.O. Chan, W.-L. Yu, Journal of Materials Science Letters, 1997, 16, 809-811.

Patent : Kozlowski, R. Z., et al. Lipo-or amphiphilic scintillators and their use in assays, WIPO, W02002014290, 2002

G. Trippé, F. Le Derf, J. Lyskawa, M. Mazari, J. Roncali, A. Gorgues, E. Levillain, M. Sallé, Chem. Eur. J., 2004, 10, 6497-6509.

K. Krishnamoorthy, M. Kanungo, A.Q. Contractor, A. Kumar, Synth. Met. 2001, 124, 471-475.

S. Macher, M. Schott, M. Sassi, I. Facchinetti, R. Ruffo, G. Patriarca, L. Beverina, U. Posset, G. A. Giffin, P. Löbmann, Adv. Funct.Mater., 2019, 30, 1906254

Kohsuke Kawabata, Masahiko Saito, Itaru Osaka, and Kazuo Takimiya, J. Am. Chem.Soc. 2016, 138, 7725

K. Kawabata, M. Saito, N. Takemura, I. Osaka, K. Takimiya, Polymer Journal, 2017,49,[169][170][171][172][173][174][175][176]

L. Huang, G. Zhang, K. Zhang, Q. Peng, M. S. Wong, macromolecule, 2019, 52, 12, 4447-4457

J. Yang, Z. Zhao, S. Wang, Y. Guo, Y. Liu., chem, 2018, 4, 2748-2785

A. Polozine, S. Sirotinskaya, L. Schaeffer, Materials Research., 2014, 17(5): 1260-1267

H. J. Goldsmid, Materials 2014, 7(4), 2577-2592

L. D. Hicks, M. S. Dresselhaus, Phys. Rev. B., 1993, 47, 12727-12731.

B. Poudel, Q. Hao, Y. Ma, Y. Lan, A. Minnich, B. Yu, X. Yan, D. Wang, A. Muto, D. Vashee, X. Chen, J. Liu, M. S. Dresselhaus, G. Chen, Z. Ren, Science, 2008, 320, 634-638

B. Rijal, A. Baimyrza, T. Parein, Q. Lonné, D. Blond, R. Retoux, F. Gascoin, L. Le Pluart, C. Lemouchi, Nano-Structures & Nano-Objects, 2021, 25, 100629

261 Y. Du, J. Xu, B. Paul, P. Eklund, Applied Materials Today, 2018, 12, 366-388

Q. Zhang, Y. Sun, W. Xu, D. Zhu, Adv. Mater., 2014, 26, 6829.

J.L. Blackburn, A.J. Ferguson, C. Cho, J.C. Grunlan, Adv. Mater., 2018, 30, 35.

Md. N. Hasan, H. Wahid, N. Nayan, M. S. Mohamed Ali, Int J Energy Res. 2020, 1-53

B. Lüssem, M. Riede, K. Leo, Phys. Status Solidi A, 2013, 210(1), 1-232

S. Kobayashi, T. Takenobu, S. Mori, A. Fujiwara, Y. Iwasa , Appl. Phys. Lett., 2003, 82(25), 4581

Y. Lu, Z-D. Yu, Y. Liu, Y-F. Ding, C-Y. Yang, Z-F. Yao, Z-Y. Wang, H-Y. You, X-F. Cheng, B. Tang, J-Y. Wang, J. Pei, J. Am. Chem. Soc., 2020, 142, 15340-15348

D. Fazzi, M. Caironi, C. Castiglioni, J. Am.Chem. Soc., 2011, 133, 19056-19059.

S. Wang, H. Sun, U. Ail, M. Vagin, P.O. Persson, J.W. Andreasen, W. Thiel, M. Berggren, X. Crispin, D. Fazzi, S. Fabiano, Adv. Mater., 2016, 28, 10764-10771.

Y. Wang, T. Hasegawa, H. Matsumoto, T. Mori, T. Michinobu, Adv. Funct. Mater., 2017, 27, 1604608

I. Osaka, K. Takimiya, Polymer, 2015, 59, A1-A15

Y-Q Zheng, Z-F Yao, J-H Dou, Y. Wang, W. Ma, L. Zou, S. Nikzad, Q-Y Li, Z-H Sun, Z-A Yu, W-B Zhang, J-Y Wang, J. Pei, Giant, 2021, 7, 100064

T. Lei, J-H. Dou, J. Pei, Adv. Mater., 2012, 24(48), 6457-6461

S. Fall, L. Biniek, Y. Odarchenko, D. V. Anokhin, G de Tournadre, P. Lévêque, N. Leclerc, D. A. Ivanov, O. Simonetti, L. Giraudet, T. Heisera, J. Mater. Chem. C, 2016,4, 286-294

V. Percec, M. Glodde, T.K. Bera, Y. Miura, I. Shiyanovskaya, K.D. Singer, V.S.K. Balagurusamy, P.A. Heiney, I. Schnell, A. Rapp, H.W. Spiess, S.D. Hudson, H. Duan, Nature, 2002, 419, 384-387.

B. Kang, R. Kim, S. B. Lee, S-K. Kwon, Y-H. Kim, K. Cho, J. Am. Chem. Soc., 2016, 138, 3679-3686

R.Kim, P. S. K. Amegadze, I. Kang, H-J. Yun, Y-Y. Noh, S.-K. Kwon, Y-H. Kim, Advanced Functional Materials, 2013, 23(46), 5719-5727

R. Ozdemir, D. Choi, M. Ozdemir, G. Kwon, H. Kim, U. Sen, C. Kim, H. Usta, J. Mater. Chem. C, 2017, 5, 2368-2379

G. Marineau-Plante, M. Nos, D. Gao, M. Durandetti, J. Hardouin, P-L Karsenti, C. Lemouchi, L. Le Pluart, G. D. Sharma, P. D. Harvey, ACS Appl. Polym. Mater., 2021, 3, 2, 1087-1096

Y. Xiao, D. Zeng, L. M. Mazur, A. Castiglione, E. Lacaze, B. Heinrich, B. Donnio, D. Kreher, A-J Attias, J-C Ribierre, F. Mathevet, Polymer Journal, 2017, 49, 31-39

V. Percec, M. Glodde, T.K. Bera, Y. Miura, I. Shiyanovskaya, K.D. Singer, V.S.K. Balagurusamy, P.A. Heiney, I. Schnell, A. Rapp, H.W. Spiess, S.D. Hudson, H. Duan, Nature, 2002, 419, 384-387.

N. I. Abdo, J. Ku, A. A. El-Shehawy, H-S. Shim, J-K. Min, A. A. El-Barbary, Y. H. Jang, J-S. Lee, J. Mater. Chem. A, 2013, 1, 10306-10317

D. Amsallem, A. Bedi, F. Tassinari, O. Gidron, Macromol., 2020, 53, 9521-9528

H. Trabelsi, F. Szönyi, S.Geribaldi, J. Fluor. Chem., 2001, 107, 177-181

W. Li, L. Yang, J. R. Tumbleston, L. Yan, H. Ade, W. You, Adv.Mater., 2014, 26, 4456-4462

C NMR (500 MHz, CDCl3) δ (ppm): 161.32,

142.02, 139.10, 137.41, 136.71, 133.81, 128.73,

C NMR (500 MHz, CDCl3) δ (ppm): 161.32,

144.88, 139.65, 139.03, 138.11, 136.23, 128.31,

C NMR (500 MHz, CDCl3) δ (ppm):

141.4, 99.8, 74.1, 65.7, 61.6.

H NMR (500 MHz, CDCl3) δ (ppm): 8.9ppm (broad peak),

Acknowledgments:

Undertaking this PhD has been a truly life-changing experience and it would not have been possible to be carried without the guidance and support that accompanied me during the journey from many people.

The synthesis of LA is prepared in six steps from 2-thiophenecarbonnitrile according to modified procedures as illustrated in scheme 3.

Scheme 3: The synthetic scheme of LA

In the literature, several procedures exist to synthesize the DPP core from a double condensation reaction between two 2-thiophene carbonitrile and bis ester derivative. The yields vary from 20 % to 90 %. 225,226,227 The procedure followed in the team is inspired by the work of J. M. J. Fréchet 228 with a yield of 54 %. The first step is the addition of excess of sodium to 2-methylbutanol for the formation of alcoholate. The next step is deprotonation of the ester to form enolate ion and its nucleophilic addition to the cyanide function. The same mechanism is repeated twice. The product 1 is isolated with a yield of 54 %.

The second reaction is the alkylation of lactam function. The linear alkyl chains are installed by nucleophilic substitution between deprotonated N of the lactam and halogenated chain in the presence of potassium carbonate and 18-crown-6 in DMF. Compound 2 is

Synthesis of branched alkyl chain:

The synthesis of the extended alkyl branched chain is already described in the literature. It is inspired by the work of Takimiya and al . in two steps from the brominated compound 19 using ethylene oxide 59 (Scheme 15).

Scheme 15: The synthesis alkyl branched chain with 3 carbon spacer 18

The first step through the preparation of the extended branched chain is the formation of brominated compound 19 from the alcohol starting material, which is commercially available. Two conditions were tested for bromination to obtain compound 19, the data of the reaction conditions are listed in table 12. The yield of the reaction was increased from 52 % to 90%. The next step in the preparation of extended branched chain is a nucleophilic addition of freshly prepared Grignard intermediate 20 from compound 19 to ethylene oxide to obtain alcohol with three carbon spacer 21. From reported procedure, 59,253 the compound 21 was obtained with a yield of 39 %. The next step is bromination reaction with bromine 59 to obtain the desired molecule 22 in a yield of 62 %.

The extended branched chain 22 was synthesized in small quantity. Therefore, it was tested in the functionalization of EDOT by applying a pre-functionalization strategy to attach Y= extended branched alkyl chain on (R)-EDOT-MeO-R-OP to prepare (R)-EDOT-MeO-R-OR'. The electrochemical properties of DG90b have been studied by cyclic voltammetry by Muriel Durandetti from COBRA laboratory, Rouen. The data are listed in table 16. The levels of HOMO and LUMO are calculated from onset oxidation and reduction potentials, respectively. DG90 has one of the lowest LUMO in the literature (-4.52 eV) with a narrow band gap (Eg ele c = 0.82 eV), hence, it is a promising candidate for n-OFET and n-OTE applications.

Scheme 31: The synthesis of intermediate 38

Several attempts have been tested with activation of (R)-EDOT-MeOH or perfluorinated alcohol. However, the desired product was not obtained. So, the precursor 38 of Synthon C3 was obtained with a better yield of 65 % following the route 2.

Otherwise, we have also tested the synthesis of an analog of synthon C3 (39) with the presence of an alkyl spacer, because we have decided to use the intermediate 23 developed in chapter 2 for DPP containing metallooligomers preparation (Scheme 16). Besides the addition of spacer separates the fluorinated terminal from the heterocyclic backbone, which leads to a higher degree of organization. 320 Hence, the presence of aliphatic spacer could help to enhance the charge mobility. Indeed, preserving the stereoregularity will allow better aggregation. 346

Synthesis of the polymer T1:

Despite efforts made to improve the reaction conditions, BDTD-1 33 was obtained in too limited quantity to allow the synthesis of all the targets, therefore we decided to focus on the synthesis of the reference target T1.

From preliminary results, (BDTD-2T-EDOT)n polymer (DG90) was synthesized with a Stille coupling reaction under a heating at 90 °C for 16 hours in toluene.

For the synthesis of T1, due to the limited quantities of the compound 33, we decided to directly carry out the Stille coupling reaction with microwave heating in order to increase the reactivity and decrease the reaction time based on reported examples for other conjugated polymers (Scheme 35). 347 We carried out the same coupling reaction but with microwave heating as higher activation process by microwave heating could help to increase average molar mass of the polymers (Mn). Because of a few quantities of 33, we have tested two conditions, the data are listed in table 20. For condition 1 (MQ187), the reaction was carried out in toluene like for DG90 and heated at 95°C for twice 30 min with 200 W as power. The reaction was monitored by TLC after 30 min until no more starting material. The second condition (MQ192) was carried out in chlorobenzene to increase the temperature to 120 °C for 1 hour 30 min with 150 W as power (For these conditions the temperature was set (it's the power required to reach the temperature set)).

Scheme 35: The synthesis of polymer T1

Characterization of T1

The average molar masses (Mn) were determined by GPC with UV-visible calibration based on polystyrene (PS) standards to confirm polymer formation. Figure 156 illustrates the superposition of chromatograms from DG90-CHCl3 referred to DG90a (Mn=14.6 Kg.mol -1 ), DG90-CB referred to DG90b (Mn= 23.8 Kg.mol -1 ) and T1 for the two microwave heating conditions (MQ187, MQ192). Concerning T1, the analyses show two types of polymers populations: long and short chain polymers with the presence of two peaks. In the first condition, we got two peaks of small difference in intensity, the first one corresponds to polymer with longer chains (Mn= 48.3 Kg.mol -1 , Đ= 2.79) that those of DG90b. However, for the second condition (MQ192), we got two peaks in big difference of their intensity, where the less intense one corresponds to a much higher average molar mass (Mn= 330 Kg.mol -1 , Đ= 4.4) than those of DG90b. For the two conditions retention time of the first peak is shorter than that of DG90bs one. So, T1 has a higher Mn than DG90b (colored arrow in figure 157). Conditions 1 (MQ187) has the advantage of having the higher proportion of long chain polymers, while condition 2 (MQ192) has the advantage to form the highest average molar mass polymer even if the long chain polymers proportion is smaller. This is a promising result. Hence, further modifications of the microwave conditions are required as using longer heating time or other solvents like m-xylene that is of higher boiling point, allowing us to use higher heating temperature with longer reaction time.

Supporting Information

Supporting Information

Thermogravimetric analysis (TGA) were conducted on Perkin Elmer TGA Pyris 1. The samples were measured into an aluminium pan and sealed before heating with rate of 10 °C/min under a nitrogen atmosphere Metallooligomer thin films preparation. The solution of the metallooligomers (5mg.ml - 1 ) in CH2Cl2 were spin-coated using LabSpin6/8 from SÜSS MicroTec on glass and quartz substrates at 3000 rpm for 100 seconds at 600 rpm.s -1 acceleration. The film thicknesses were determined using a KLA-Tencor D-120 stylus profilometer.

UV-Visible analysis in CH2Cl2 were performed using the Perkin-Elmer (Lambda 35) UV-Vis Spectrometer (250-900 nm) in transmission mode. The UV-vis spectra (200 -900 nm) of film coated on quartz substrates were recorded by a Cary 4000 spectrophotometer (Agilent Corporation) in transmission mode using the double-beam mode Photoemission analysis. UV-visible spectroscopy was performed on a Varian Cary 50 spectrophotometer for solutions and films at 298 K and on a Hewlett-Packard 8452A diode array spectrometer for solutions at 77 K. Steady-state measurements, emission and excitation spectra, were made using a Edinburgh Instruments FLS980 Phosphorimeter equipped with single monochromator. Solutions for 298 K measurements were prepared in a glovebox to avoid excited state quenching by O2 and sealed in an airtight 1 cm cell. Low temperature measurements were made in an NMR tube using a homemade sample holder. Films were made by spin-coating the polymers on 2.5 cm quartz discs. Measurements exceeding 800 nm were performed using a Photon Technology International QuantaMaster 400 phosphorimeter coupled with a NIR PMT-7-B detector. The fluorescence lifetime measurements were performed on the FLS980 using a 378 nm picosecond pulsed diode laser.

The electrochemical measurements were carried out using an BioLogic SP-300 apparatus, at room temperature, under an argon atmosphere, in a three-electrode cell containing anhydrous acetonitrile (MeCN, 10 mL) as solvent and tetrabutylammonium hexafluorophosphate (TBAPF6, 10 -1 mol.L -1 ) as supporting salt at a scan rate of 50 mV.s -1 . The reference electrode was a saturated Hg/Hg2Cl2 reference electrode (further noted SCE for Saturated Calomel Electrode) from Radiometer. It was separated from the cell solution by a bridge compartment filled with the same solvent / supporting electrolyte solution as used in the cell. The counter electrode was a platinum wire. The working electrode was a disk obtained from a cross-section of a platinum wire (d = 5 mm) sealed in Teflon. Metallooligomer thin films were cast from dichloromethane solution on a platinum disc working electrode (d = 5 mm), and the cyclic voltammograms were recorded in acetonitrile solution containing TBAPF6, 10 -1 mol.L -1 as supporting salt at a scan rate of 50 mV.s -1 .

Experimental part of chapter 2

Scheme S1: The synthetic route of metallooligomer LA

3,6-Bis(thiophen-2-yl)-2H,5H-pyrrolo[3,4-c]pyrrole-1,4-dione (1) 222

The procedure was inspired from the literature, C. H. Woo, P. M. Beaujuge, T. W. Holcombe, O. P. Lee, J. M. J. Fréchet, J. Am. Chem. Soc. 2010, 132, 15547. In a flame-dried 250 mL bicol, sodium metal (Na (0)) (2.4 g, 104.39 mmol) was slowly added to the 2-methylbutan-2-ol (100 mL) at 120°C. The mixture was stirred at 120 °C until complete dissolution of Na (0). Then the temperature was decreased to 90 °C and the 2-thiophenecarbonitrile (8.5 g, 78.10 mmol) was added in one portion, affording a brown coloration of the reaction mixture. Afterwards, a solution of diethyl succinate (6.2 g, 35. 48 Interfaces, 2015, 7, 15978. In a 100 mL round bottom flask wrapped with aluminium, 2 (735.0 mg, 1.33 mmol) was dissolved in methylene dichloride (50 mL) and Nbromosuccinimide (521.0 mg, 2.93 mmol) was added in a single portion. Then the mixture was stirred at room temperature for 7 hours, monitored in TLC (Rf=0.5 using CH2Cl2/pentane: 70/30). Afterwards, the product was precipitated after addition of methanol (50 mL) to the concentrated reaction mixture. The dark purple solid 3 (708.2 mg, 1.00 mmol, 90 % yield) was isolated after filtration, washed with cold methanol (2 × 200 mL) and dried under vacuum.

3,6-di([2,2'-bithiophen]-5-yl)-2,5-dinonyl-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (4)

The procedure was inspired from the literature, Y. Zou, D. Gendron, R. Neagu-Plesu, and M. Leclerc, Macromolecules, 2009, 42(17), 6361. In flamed-dried schlenk under argon atmosphere, 3 (170.4 mg, 0.240 mmol) was dissolved in 20 mL of anhydrous and degassed toluene, Pd(PPh3)2Cl2 (16.84 mg, 24.0 μmol, 10 mol%) and PPh3 (12.6 mg, 48.0 μmol, Rf(9) = 0.7). The reaction mixture was quenched with sodium thiosulfate aqueous solution and extracted with methylene chloride. The organic layer was washed with brine, dried over magnesium sulfate and filtered. The solvent was evaporated under reduced pressure. The crude product was purified by chromatography on silica gel with 100 % CH2Cl2 as eluent. The target product was isolated as dark purple solid (160 mg, 0.16 mmol, 89.7 % yield).

The resolution of 1 H NMR spectrum was poor; only main signals were detected, but the compound was characterized by mass spectrometry and was engaged in next step without further purification. The product 26' is issued from the same synthesis as the product 26.

HR-MS (ESI+

1,2-dimethylsulfide-2,5-bis(trimethylsillacetylene)benzene (29)

The procedure was inspired from the literature, Hideaki Ebata, Eigo Miyazaki, Tatsuya Yamamoto, and Kazuo Takimiya, Org.

Lett. 2007, 9, 22, 4499-4502. In 50mL Schlenk and under argon, 28 (1.5g, 3.5mmol, 1eq.) were added in diethylether (15 mL).

Then tert-Butyllithium 1.9 M in pentane (7.4 mL, 14.1 mmol, 4 eq.) were added at -78°C and stirred for 15 min at -78°C. Then the temperature was allowed to warm up to R.T gradually and dimethyldisulfide (0.62 mL, 7.0 mmol, 2 eq.) was added and the reaction medium was stirred for 15 min. The reaction was quenched with water and stirred for 1 hr. The mixture was extracted with chloroform. The organic layer was washed with NH4Cl aqueous solution and brine, then it was dried with MgSO4, filtered and evaporated evaporating under reduced pressure. The product was purified after its precipitaton in pentane/ethanol: 10 mL/ 10 mL and it was isolated as a green solid (1.07g, 84 %).

Applying the two routes requires the synthesis of the stannic thiophene functionalized with alkyl chain R1.

Scheme S7: The synthetic scheme of stannic thiophene TSn1 (Synthon B)

3-dodecylthiophene (TR1)

The procedure was inspired from the literature, Lanqi Huang, Guangjun Zhang, Kai Zhang, Qiang Peng, and Man Shing Wong, macromolecule, 2019, 52, 12, 4447-4457.

To Magnesium tunings (3.06g, 0.126mol) in a Schlenk flask under Argon, 40 ml diethyl ether were added and 1-bromododecane (7.98g, 0.032mol), followed by reflux for 3 hours under Argon. After cooling to room temp the mixture were transferred to a solution of 3bromothiophene (5 g, 0.0307mol), dichloro(1,3-bis(diphenylphosphino)propane)nickel(II) (57.7mg) in ether (10mL) at 0°C. after the reaction mixture was refluxed under Argon overnight. Then, the reaction mixture was poured into ice followed by extraction using diethyl ether and the organic layer was washed and dried over magnesium sulfate. After removing the solvent by evaporation, the crude product was purified by silica gel column chromatography and vacuum distillation, the product obtained as gel (74%) The reaction was monitored by TLC (eluent: pentane, Rf of compound before disylilation = 0.55). After cooling to room temperature, TBAF (12.75 mL, 1 M in THF, 12.75 mmol) was added, and the reaction mixture was stirred for 2 h at R.T. The reaction was monitored by TLC (eluent: pentane, Rf (31) = 0.3). The reaction mixture was extracted with pentane, the organic layer was washed with water and dried over magnesium sulfate and filtered. After evaporation of the solvent under reduced pressure, the crude product was purified by silica gel column chromatography (eluent: 100% pentane). The product 31 was isolated as a white powder (480 g, 0.69 mmol, yield = 71%). The next two intermediates prepared from 31 for the synthesis of 33 are not stable in deuterated solvents. Therefore, they are not well characterized in 13 C NMR and due to the poor resolution only the signals from aromatic part were presiced in 1 H NMR. However, their formation was evidenced by ESI with exact mass determination by Karine Jarsale at LCMT-ENSICAEN.

3,7-Bis[(4-dodecyl) thiophen-2-yl] benzo[1,2-b:4,5-b']dithiophene-2,6-dione (32)

The procedure was inspired from the literature, Kohsuke Kawabata, Masahiko Saito, Itaru Osaka, and Kazuo Takimiya, J. Am. Chem. Soc. 2016, 138, 772. The procedure was inspired from the literature, Kohsuke were added into Schlenk under Argon, then 4 mL of dry toluene were added. The reaction was carried using microwave for 30 min at 95°C under Argon. The reaction was monitored by TLC (eluent: pentane). After cooling to room temperature, the mixture was extracted with pentane, the organic layer was washed with water and dried over magnesium sulfate. After filtration and evaporation of the solvent by evaporation under reduced pressure, the crude product was purified on Biobead® X1 by Size Exclusion Chromatography by 100% CH2Cl2 to isolate polymer T1 as dark green product.

Abstract

This manuscript consists of two parts. The first part focuses on the development of new low band gap metallooligomers used as donors in organic heterojunction solar cells. They are prepared by a dehydrohalogenation reaction between a ligand L and trans-PtCl2(PBu3)2. They consist of the platinum metal with phosphine ligands and an organic part composed of donor (thiophenes) and acceptor (diketopyrrolopyrrole (DPP)). To reduce the electronic gap, the strategy used consists in modifying the structure of the ligand to increase the conjugation length, the planarity, the stabilization of the quinone form or to reinforce the "push-pull" effect in particular with the insertion of the 3,4-ethylenedioxythiophene (EDOT). This strategy allowed the preparation of new donors, which allowed to reach good performances with PCE of 14-15 % when they are associated with non-fullerene acceptors. In the second part, the objective is to synthesize new electro-deficient conjugated polymers to develop n-type organic field effect transistors (OFETs) with good air stability and high charge transport properties, these compounds can be doped to prepare n-type thermoelectrics (OTHEs). The targeted conjugated polymers should have properties such as: low band gap, high electron affinity and thus low LUMO level, good solubility, ambient stability, and good π-aggregation with an "edge-on" orientation of the chain stacking. The donor-acceptor strategy is applied to achieve a low band gap with benzo[1,2-b:4,5-b′]-dithiophene-2,6-dione (BDTD) unit as the acceptor associated with two alkyl chain functionalized thiophenes. Convergent synthesis, using three synthons, allows changing the type of chains on the aromatic units to reach the targeted properties, such as increasing solubility, stability, and molecular organization. A first polymer functionalized with linear alkyl chains was obtained. However, the lack of solubility and stability did not allow isolating and studying it. Thus, in perspective to this work, extended branched alkyl chains will be used to increase the solubility of intermediates and thus improve the synthesis and the purity of polymers.

Key words: conjugated polymers, metallooligomers, organic synthesis, organic thermoelectrics, organic solar cells, organic field effect transistors