Mickaël Mateos

Rita Meunier-Prest
email: rita.meunier-prest@u-bourgogne.fr

Jean-Moïse Suisse

Marcel Bouvet
email: marcel.bouvet@u-bourgogne.fr

Modulation of the organic heterojunction behavior, from electrografting to enhanced sensing properties

Keywords: molecular materials, organic electronics, diazonium salts, impedance spectroscopy, ammonia sensors

Introduction

In organic electronics, the performances of devices, light emitting diodes, photovoltaic cells and field-effect transistors (OFET) depend not only on the chemical nature, morphology and structure of the materials that compose them, but also on the interfaces. Thus, in OFET the semiconductor-dielectric material interface plays a key role, and in diodes the interface between the p-type and n-type materials as well. Different strategies were developed to modify the electrode-semiconductor interface, like using self-assembled monolayers (SAMs) of thiol derivatives on gold [START_REF] Kim | Large enhancement of hole injection in pentacene by modification of gold with conjugated self-assembled monolayers[END_REF][START_REF] Cheng | Controlling electron and hole charge injection in ambipolar organic field-effect transistors by self-assembled monolayers[END_REF][START_REF] Ulman | Formation and structure of self-assembled monolayers[END_REF][START_REF] Gooding | The molecular level modification of surfaces: from selfassembled monolayers to complex molecular assemblies[END_REF] or the grafting of organosilicon derivatives or phosphonic acids on oxides, via reactions with hydroxyl groups. [START_REF] Ulman | Formation and structure of self-assembled monolayers[END_REF][START_REF] Gooding | The molecular level modification of surfaces: from selfassembled monolayers to complex molecular assemblies[END_REF][START_REF] Hotchkiss | The modification of indium tin oxide with phosphonic acids: mechanism of binding, tuning of surface properties, and potential for use in organic electronic applications[END_REF][START_REF] Lange | Tuning the work function of polar zinc oxide surfaces using modified phosphonic acid selfassembled monolayers[END_REF][START_REF] Aghamohammadi | Threshold-voltage shifts in organic transistors due to self-assembled monolayers at the dielectric: evidence for electronic coupling and dipolar effects[END_REF] Besides, a particularly powerful method is the electrochemical reduction of diazonium salts [START_REF] Delamar | Covalent modification of carbon surfaces by grafting of functionalized aryl radicals produced from electrochemical reduction of diazonium salts[END_REF][START_REF] Santos | Formation of mixed organic layers by stepwise electrochemical reduction of diazonium compounds[END_REF] that leads to the electrografting of organic layers on conducting substrates, [START_REF] Bélanger | Electrografting: a powerful method for surface modification[END_REF] including ITO surfaces. [START_REF] Lo | The role of diazonium interface chemistry in the design of high performance polypyrrolecoated flexible ITO sensing electrodes[END_REF][START_REF] Maldonado | Surface modification of indium tin oxide via electrochemical reduction of aryldiazonium cations[END_REF][START_REF] Chen | A Molecule with Dual functionality 4-aminophenylmethylphosphonic acid: a comparison between layers formed on indium tin oxide by in situ generation of an aryl diazonium salt or by selfassembly of the phosphonic acid[END_REF][START_REF] Santos | Surface patterning based on nanosphere lithography and electroreduction of in situ generated diazonium cation[END_REF] Furthermore, we developed new heterojunctions that are not simply a p-n junction between two materials. Combining a low conductive material deposited on interdigitated electrodes with the lutetium bisphthalocyanine, LuPc2, as an intrinsic semiconductor, covering the first layer, we obtained a particular device called MSDI for molecular semiconductordoped insulator heterojunction, [START_REF] Bouvet | semiconductor-doped insulator (MSDI) heterojunctions: Oligothiophene/bisphtalocyanine (LuPc2) and perylene/bisphthalocyanine as new structures for gas sensing[END_REF][START_REF] Gaudillat | Bias and humidity effects on the ammonia sensing of perylene derivative/lutetium bisphthalocyanine MSDI heterojunctions[END_REF][START_REF] Parra | Molecular semiconductor-doped insulator (MSDI) heterojunctions: an alternative transducer for gas chemosensing[END_REF] and also double lateral heterojunctions. [START_REF] Mateos | Comprehensive study of poly(2,3,5,6-tetrafluoroaniline): from electrosynthesis to heterojunctions and ammonia sensing[END_REF] In the present work, we studied the effect of the electrochemical modification of the ITOsublayer interface on the response to ammonia of LuPc2 resistors and MSDI heterojunctions.

We grafted various benzene derivatives by electrochemical reduction of diazonium salts prepared from a series of aniline derivatives. The quality of the grafting was controlled using a redox probe and by electrochemical quartz crystal microbalance (EQCM). Then, the impact of this functionalization on the behavior of the LuPc2 resistor and the MSDI prepared from the perfluoro-copper phthalocyanine (CuF16Pc), as a n-type sublayer, associated with LuPc2, was studied by means of I(V) characteristics and impedance spectroscopy. We related the enhancement of the sensing properties, in particular the limit of detection (LOD), with the change in electrical behavior of the organic electronic devices caused by electrode surface modification.

Experimental Section

Chemicals: 4-Trifluoroethoxyaniline (TFEA), 2,5-dimethoxyaniline (DMA), 2,3,5,6tetrafluoroaniline (TFA), perchloric acid 70%, sodium nitrite NaNO2 were purchased from Sigma Aldrich and used as received. K3Fe(CN)6 and K4Fe(CN)6 were purchased from Arcos Organics and used as received. Absolute ethanol (analaR normapur) was purchased from Carlo Erba. Aniline (Aldrich) was distilled at 120°C under reduced pressure before use. All perchloric acid solutions were prepared by dilution from HClO4 70 %. Ammonia gas, at 985 and 98 ppm in synthetic air, and synthetic air were used from standard gas cylinders, purchased from Air Liquide, France. Lutetium bisphthalocyanine (LuPc2) and perfluorinated copper phthalocyanine (CuF16Pc) (Fig. S1) were synthesized according to previously described methods. [START_REF] Clarisse | Synthesis and characterization of some lanthanide phthalocyanines[END_REF][START_REF] Birchall | Polyfluoroarenes. Part XIV. Synthesis of halogenophthalocyanines[END_REF] Sample preparation: Grafting of the different molecules was performed as follows: a solution of NaNO2 0.1 M in water and a solution of the aniline derivative 2 mM in HClO4 1 M were deoxygenated for 15 min with Argon. Then, 40 µL of the first solution was introduced in 1 mL of the second one. The mixture is stirred in the dark, during 5 to 10 min. The deposition was driven by CV (between 25 and 40 cycles) from 0 to -0.65 V at 40 mV s -1 . The experiment was stopped after consumption of around 15 mC cm -2 and no more evolution of the voltammogram.

The modified electrode was rinsed with water, and dried under vacuum at room temperature. Cu(F16Pc), 40 nm in thickness, was deposited on IDEs, by sublimation under secondary vacuum (ca. 10 -6 mbar), in an UNIVEX 250 thermal evaporator (Oerlikon, Germany). The top layer, LuPc2, 50 nm in thickness, was deposited on the first layer, without breaking the vacuum between the two evaporation steps. LuPc2 resistors were also prepared with the same process and the same thickness (50 nm). All the evaporations were carried out at a rate of 1 Å s -1 , by heating in a temperature range of 400-500 °C.

Electrical and chemosensing measurements: All electrical and sensing measurements were performed at room temperature, using a 6517B Keithley electrometer equipped with an embedded DC voltage supply. The electrometer was controlled through a home-made software relying on a GPIB (IEEE488.2) bus connection for data communication. Current-voltage I(V) curves were registered between -10 and +10 V, while taking care to start and finish at 0 V bias.

Impedance data were obtained using a Solartron SI 1260 impedance analyzer. The frequency range was 10 Hz to 10 MHz with a fixed ac oscillation amplitude of 200 or 300 mV and a bias ranging from 0 V to 10 V. A commercial software Zview from Ametek was used for impedance data fitting and parameter extraction. The workbench used for NH3 exposure, at different relative humidity (rh) values, was described previously. [START_REF] Gaudillat | Bias and humidity effects on the ammonia sensing of perylene derivative/lutetium bisphthalocyanine MSDI heterojunctions[END_REF] The total flow was in the range 0.5-0.55 nccm depending on ammonia concentration and the volume of the test chamber was 8 cm 3 . Gas sensing experiments were carried out in a dynamic way, by alternating 4 min-long rest periods and 1 min-long exposure periods.

Results and discussion

Covalent grafting by reduction of diazonium salts

Because of the strongly fluorinated nature of the Cu(F16Pc) underlayer in the MSDIs, we first opted for depositing a fluorinated layer based on 2,3,5,6-tetrafluoroaniline (TFA) and 4trifluoroethoxyaniline (TFEA) in order to improve the affinity of the underlayer for the electrodes. For comparison, aniline (ANI) was used as a control and a derivative containing electron-donating groups, 2,5-dimethoxyaniline (DMA) as well. The diazoniums were generated in situ. The voltammograms of the various diazonium salts show a large irreversible reduction peak on the first scan, followed by a rapid collapse of the current over cycles, due to a progressive passivation of the electrode (Fig. 1). This behavior is typical of a covalent grafting after generation of radicals by the electroreduction of diazonium salts. [START_REF] Bélanger | Electrografting: a powerful method for surface modification[END_REF] After reduction of the diazonium function, the use of ANI, DMA, TFA and TFEA leads to the grafting of benzene (Bz), 1,4-dimethoxybenzene (DMBz), 1,2,4,5-tetrafluorobenzene (TFBz) and trifluroethoxybenzene (TFEBz), respectively.

Electrochemical characterizations

Electrochemical methods are detailed in supplementary materials (S2). Before using these modified IDEs to build devices, the quality of the grafting on ITO substrates was checked using a reversible electrochemical probe, the hexacyanoferrate (III) / (II) couple (Fig. S3). The blocking rate (ratio of the anodic peak current after and before grafting) exceeds 99% for the grafting of DMBz, TFBz and Bz, and 96% for TFEBz, showing a good coverage. In order to guarantee the robustness of the grafting, the stability of the signal was controlled after submitting the modified ITO electrode to ultrasounds for several minutes in water and then in ethanol.

The grafting of the various aniline derivatives was followed by coulometry and EQCM (Fig. 1c). The surface coverage was calculated by coulometry, Γq and by EQCM, ΓΔf (Table 1) (Eq. 1, 2):

Γ 𝑞 = 𝑞 𝑛 * 𝐴 * 𝐹 (1) Γ Δ𝑓 = -Δ𝑓 𝐾 * 𝑀 𝑖 (2)
with q (C) the consumed charge, F (C mol -1 ) the Faraday constant, A (cm 2 ) the active area of the electrode, n the number of electrons involved in the reaction, Δf (Hz) the frequency shift measured by EQCM, Mi (g mol -1 ) the molar mass of the grafted species and K (Hz cm 2 g -1 ) the calibration factor of the microbalance. The theoretical coverage for a close packed monolayer of benzene is around 5 10 -10 mol cm -2 . [START_REF] Kuo | Electrochemical Modification of Boron-Doped Chemical Vapor Deposited Diamond Surfaces with Covalently Bonded Monolayers[END_REF] This value was used to estimate the number of deposited layers, Nlayers.

ΓΔf was low for the fluorinated species, 6.9 and 1.2 10 -9 mol cm -2 , for TFBz and TFEBz, respectively, due to the high steric hindrance and strong hydrophobicity of the fluorine atoms of these two species that inhibit the radical polymerization mechanism responsible for the multilayer formation, whereas it was of the order of 3 10 -8 mol cm -2 for DMBz and Bz, because Bz and DMBz have positions more accessible for polymerization. The grafting tended to a monolayer for TFEBz while the number of layers increased to 60 for DMBz and Bz, evidence that a radical polymerization occurred. The fraction of charge that was actually used to grow film was less than 20% whatever the compound and even lower than 1% for the grafting of TFEBz. Thus, the EQCM allows a more reliable measurement of the surface coverage, which was assumed to be identical on IDE and ITO coated quartz.

Electrical characterizations of devices

LuPc2 resistor I(V) characteristics:

The I(V) characteristics of modified LuPc2 resistors revealed that the grafting of Bz and TFBz radically changed the behavior of resistors moving from an ohmic regime to a non-linear regime, with a threshold effect at low voltages (Fig. 2a). The threshold voltage, Uth, determined by extrapolating to zero current the tangent to the curve at high bias, provides an evaluation of the non-linear character of devices. The TFBz-modified resistor exhibited a Uth of 2.4 V, close to that of an n-MSDI, against 1.4 V with Bz, although the Bz film is thicker than that with TFBz. The fluorine atoms help to raise the energy barrier at the ITO -LuPc2 interface. The grafting of TFBz generated a greater threshold effect despite its lower thickness. Whereas LuPc2 makes ohmic contact with ITO, the grafting induced electron and hole injection barriers (Fig. S4) that explain the appearance of a threshold voltage.

Impedance spectroscopy: The Nyquist diagram of the resistor made on bare ITO revealed a single semicircle whose diameter decreased slightly from 1.58 MΩ to 1.45 MΩ when the bias went from 0 to 10 V (Fig. 2b). This Nyquist plot was modeled by an equivalent circuit consisting in a R1-CPE1 block that corresponds to the electrical properties of LuPc2 (conductivity and permittivity) in series with a resistance (R2) that corresponds to the metallic contact of the cell.

A CPE (Constant Phase Element) represents an imperfect capacitance, [START_REF] Hsu | Technical note: concerning the conversion of the constant phase element parameter Y0 into a capacitance[END_REF] its impedance ZCPE being defined as follow (Eq. 3):

𝑍 𝐶𝑃𝐸 = 1 𝑄(𝑗𝜔) 𝛼 (3)
with ω = 2πf, where f is the frequency, Q the non-ideal capacitance, and α a value between 0 and 1 that reflects the non-ideality of the capacitive element. [START_REF] Kim | Impedance spectroscopy on copper phthalocyanine diodes with surface-induced molecular orientation[END_REF] In order to compare the devices, the effective capacitance, Ceff , was calculated for each R-CPE element (Eq. 4) [START_REF] Hsu | Technical note: concerning the conversion of the constant phase element parameter Y0 into a capacitance[END_REF]:

𝐶 𝑒𝑓𝑓 = 𝑅 1 𝛼 -1 * 𝑄 1 𝛼 (4)
For the LuPc2 resistor, Ceff is 6 pF. The  value, very close to 1 (0.97), indicates an homogeneous behavior of the material. The surface modification changed the aspect of the Nyquist diagram, with the appearance of a second circle at low frequency (LF) (Fig. 2c) whose diameter varies significantly with the bias as encountered in n-MSDI. [START_REF] Bouvet | Revisiting the electronic properties of Molecular Semiconductor -Doped Insulator (MSDI) heterojunctions through impedance and chemosensing studies[END_REF] The modeling of the Nyquist diagram of the n-MSDI modified with Bz was based on an equivalent circuit comprising two R-CPE blocks.

The R1-CPE1 block, at high frequency (HF), exhibited stable parameters, with an average resistance R1 of 760 ± 30 kΩ, a mean coefficient α1 of 0.95 ± 0.01 and an effective capacitance Ceff 1 of 5.8 ± 0.1 pF close to that of the resistor without surface modification. The R2-CPE2 block had a totally different behavior, with a huge decreased of R2 from 2.3 MΩ to 66 kΩ between 0 and 10 V, α2 went from 0.83 to 0.65 and Ceff 2 varied from 11 to 3.5 nF between 0 and 10 V, i.e. a thousand times greater than Ceff 1, which indicates that the phenomenon related to the R2-CPE2 block takes place on a very thin layer. R2 became lower than R1 for a bias between 1 and 2 V, which was closed to the threshold voltage previously determined on the I(V) curve. The resistor modified with TFBz showed the same behavior, with R2 becoming lower than R1 for a bias of the order of 3 V. All these observations allowed us to conclude that the R2-CPE2 block models the energy barrier at the ITO-LuPc2 interface due to the surface modification.

n-MSDIs I(V) characteristics:

The influence of the surface modification of IDE on the electrical behavior of n-MSDI Cu(F16Pc) (40 nm) -LuPc2 (50 nm) was studied. On the normalized curves, the TFBz grafting involved a broadening of the plateau at low current compared to the non-modified n-MSDI (Fig. 3). On the contrary, the grafting of TFEBz and DMBz caused only a small increase in the non-linear character of the I(V) curve. The threshold voltage allowed a better comparison of the impact of the different graftings. The TFBz and Bz graftings resulted in a large increase of Uth, at 6.3 and 5.3 V (Fig. 3c), respectively, compared to 2.6 V for the ungrafted MSDI. On the contrary, the grafting of DMBz and TFEBz did not significantly increase the energy barrier (3.3 and 3.8 V, respectively). So, Uth increases in the order DMBz < Bz < TFBz. This is clearly related to the chemical nature of the grafted layer, namely the fluorinated benzene leads to the strongest effect, whereas the benzene bearing electron-donating groups (DMBz) leads to the lowest effect. TFEBz has a lower effect than Bz because of the very thin deposited layer The origin of this variation of the interfacial energy barrier is known to result from the modification of the electrode workfunction because of the formation of interface dipoles. [START_REF] Kim | Large enhancement of hole injection in pentacene by modification of gold with conjugated self-assembled monolayers[END_REF][START_REF] Aghamohammadi | Threshold-voltage shifts in organic transistors due to self-assembled monolayers at the dielectric: evidence for electronic coupling and dipolar effects[END_REF] Impedance spectroscopy: The n-MSDI Cu(F16Pc) (40 nm) -LuPc2 (50 nm) without surface modification exhibited two semicircles. The first at HF was almost independent of the bias and the second at LF underwent a decrease of its diameter when the bias increased (Fig. 4a), whereas the LF semicircle became lower than the HF semicircle above 3 V and eventually negligible at 10 V. The surface modification did not modify the overall shape of the diagram (Fig. 4b), but affected the relative size of the two semicircles. In the absence of grafting, the LF semicircle became smaller than the HF semicircle at a bias of 3 V, but this limit voltage shifted towards 5 V (Fig. 4b) with the grafting of DMBz and even exceeded 10 V with TFBz. For the latter, the increase in the diameter of the LF semicircle was extremely high at low bias. The study by impedance spectroscopy confirmed that the surface modification exalts the threshold effect of the devices by increasing the energy barriers.

As for the modified resistors, the device can be modeled by two R-CPE in series (Fig. 4b) as detailed in supplementary materials (Fig. S5).

The evolution (R2 -R1) / R1 provided an evaluation of the predominance of interface effects for the different modified n-MSDIs (Fig. 4c). Indeed, R2 modeled the charge transfer resistance of the interfaces whereas R1 is related to the conductivity of the different materials. It was clearly shown that the surface modification extended the preponderance of the effect of interfaces when R2 is greater than R1. For the non-grafted device, the ratio vanished between 3 and 4 V, whereas it was canceled between 5 and 7 V for n-MSDI with DMBz and beyond 10 V with TFBz. The impedance spectroscopy behavior of the n-MSDI with grafting of TFEBz and Bz was very near this of the devices modified by DMBz and TFBz, respectively.

Ammonia detection in a humid environment

LuPc2 resistor

The pristine LuPc2 resistor was a poor ammonia sensor with a very low current variation under ammonia and an important drift of the baseline (Fig. 5a). On the contrary, the resistor with a Bz grafting exhibited an excellent baseline stability and a clear decrease under NH3, in agreement with the p-type nature of LuPc2 in the air (Fig. 5b).

The sensor measurements were studied at various bias values, with an optimal response at 0.5 V, i.e. below the Uth value determined from the I(V) characteristics. Plotting the calibration curves in the range 10 -90 ppm emphasized the impact of the surface modification of ITO (Fig. S6). The relative response RR of the device is defined as (Eq. 5):

𝑅𝑅 (%) = 𝐼 𝑓 -𝐼 0 𝐼 0 * 100 ( 5
)
where If and I0 are the current at the end of the exposure phase (1 min) and of the recovery phase (4 min), respectively.

Grafting increased |𝑅𝑅| at 90 ppm NH3, from 0.9 % for the reference resistor to 8.5 % and 12.6 % for devices modified by TFBz and Bz, respectively. Thus, the surface modification provided a threshold effect that broke the ohmic regime of the LuPc2 resistor and gave it more interesting sensing properties, as soon as the chosen bias was below the threshold voltage.

n-MSDI Cu(F16Pc) -LuPc2 on modified ITO

Response to ammonia in a humid environment: For the DMBz-modified MSDI, a significant increase in the current was observed under NH3, in accordance with the n-type nature of the fluorinated phthalocyanine (Fig. 6). The baseline of the sensor remained generally stable at constant humidity. It decreased only from 61 to 47 nA (bias = 1 V) when the relative humidity (rh) decreased from 50 to 10 %. The shift of the baseline was greater between 70 and 50% rh because the time of preconditioning between these two moisture levels was higher than for the other transitions. Water and ammonia are electron-donating species that neutralize holes in the LuPc2 layer and in turn increase the density of negative minority carriers in this top layer. Thus, the response was determined by the minority charge carriers, as already reported in the particular case of ambipolar sensing molecular materials. [START_REF] Chen | The lower rather than higher density charge carrier determines the NH3-sensing nature and sensitivity of ambipolar organic semiconductors[END_REF] The relative response of the sensor to ammonia was little affected by the moisture content. For a concentration of 90 ppm, the RR value was between 120 and 147 % over the entire humidity range, while it was between 94 and 117% at 60 ppm and finally between 62 and 80% at 30 ppm. Actually, this result is remarkable if we keep in mind that 70% rh corresponds to about 1.68 x 10 4 ppm water at room temperature. The response of the sensor was also determined in the range 1 -9 ppm at a constant humidity of 50%. The current increased sharply by 22 nA at 9 ppm of ammonia against 2 nA at 1 ppm, with an excellent signal-to-noise ratio (Fig. 6b), which will lead to a sub-ppm detection limit, as hereafter detailed.

The grafting of DMBz induced important changes in the sensor response of n-MSDI. Thus, in all the NH3 range, RR of the DMBz-modified sensor was about twice this of the unmodified MSDI (Fig. 6c). S1 andS2). All the measurements were performed at 1 V.

On the contrary, TFBz grafting that led to a higher threshold voltage altered the ammonia detection of n-MSDI Cu(F16Pc) -LuPc2, with a very weak I0 value, namely 30 nA at 50% rh and 20 nA at 10% rh, in spite of a bias of 2 V, against 1 V for the DMBz-modified device. At low ammonia concentration, the sensor response at 1 ppm was hardly noticeable. This indicates that the energy barrier participates to the sensor performances but only up to a limit value.

Calibration curves: The DMBz-modified MSDI exhibited a sensitivity S, defined as the slope the curve RR=f([NH3]), of 0.98 % ppm -1 in the range 40-90 ppm NH3, but up to 3.0 % ppm -1 in the range 1 -9 ppm, i.e. twice this of the pristine MSDI. The sensor response followed the behavior of a Langmuir adsorption isotherm, characterized by a quasi linear regime at low concentration and a saturation of the response at high concentration (Fig. 6c, Table S2). This than 1 ppm. Taking into account I0 (70 nA) and the noise at 1 ppm (0.1 nA), this device revealed a LOD (Eq. 6) of 140 ppb.

𝐿𝑂𝐷 = 3𝑁 𝑆 * 𝐼 0 ( 6
)
where S is the sensitivity in the 1 -9 ppm range, I0 and N are the baseline current and the noise, determined at 1 ppm on the curve I(t).

The n-MSDI without surface modification, reported previously, had never been the subject of studies at low concentrations. Taking into account its sensitivity (1.52% ppm -1 , below 10 ppm NH3), its I0 (511 nA) and the noise at 1 ppm (0.7 nA), a LOD of 280 ppb was deduced.

Contrary to DMBz, the grafting of TFBz degraded the sensing performances of MSDI. Indeed, to 0.3 nA leading to a LOD of 2 ppm. The grafting of TFEBz modifies very weakly the sensing 9 ppm and a RR of 45% to 90 ppm. This behavior was similar to that of the sensor modified with Bz.

It appears that the sensitivity of n-MSDI depends on the energy barriers at the p-n heterojunction between LuPc2 and Cu(F16Pc) and at the electrodesublayer interface. Indeed, the sensing measurements were carried out with a bias value lower than the total energy barrier, i.e. at a voltage where the current was limited by this energy barrier. The RR of n-MSDIs decreased when the voltage was increased, a too strong bias abolishing the energy barrier effect.

Comparative overview

We summarized the relative response of the present devices, with modified and unmodified electrodes, to a given concentration of ammonia, their average sensitivity and their LOD, by comparing them with the literature (Table 2). The n-MSDI Cu(F16Pc) -LuPc2 with grafted DMBz is the best MSDI developed in the laboratory. [START_REF] Gaudillat | Bias and humidity effects on the ammonia sensing of perylene derivative/lutetium bisphthalocyanine MSDI heterojunctions[END_REF][START_REF] Wannebroucq | New n-type molecular semiconductor-doped insulator (MSDI) heterojunctions combining a triphenodioxazine (TPDO) and the lutetium bisphthalocyanine (LuPc2) for ammonia sensing[END_REF] Its sensitivity was of the same order of magnitude as the polymer-based devices [START_REF] Gaudillat | From the solution processing of hydrophilic molecules to polymer-phthalocyanine hybrid materials for ammonia sensing in high humidity atmospheres[END_REF][START_REF] Patois | Ammonia gas sensors based on polypyrrole films: Influence of electrodeposition parameters[END_REF][START_REF] Van Hieu | Thin film polypyrrole/SWCNTs nanocomposites-based NH3 sensor operated at room temperature[END_REF][START_REF] Jian | Gas-sensing characteristics of dielectrophoretically assembled composite film of oxygen plasma-treated SWCNTs and PEDOT/PSS polymer[END_REF][START_REF] Mateos | Low conductive electrodeposited poly(2,5-dimethoxyaniline) as a key material in a double lateral heterojunction, for sub-ppm ammonia sensing in humid atmosphere[END_REF] but lower than devices made from graphene [START_REF] Yavari | High sensitivity detection of NO2 and NH3 in air using chemical vapor deposition grown graphene[END_REF] for which desorption is obtained by heating at ca. 200°C, or from hybrid materials, e.g. those that contain carbon nanotubes and gold nanoparticles (AuNP). [START_REF] Chang | Preparation of gold/polyaniline/multiwall carbon nanotube nanocomposites and application in ammonia gas detection[END_REF] The grafted n-MSDI is not the most sensitive but has the great advantage of operating in a humid environment unlike the other reported devices. [START_REF] Xu | Selective detection of NH3 over NO in combustion exhausts by using Au and MoO3 doubly promoted WO3 element[END_REF][START_REF] Wang | Enhanced sensitivity and stability of room-temperature NH₃ sensors using core-shell CeO₂ nanoparticles@crosslinked PANI with p-n heterojunctions[END_REF] Indeed, humidity, because of its high concentration, is the main interfering gas for most of NH3 sensors. On the other hand, the excellent sensitivity of the devices based on tungsten oxide and molybdenum was obtained at very high operating temperature (450 °C), [START_REF] Xu | Selective detection of NH3 over NO in combustion exhausts by using Au and MoO3 doubly promoted WO3 element[END_REF] while the present organic devices have the advantage of operating at room temperature. Finally, the heterojunctions exhibit very good signal over noise ratios that lead to excellent LOD, comparable to the best LOD reported in the literature, [START_REF] Jian | Gas-sensing characteristics of dielectrophoretically assembled composite film of oxygen plasma-treated SWCNTs and PEDOT/PSS polymer[END_REF][START_REF] Chang | Preparation of gold/polyaniline/multiwall carbon nanotube nanocomposites and application in ammonia gas detection[END_REF] and even better for the DMBz modified MSDI.

Conclusion

Functionalization of ITO was carried out by reduction of four diazonium salts in aqueous medium. Although the blocking rate of a redox probe remained very good in all cases, the EQCM measurements revealed that the trifluoroethoxy group in the para position led to a very thin film, near a monolayer, the formation of about ten monolayers for the grafting of TFBz and up to several tens of monolayers for the grafting of Bz and DMBz.

In the case of LuPc2 resistors, the surface modification induced the ITO-LuPc2 interface did not form anymore an ohmic contact and the I(V) characteristics became nonlinear. By impedance spectroscopy, grafting revealed a second semicircle at low frequency associated to interfacial effects. The n-MSDIs that display nonlinear I(V) characteristics saw their threshold voltage increase by the modification of the ITO-Cu(F16Pc) interface. It highlights that the detection capacity of n-MSDI was due to the energy barrier coming from the p-n heterojunction and from the interface between the electrodes and the sublayer. The interaction between NH3 molecules and LuPc2 modifies the density of majority charge carriers and therefore indirectly the depletion zone that limits the current through the device. About ammonia detection, the surface modification significantly increased the relative response of LuPc2 resistors that went from 0.9 % at 90 ppm to 12 %, after grafting of benzene. In the case of n-MSDI, the results were more contrasted; with DMBz, the sensitivity of the device was doubled, from 1.5 to 3 it decreased for the other graftings. These experiments provided for the first time the LODs of n-MSDI, reaching 140 ppb for the most efficient one. It is worth noting that all the studies were achieved at room temperature in a humid environment. This work paves the way for the use of such conductometric sensors not only in the field of air quality monitoring but also in the field of health diagnosis by measurement in human breath. It also highlights the possibility of improving the performance of existing sensors by electrochemical modifications of electrodes, whatever the sensing material used. * non-linear but measured down to 0.5 ppm; ** measured at 25°C but desorption was achieved by heating under vacuum at ca. 200°C

Figure 1 .

 1 Figure 1. CV on IDE of a) DMA and TFA and b) TFEA and ANI at 2 mM + NaNO2 4 mM in HClO4 1 M; v = 40 mV s -1 ; c) monitoring of the consumed charge and the variation of frequency in EQCM, in solutions of TFEA, ANI, DMA and TFA.

Figure 2 .

 2 Figure 2. a) Current-voltage characteristics standardized by maximum current at + 10 V of an unmodified LuPc2 resistor on an unmodified (pink) and on TFBz-modified (blue) and Bzmodified (black) IDEs; Nyquist diagram according to the bias of LuPc2 resistors, b) without surface modification, c) with grafting of Bz on the surface of the IDE. Frequency 10 Hz -10 MHz, UAC = 200 mV.

Figure 3 .

 3 Figure 3. a) Current-voltage characteristics normalized by the maximum current at + 10 V of a n-MSDI Cu(F16Pc) -LuPc2 on TFBz -modified IDEs (red) and on unmodified IDEs (black); b) schematic view of the heterojunctions, the arrows indicate the main channel for charge carrriers; and c) threshold voltage of different n-MSDIs, depending on the nature of the performed grafting.

Figure 4 .

 4 Figure 4. Nyquist diagram at different bias values of n-MSDI Cu(F16Pc) (40 nm) -LuPc2 (50 nm), a) on unmodified IDE; b) with grafting of DMBz, with low impedance zoom and equivalent circuit in inserts; c) comparison of the threshold effect of modified n-MSDIs through the evolution of (R2 -R1) / R1 as a function of the bias. The pink (bare ITO) and red (ITO / DMBz) curves are linked with the left Oy axis and the green curve (ITO / TFBz) with the right Oy axis, respectively. Frequency 10 Hz -10 MHz, UAC = 300 mV.

Figure 5 .

 5 Figure 5. Current response through NH3 exposure / recovery cycles of 1 min / 4 min, at 50% relative humidity, of a LuPc2 resistor prepared: a) on bare ITO, b) on ITO with grafting of benzene; c) schematic view of the modified resistor. Polarization of 1 V for the bare ITO and 0.5 V for the ITO/Bz curve.

Figure 6 .

 6 Figure 6. a) Current response of a Cu(F16Pc) -LuPc2 n-MSDI modified with DMBz, upon exposure to ammonia via exposure / recovery cycles of 1 min / 4 min, at different rh values. An additional 1500 s conditioning period between 70 and 50 % rh was not presented; b) response of the same sensor at low concentrations of ammonia (1-9 ppm) and at a constant rh value (50 %); c) relative responses RR of the different n-MSDIs in the range 1 -90 ppm of ammonia, at 50% rh, with the Langmuir fittings and the sensitivity determination by linear regression in the range 1 -9 ppm (modeling parameters in TableS1 and S2). All the measurements were performed at 1 V.

Table 1 .

 1 Determination of the surface coverages of the different graftings carried out on quartz covered with ITO, calculated from coulometric and EQCM results.

		DMBz Bz TFBz TFEBz
	q/A [mC cm -2 ]	10.4	19.6 18.3	10.4
	-f [Hz]	520	280	133	28.3
	q [nmol cm -2 ]	200	175	186	106
	f [nmol cm -2 ]	25	28	6.9	1.2
	Nlayers	60	56	14	2

Table 2 .

 2 Summary of the sensing properties (RR, S, LOD) of the present devices compared to the literature.

	Devices	RR [%]	[NH3] [ppm]	S [% ppm -1 ]	LOD [ppb]	[NH3] [ppm]	T [°C]	rh [%]	Ref.
	F16CuPc -LuPc2 MSDI on bare ITO	67	90	1.5	280	1 -9	25	50	This work
	F16CuPc -LuPc2 MSDI on DMBz / ITO	138	90	3	140	1 -9	25	50	This work
	F16CuPc -LuPc2 MSDI on TFBz / ITO	50	90	1.1	2000	1 -9	25	50	This work
	F16CuPc -LuPc2 MSDI on TFEBz / ITO	45	90	1.3		1 -9	25	50	This work
	PTCDI -LuPc2 MSDI	34	90	0.6		10 -30	25	50	[16]
	TPDO -Lu Pc2 MSDI	26	90	0.2		30 -90	25	50	[26]
	PTFA -LuPc2 heterojunction	14	90	1.05	450	1 -6	25	50	[18]
	PDMA -LuPc2 heterojunction	14	90	2.23	314	1 -6	25	50	[31]
	PANI-CuTsPc resistor	78	30	1.9		10 -30	25	50	[27]
	PPy resistor	16	40	0.2	1000	40-75	25		[28]
	PPy -SWCNT resistor	26	10	0.5		140 10 -			[29]
	PEDOT/PSS-SWCNT resistor	33	300	0.21	200	100 2 -			[30]
	AuNP-PANI-MWCNT resistor	64	25	6	200	1 -10			[33]
	CVD synthesized graphene resistor	40	40	6 -0.09*	≈ 500	0.5 -1000*	25**		[32]
	MoO3-WO3 resistor	1000	5	200		5			[34]
	CeO2 -PANI resistor	550	50	11		2 -50			[35]

Acknowledgements

The authors acknowledge the Agence Nationale de la Recherche for funding through the ANR project OUTSMART ANR-2015-CE39-0004-03 and the MENESR for a PhD grant (M.

M.). Financial support from the European Union (FEDER) and the Conseil Régional de

Bourgogne through the FABER and the PARI SMT 08 and CDEA programs is gratefully acknowledged. We also acknowledge the Conseil Régional de Bourgogne through the CPER program.


Samer Chehade
email: samer.chehade@datahertz.fr

Nada Matta
email: nada.matta@utt.fr

Jean-Baptiste Pothin
email: jean-baptiste.pothin@datahertz.fr

Remi Cogranne
email: remi.cogranne@utt.fr

Data Interpretation Support in Rescue Operations: Application for French Firefighters

Keywords: Application Ontology, Data Interpretation, Firefighters, Knowledge Engineering, Knowledge Representation, Rescue of people

This work aims at developing a system that supports French firefighters in data interpretation during rescue operations. An application ontology is proposed based on existing crisis management ones and operational expertise collection. After that, a knowledge-based system will be developed and integrated in firefighters' environment. Our first studies are shown in this paper.

I. INTRODUCTION

Rescue of people consists in saving their life in case of distress situations by applying responsive operations. In France, it is defined as specific tasks to be accomplished by public services in order to ensure the safety of patients and victims by making them able to escape from dangers, securing intervention sites, providing medical help, and finally, ensuring the evacuation to an appropriate place of reception [START_REF]Comité quadripartie associant les représentants des structures de médecine d'urgence et des services d'incendie et de secours, la DDSC et la DHOS[END_REF]. These services have to deal with several flows of information coming from different sources. They have to make a decision based mainly on these data. Semantic representation techniques [START_REF] Studer | Knowledge engineering: Principles and methods[END_REF] [3] can be very helpful for them in order to make the right decision at the right moment. In this paper, we propose to build a dedicated ontology to represent French firefighters' activity as well as information and data flow in rescue operations. This paper is divided in three sections:

1. Definition of terms used in rescue operations and an illustration of data flow complexity 2. Semantic representation of data and information and related existing ontologies 3. ResOnt, the ontology we defined to help French firefighters

II. RESCUE OF PEOPLE IN DISTRESS

A. Definitions

Rescue of people, also named emergency rescue of people is one mission of firefighters and medical units. It consists in ensuring the safety of patients or victims by making them able to escape from a danger, securing sites on interventions, practicing first aid gestures, and, finally, ensuring the evacuation to a suitable place of reception.

In France, two public services are engaged in rescue operations and emergency care to the population: Departmental Fire and Rescue Service (SDIS) and Emergency Medical Assistance Services (SAMU) [START_REF]avril 2009 relatif à la mise en oeuvre du référentiel portant sur l'organi sation du secours à personne et de l'aide médicale urgente[END_REF]. SAMU are responsible of ensuring medical assistance while SDIS have a lot of tasks and missions including medical care in some cases. these two services have to cooperate and each one should be aware of the tasks and mission ensured by the other. In order to delimit missions and make responsibilities more clear, a common referential has been elaborated [START_REF]Comité quadripartie associant les représentants des structures de médecine d'urgence et des services d'incendie et de secours, la DDSC et la DHOS[END_REF]. This referential focuses on the sharing of responsibilities as well as making distinctions between duties of each service involved in rescue operations [START_REF]Comité quadripartie associant les représentants des structures de médecine d'urgence et des services d'incendie et de secours, la DDSC et la DHOS[END_REF]. The mission of SAMU is limited in [START_REF]Comité quadripartie associant les représentants des structures de médecine d'urgence et des services d'incendie et de secours, la DDSC et la DHOS[END_REF] to providing medical help in emergency situations. This task can be divided into the following five subtasks: 1) Provide permanent medical listening, 2) determine and trigger best responses to the nature of the calls, 3) ensure the availability of the means of hospitalization adapted to the patient's or victim's condition, 4) organize the transportation of the victim using a public service or a private health transport company and, 5) ensure the patient's admission [START_REF]Comité quadripartie associant les représentants des structures de médecine d'urgence et des services d'incendie et de secours, la DDSC et la DHOS[END_REF]. Whereas the mission of SDIS is to prevent, protect and fight fires [START_REF]Comité quadripartie associant les représentants des structures de médecine d'urgence et des services d'incendie et de secours, la DDSC et la DHOS[END_REF]. They are also responsible of other missions, in particular the rescue of patients or victims of accidents or disasters as well as their evacuation [START_REF]Article L1424-2 Code général des collectivités territoriales Modifié par Loi n°96-369 du 3 mai 1996 -JORF[END_REF]. Some other services and centers participate indirectly in rescue operations and emergency responses. These services and centers are connected to the two previous ones and are responsible of receiving calls, transferring calls to the good actor as well as ensuring a good communication and information exchange between SAMU and SDIS during and after a rescue operation. Each SDIS has a fire and rescue departmental operational center (CODIS) responsible for coordinating the operational activity of fire and rescue services at the departmental level. In addition, it has one or, if necessary, several alert processing centers (CTA), responsible for receiving, processing and possibly reorienting relief requests. Moreover, it possesses health and medical rescue service that participates, in particular, in emergency relief missions (SSSM) [START_REF]Comité quadripartie associant les représentants des structures de médecine d'urgence et des services d'incendie et de secours, la DDSC et la DHOS[END_REF]. On the other hand, each SAMU is connected to the Center of Receiving and Regulating Calls (CRRA) responsible of receiving calls and transferring them to the CTA of SDIS when the case imposes the participation of this latter in a rescue operation. They are also connected to Mobile Service of Emergency and Reanimation (SMUR) that provides care for a patient whose condition requires, urgently, medical care and resuscitation.

B. Information flow and complexity

Different rescue services, whose common objective is to sa ve lives, handle different tasks of the job. It is therefore critical for them to cooperate, communicate and coordinate. Add to that, information related to operations process and victim's status should be shared between actors as soon as possible. Information is the most important resource for coping and recovery work in rescue operations. It is the foundation for coordination and decision-making in best delays. Information take several forms such as text, audio and video. An example of information to be shared during a rescue operation is rescue record done by firefighters on the ground and sent to SAMU in order to prepare for the most suitable medical response to the victim. In order to ensure a good communication and sharing of information, [START_REF]Comité quadripartie associant les représentants des structures de médecine d'urgence et des services d'incendie et de secours, la DDSC et la DHOS[END_REF] imposes the interoperability between CRRA and CTA. The interconnection requirements are of two kinds: the first one is for audio communications (through public telephone lines and radio communications systems). The second one is for data through ANTARES network (National Adaptation of Risk and Rescue Transmissions). Due to the complexity and diversity of information, rescue actors usually have a problem to identify critical events to deal with at the right time in order to reduce consequences of urgent state. These actors have to make critical decisions in a very short lapse of time; each second can be important.

The objective of this work is to use semantic representation techniques in order to help rescue actors to understand more quickly critical events. From this point, we propose a new application ontology for rescue operations that will help in automating data processing and saving a lot of time.

C. Related work

During the last years, emergency responses and rescue operations have merged technologies of communication, computer, artificial intelligence, knowledge engineering and system engineering. Several systems and applications have been developed over the last ten years in order to help decision makers to ensure quick responses in these operations such as ISyCri [START_REF] Bénaben | A metamodel and its ontology to guide crisis characterization and its collaborative management[END_REF], SHARE [START_REF] Konstantopoulos | SHARE-ODS: An ontology data service for search and rescue operations[END_REF][8], RESCUER [START_REF] Villela | A smart and reliable crowdsourcing solution for emergency and crisis management[END_REF], DISASTER [10] [11], PIECES [START_REF] Kilgore | A precision information environment (PIE) for emergency responders: Providing collaborative manipulation, role-tailored visualization, and integrated access to heterogeneous data[END_REF]. These systems aim to provide rescuers with mobile technologies and services to support information management multimodal communications, interoperability of actors collaborative processes. More recent systems are oriented to decisionmaking in crisis situations, for example, Crisis Clever system [START_REF] Sediri | Crisis Clever , a System for Supporting Crisis Managers[END_REF], Decision support system for emergencies [START_REF] Zografos | A decision support system for integrated hazardous materials routing and emergency response decisions[END_REF] and systems that focus on information flow and data processing during disasters such as S 2 D 2 S [START_REF] Genc | Agent-based information infrastructure for disaster management[END_REF].

As mentioned above, our aim in this paper is to build an ontology to support firefighters in data interpretation during and after a rescue operation. Gruber defined ontology as "an explicit specification of conceptualization" [START_REF] Gruber | A translation approach to portable ontology specifications[END_REF]. Bachimont, declared that defining an ontology for a given domain and problem, is defining the relational and functional signature of a formal representation language and the related semantics [START_REF] Bachimont | Engagement Sémantique et Engagement Ontologique : Conception et Réalisation D'ontologies En Ingénierie Des Connaissances[END_REF]. Ontologies can be classified into three categories, each one having its own specifications and use cases [START_REF] Guarino | Formal Ontology and Information Systems[END_REF]. These categories depend on the level of generality of the ontology, and are separated into top-level ontologies, also called upper ontologies, domain ontologies, or application ontologies. Toplevel ontologies are independent of a specific domain or problem. They define general concepts such as action, event, time, object, matter, time, space and many others that can be used in several domains. Examples of these ontologies are SUMO (The Suggested Upper Merged Ontology) considered as the largest accessible ontology [START_REF] Pease | The Suggested Upper Merged Ontology: A Large Ontology for the Semantic Web and its Applications[END_REF], Sowa's Ontology represented in Sowa's diamond [START_REF] Jansen | Categories: the top-level ontology[END_REF], OpenCyc ontology [START_REF] Matuszek | An introduction to the syntax and content of Cyc[END_REF], DOLCE defined by its authors as an ontology of particulars [START_REF] Gangemi | Sweetening WORDNET with DOLCE[END_REF], and BFO developed by the Institute for Formal Ontology and Medical Information Science (IFOMIS) [START_REF] Grenon | Biodynamic ontology: Applying BFO in the biomedical domain[END_REF]. Domain ontologies are specification of top-level ontologies. They are related to a generic domain such as crisis management or rescue operations. Domain ontologies can also be specialized in order to build application ontologies that describe specific concepts in a particular domain and particular associated tasks. Good examples of domain ontologies are SOKNOS [START_REF] Liu | Ontologies for Crisis Management : A Review of State of the Art in Ontology Design and Usability[END_REF], ontologies related to crisis management and response domain [START_REF] Yu | Emergency ontology construction in emergency decision support system[END_REF] [START_REF] Xiang | Building a practical ontology for emergency response systems[END_REF] or ontologies for medicine and biomedical domains such as the Biodynamic Ontology which is a domain ontology based on the BFO upper ontology [START_REF] Grenon | Biodynamic ontology: Applying BFO in the biomedical domain[END_REF]. Moreover, many application ontologies have been built from which we cite EMERGEL ontology [START_REF] Azcona | DISASTER Data Interoperability Solution At Stakeholders Emergency Reaction 285069[END_REF], EDXL-RESCUER [START_REF] Barros | EDXL-RESCUER ontology: Conceptual model for semantic integration[END_REF] and SHARE-ODS [START_REF] Konstantopoulos | SHARE-ODS: An ontology data service for search and rescue operations[END_REF] developed to support DISASTER [START_REF] Azcona | DISASTER Data Interoperability Solution At Stakeholders Emergency Reaction 285069[END_REF] [START_REF] Frederik Schütte | Solving Interoperability Issues in Cross Border Emergency Operations[END_REF], RESCUER [START_REF] Villela | A smart and reliable crowdsourcing solution for emergency and crisis management[END_REF] and SHARE [START_REF] Konstantopoulos | SHARE-ODS: An ontology data service for search and rescue operations[END_REF] [8] projects respectively.

Our aim is to construct an application ontology related to rescue operations and to be more specific, to the organization, responsibilities, communications, processes and flow of information during a rescue operation ensured by firefighters in order to support them in data interpretation. However, aspects of coordination and cooperation are not covered in our ontology. During our literature review, we found several ontologies developed in the context of rescue operations. However, these ontologies are not publicly accessible and not directly applicable in our context such as SHARE-ODS [START_REF] Konstantopoulos | SHARE-ODS: An ontology data service for search and rescue operations[END_REF]. In addition, we also found several domain and application ontologies constructed in crisis and emergencies management domain to support decision makers. These ontologies can serve us to borrow ideas and some general concepts defined in these latter in order to construct our proper ontology specific for rescue operations ensured by French firefighters. However, they cannot be used completely in our case because a rescue response differs from crisis or emergency response in many concepts. In addition, some important concepts related to our context are not well defined in previous ontologies. For instance, actors organization and structures, dataflow, roles and many other concepts. From the ontologies that we found, we based our work on four ontologies that are the most suitable to our interests. These ontologies are EXDL-RESCUER [START_REF] Barros | EDXL-RESCUER ontology: Conceptual model for semantic integration[END_REF], EMERGEL [START_REF] Azcona | DISASTER Data Interoperability Solution At Stakeholders Emergency Reaction 285069[END_REF], the emergency ontology [START_REF] Yu | Emergency ontology construction in emergency decision support system[END_REF] and the emergency response ontology [START_REF] Xiang | Building a practical ontology for emergency response systems[END_REF]. Thus, we will give more details about these ontologies and the case of use of each one in section III.A. The advantage of our ontology is that it defines new concepts related to rescue operations, which are not defined in other ontologies.

III. SEMANTIC REPRESENTATION OF DATA

The complexity to process data coming from a variety of sources, and the lack of time during a rescue operation necessitate automation of information management procedures. Our goal is to define a methodology to help actors involved in rescue operations in data interpretation. Our methodology is based on semantic data recognition. It consists in using techniques and methods able to represent the human's expertise in a certain domain in order to simulate problem solving and data recognition. One of these techniques is Knowledge engineering, which enables modeling expertise's concepts [START_REF] Studer | Knowledge engineering: Principles and methods[END_REF]. This type of representation involves the construction of ontologies. Sowa defined knowledge representation as the use of ontologies and logic to build computable models in a domain [START_REF] Sowa | Knowledge representation: Logical, Philosophical, and Computational Foundations[END_REF]. Concepts can be represented at two levels: as a semantic network close to conceptual graphs defined by Sowa [START_REF] Sowa | Conceptual Graphs[END_REF] and in a computable way using logic languages [START_REF] Grimm | Knowledge representation and ontologies[END_REF]. Related to our purpose, several works have been distinguished in the context of knowledge engineering in order to build crisis and emergency response systems such as knowledge-based models proposed to support environmental emergency management [START_REF] Hernández | Knowledge-based models for emergency management systems[END_REF], or models to solve unconventional emergencies problems by using domain knowledge and ontologies [START_REF] Feng | Unconventional Emergencies Management Based on Domain Knowledge[END_REF].

A. Existing Ontologies

In this section, we give details about ontologies in order to adapt an ontology corresponding to firefighters rescue operations.

The first ontology chosen in this paper is a 'Domain Ontology' developed to support knowledge reorganization in decision support systems [START_REF] Yu | Emergency ontology construction in emergency decision support system[END_REF]. Authors constructed this ontology based on emergencies documentation by adopting the Activity First Methodology [START_REF] Mizoguchi | Ontology for Modeling the World from Problem Solving Perspectives[END_REF]. They defined four main classes: EVENT that can be a disaster or a disease, RESOURCE made of artificial and inartificial, SUBJECT divided into personal and actor, and TASKS consisting of "communication", "evaluation", "rescue", "prevention", and "detection". Each one of these classes is also divided into different subclasses, each having several instances. In the domain of rescue operations, this ontology can serve by giving the general concepts that are in common with crisis management. This ontology has the advantages to cover different contexts in emergency response, ranging from events to tasks, passing by subjects.

The second ontology we studied is the 'Task Ontology' that was constructed to support the implementation of the evacuation planning system for emergency cases and to standardize a group of semantic concepts used in different emergency systems [START_REF] Xiang | Building a practical ontology for emergency response systems[END_REF]. It defines a common vocabulary usable by emergency actors regardless of the emergency nature. To build this ontology, Xiang et al. identified four generic concepts that are Response Preparation, Emergency Response, Emergency Rescue, and Aftermath Handling. Each one of these concepts is divided into several sub concepts, illustrating the main steps and tasks to be taken in case of emergency. This ontology is restricted to the main missions to achieve during an emergency case from which we will take some concepts that are in common with rescue operations such as medical aid, communication and victim assistance.

The third ontology we consider is the EXDL-RESCUER ontology [START_REF] Barros | EDXL-RESCUER ontology: Conceptual model for semantic integration[END_REF] created to support the RESCUER project [START_REF] Villela | A smart and reliable crowdsourcing solution for emergency and crisis management[END_REF], which uses crowdsourcing information to assist actors in emergencies. This application ontology is based on Emergency Data Exchange Language and aims to construct a conceptual model correspondent to information exchange and coordination with other systems. It focuses on the type of exchanged information and it covers a group of message contexts in an emergency. In this ontology, authors defined twelve concepts related to the type of shared messages during an emergency response such as Alert, Info, ResponseType, MsgType, etc.

Finally, we studied the EMERGEL ontology [START_REF] Azcona | DISASTER Data Interoperability Solution At Stakeholders Emergency Reaction 285069[END_REF] constructed to support the DISASTER project [START_REF] Azcona | DISASTER Data Interoperability Solution At Stakeholders Emergency Reaction 285069[END_REF] [START_REF] Frederik Schütte | Solving Interoperability Issues in Cross Border Emergency Operations[END_REF], which focuses on Data-Interchange on a semantic level. This application ontology is constructed to temporally describe a crisis situation by defining different modules divided into transversal modules and vertical modules. In order to construct this ontology, authors chose to specify some toplevel classes defined in the generic ontology DOLCE [START_REF] Gangemi | Sweetening WORDNET with DOLCE[END_REF]. Transversal modules are time and space while vertical modules are objects representing concepts in real word, constructs representing a set of objects, and activities representing tasks to be achieved by objects and constructs. Each one of these modules is divided into many classes. For example, objects contains Person, Vehicle, Equipment, Infrastructure, SpatialPoint and Communication. This ontology is various and cover different subjects in disaster response.

We can note that in these ontologies different aspects are represented related to different goals of research: studying tasks, communication, operations, etc. In our work, we focus on data interpretation, so communication aspects are important in our work. However, communication concepts must be linked to tasks and means. We present in the following how these concepts can be combined in an application ontology.

B. ResOnt: Proposed Application Ontology

In this section, we discuss the "ResOnt" ontology we constructed to support data interpretation in rescue operations. To construct this ontology, we took several concepts defined in the studied ontologies detailed in III.A. Add to that, we analysed documents related to rescue operations in France [START_REF]Comité quadripartie associant les représentants des structures de médecine d'urgence et des services d'incendie et de secours, la DDSC et la DHOS[END_REF] [4] [START_REF]Article L1424-2 Code général des collectivités territoriales Modifié par Loi n°96-369 du 3 mai 1996 -JORF[END_REF], and we conducted an interview with an expert Firefighter in Aube's Department. Then we identified new concepts, we reorganized them with the existing ones extracted from the studied ontologies, we completed them and we built the rescue operations ontology. First of all, we Fig. 1. Hierarchy of Objects defined the rescue operation as a world and we divided it into two generic concepts OBJECTS and CONSTRUCTS as it has been done in EMERGEL [START_REF] Azcona | DISASTER Data Interoperability Solution At Stakeholders Emergency Reaction 285069[END_REF] ontology in order to make a first classification between different categories. These two categories represent endurants and perdurants defined in DOLCE [START_REF] Gangemi | Sweetening WORDNET with DOLCE[END_REF]. We chose to follow the classification of DOLCE [START_REF] Gangemi | Sweetening WORDNET with DOLCE[END_REF] since it provides concepts that can be the basis for interoperability between lower level ontologies and it is used in multilingual information retrieval and web-based systems and services.Objects are defined as a representation of concepts in the real world. In our ontology, the main category OBJECTS includes three main concepts that are Material, Person and Infrastructure and each one is divided into several sub-concepts as shown in Fig. 1. In Material, we consider all concepts and instances that are in relation with inartificial resources used during a rescue operation including vehicles, catering, safety, medical, technical equipment and for sure the equipment used to ensure communications. In persons we consider all people involved in a rescue operation. It is divided into two parts: victims who are the object of an operation and actors who are the subject of an operation. While infrastructure represents a site intervention that could be a road, a bridge or a building. On the other hand, Constructs represent concepts that are different from touchable objects. This category includes five main concepts that are Incident, Organization, Role, Tasks, and Data Flow divided each into many sub-concepts as shown in Fig. 2. Incident represents the type event behind the intervention. It can be a disease, a natural event causing victims, a fire or an accident.

Organizations represent the main organisms that participate in rescue operations in France and contains Red Cross, SDIS and SAMU connected each to different centers and services while Role represents the order of each person participating in an operation. Data Flow represents the exchanged information during, before and after an operation. It contains information about the weather, actors, the evolution of an operation and the situation during an operation. And finally, Tasks represents duties and missions needed to ensure a successful rescue operation. These tasks covers four main phases : 1) Preparation including all tasks to be taken before an operation in order to achieve any operation without wasting time, 2) Response including Coordination, Communication and Decision-Making, 3) Operation including tasks to be taken on the intervention site and, 4) tasks to be taken at the end of the operation such as reporting, investigation and social assistance of victims. However, due to a lack of space and the big number of concepts defined in tasks, we decided to represent them in a separated figure instead of putting them in the same figure of constructs as shown in Fig. 3.

The work done represents our first step in the implementation of the ontology. In this step, we defined concepts used in rescue operations and we made a first classification in a hierarchical tree. However, relations between these concepts have not been identified yet. Once done, we look forward implement, evaluate and submit it to an ontology catalog. In this paper, we presented the construction of an application ontology dedicated to French firefighters participating in rescue operations after studying several ontologies constructed in crisis management domain. This ontology will be the base of a system aiming to support firefighters in data interpretation. However, our ontology is not evaluated yet since it is our first study in this aim and the ontology is not implemented.

As a future work, we will detail this ontology and instantiate it based on expertise collection and modelling. Thus we will conduct series of interviews with firefighters operational staff involved in rescue operations. After that, we will implement our ontology in order to test it in real cases ,evaluate it and submit it to an ontology catalog. Finally, we will study the design and implementation of an information recognition system based on knowledge bases by exploiting the ResOnt ontology. This system will be integrated as a decision-support system in French firefighters working environment. This work includes naturally a study about the security and confidentiality of exchanged information.

Fig. 2 .

 2 Fig. 2. Hierarchy of Constructs