Julien Ramade

Junling Qu

Audrey Chu

Charlie Gréboval

Clément Livache

Nicolas Goubet

Bertille Martinez

Gregory Vincent

Emmanuel Lhuillier

Potential of Colloidal Quantum Dot based Solar Cell for Near-Infrared Active Detection

Keywords: PbS nanocrystals, near-infrared, photodetection, active imaging, long-distance imaging, time-gated detection

Nanocrystal-based solar cell technologies currently have two materials competing for the highest performances: PbS and perovskites. These latter benefit from a defect-tolerant electronic structure, while PbS benefits from a mature diode fabrication technique and from its near-infrared absorption. Here we choose to revisit the potential of these PbS photodiodes for near-infrared detection and more precisely for active imaging. This mode of detection combines an eye invisible source with a detector. Such detection mode is used for surveillance, industrial sorting, LIDAR, etc. Here we use a state-of-the-art photodiode geometry and we reveal its potential for near-IR active detection at 940 nm. The diode can achieve a high photoresponse of 0.5 A.W -1 , corresponding to an external quantum efficiency of 66% and a detectivity above 10 12 Jones at room temperature. The time response which is often neglected for solar cells is found to be 10 ns for rise time and 1 µs for decay time. We demonstrate that long-distance (over 150 m) and time-gated active imaging can be conducted using this device.

Spectral tunability of nanocrystals allow to cover a large range of the electromagnetic spectrum from UV to THz. [START_REF] Chen | Nanostructured Photodetectors: From Ultraviolet to Terahertz[END_REF][START_REF] Goubet | Terahertz HgTe Nanocrystals: Beyond Confinement[END_REF] Their ability to emit light have led to their integration into display, but their absorption feature appears to be even more robust (less sensitive to surface chemistry and oxidation). However, to really take advantage of absorption of nanocrystal film, the film also needs to be conductive which has required the development of ligand exchange methods. Native long capping ligands are typically replaced by shorter molecules which reduce the inter-nanoparticle tunnel barrier and raises the carrier effective mobility. Once such processes have been developed, photoconduction especially in the nearinfrared (NIR) have been investigated with in mind the design of solar cell which harvest the near IR part of the solar spectrum. [START_REF] Sargent | Infrared Quantum Dots[END_REF] Early device geometry was relying on a planar transport between interdigitated electrodes. Such photoconductive device has led to large responsivity [START_REF] Konstantatos | Ultrasensitive Solution-Cast Quantum Dot Photodetectors[END_REF] (up to 100 A/W) value thanks to photoconductive gain. [START_REF] Konstantatos | Colloidal Quantum Dot Photoconductive Photodetectors: Transport, Traps, and Gain[END_REF] Later the device signal to noise ratio was improved by switching to photovoltaic configuration. [START_REF] Luther | Stability Assessment on a 3% Bilayer PbS/ZnO Quantum Dot Heterojunction Solar Cell[END_REF][START_REF] Mcdonald | Solution-Processed PbS Quantum Dot Infrared Photodetectors and Photovoltaics[END_REF][START_REF] Luther | Schottky Solar Cells Based on Colloidal Nanocrystal Films[END_REF][START_REF] Semonin | Peak External Photocurrent Quantum Efficiency Exceeding 100% via MEG in a Quantum Dot Solar Cell[END_REF] They were initially based on Schottky contacts. [START_REF] Luther | Stability Assessment on a 3% Bilayer PbS/ZnO Quantum Dot Heterojunction Solar Cell[END_REF] Later the stack of layers have been improved to realize a pn junction. To date, current best devices are inspired by the structure proposed by Chuang et al, relying on a p-n junction obtained by stacking nanocrystal layers with two types of ligands: [START_REF] Chuang | Improved Performance and Stability in Quantum Dot Solar Cells through Band Alignment Engineering[END_REF] an halide [START_REF] Tang | Colloidal-Quantum-Dot Photovoltaics Using Atomic-Ligand Passivation[END_REF] and a short thiol. Even though this technology is currently challenged by perovskite quantum dots [START_REF] Protesescu | Nanocrystals of Cesium Lead Halide Perovskites (CsPbX3 , X = Cl, Br, and I): Novel Optoelectronic Materials Showing Bright Emission with Wide Color Gamut[END_REF] achieving impressive power conversion [START_REF] Sanehira | Enhanced Mobility CsPbI3 Quantum Dot Arrays for Record-Efficiency, High-Voltage Photovoltaic Cells[END_REF][START_REF] Swarnkar | Quantum Dot-Induced Phase Stabilization of Alpha-CsPbI3 Perovskite for High-Efficiency Photovoltaics[END_REF] (up to 13%) thanks to their defect-tolerant electronic structure, the external quantum efficiency of PbS solar cells can reach 50% and even more at the band edge. [START_REF] Bederak | Comparing Halide Ligands in PbS Colloidal Quantum Dots for Field-Effect Transistors and Solar Cells[END_REF][START_REF] Lu | High-Efficiency PbS Quantum-Dot Solar Cells with Greatly Simplified Fabrication Processing via "Solvent-Curing[END_REF] This advantage of perovskite materials is nevertheless currently limited to visible wavelengths because of the "wide" band gap nature of these materials. Consequently, PbS technology remains, by far, the most mature in the NIR. [START_REF] Hafiz | Colloidal Quantum Dots for Thermal Infrared Sensing and Imaging[END_REF][START_REF] Lhuillier | Recent Progresses in Mid Infrared Nanocrystal Optoelectronics[END_REF][START_REF] Livache | Road Map for Nanocrystal Based Infrared Photodetectors[END_REF][START_REF] Lu | Infrared Quantum Dots: Progress, Challenges, and Opportunities[END_REF] The PbS technology limitation for solar cells results from the large amount of trap states within the band gap which dramatically affects the open-circuit voltage. [START_REF] Jean | Radiative Efficiency Limit with Band Tailing Exceeds 30% for Quantum Dot Solar Cells[END_REF][START_REF] Chuang | Open-Circuit Voltage Deficit, Radiative Sub-Bandgap States, and Prospects in Quantum Dot Solar Cells[END_REF] On the other hand, the short circuit current in PbS photodiode can be pretty large (several tens of mA.cm -2 ) and thus similar to the best solar cells. [START_REF] Bi | Infrared Solution-Processed Quantum Dot Solar Cells Reaching External Quantum Efficiency of 80% at 1.35 Mu m and JSc in Excess of 34 mA cm -2[END_REF] Hence, the optimized solar cell geometry has a strong potential for near-IR sensing. Infrared sensing was one of the first targeted applications for PbS quantum dots devices, [START_REF] Konstantatos | Ultrasensitive Solution-Cast Quantum Dot Photodetectors[END_REF][START_REF] Rauch | Imaging with Quantum-Dot-Sensitized Organic Photodiodes[END_REF] however at that time, the maturity of PbS photodiodes was far weaker. Here we want to test the potential of this PbS nanocrystal-based solar cell structure for NIRactive imaging. In this application, an infrared source is used to illuminate a scene and the scattered light is collected. Active imaging finds applications for surveillance or industrial imaging for material sorting. Even though these types of applications are not the most demanding in term of External Quantum Efficiency (EQE) and dark current requirements, the range of photon flux can be several orders of magnitude weaker that the one considered for solar cell applications. Indeed, when for solar cells the only relevant Figure of Merit is the power conversion, new parameters become important for active imaging such as the signal-tonoise ratio and the time response.

The NIR range is an eye-blind region, where non-visible light emitting diodes (LEDs) and laser diodes can be used to illuminate a scene and be coupled with an InGaAs detector to build an active imaging setup. At 940 nm, the response of a silicon-based detector already starts to drop and using an InGaAs sensor leads to a dramatic increase of the cost compared to Complementary Metal Oxide Semiconductor technologies (CMOS). Development of low-cost alternatives to InGaAs is thus desirable, especially for applications where the high performance of InGaAs (EQE around 80% and dark current density down to a few nA.cm -2 ) is not required. It thus appears more realistic to use nanocrystal-based technology for applications where the level of dark current is not critical (i.e. scene with a reasonable amount of photons). Active imaging, and its derivative for industrial vision and LIDAR, fall in this kind of applications.

Here, we explore the use of a PbS quantum dot solar cell as a low-cost alternative to InGaAs for infrared active imaging. [START_REF] Georgitzikis | Integration of PbS Quantum Dot Photodiodes on Silicon for NIR Imaging[END_REF][START_REF] Georgitzikis | Optimization of Charge Carrier Extraction in Colloidal Quantum Dots Short-Wave Infrared Photodiodes through Optical Engineering[END_REF] We choose to target detection at 940 nm, because of the availability of high power (several watts) LEDs. We demonstrate the possibility to make long-distance (>150 m) detection, as well as time-gated detection. This opens new perspectives relative to the use of PbS for low-cost near-and short-wave infrared detection [START_REF] Tang | Towards Infrared Electronic Eyes: Flexible Colloidal Quantum Dot Photovoltaic Detectors Enhanced by Resonant Cavity[END_REF][START_REF] Tang | Dual-Band Infrared Imaging Using Stacked Colloidal Quantum Dot Photodiodes[END_REF] and imaging setup. [START_REF] Rauch | Imaging with Quantum-Dot-Sensitized Organic Photodiodes[END_REF][START_REF] Temple | Towards Low-Cost Infrared Imagers: How to Leverage Si IC Ecosystem[END_REF][START_REF] Klem | Colloidal Quantum Dot Photodiodes for Low-Cost SWIR Sensing[END_REF]

DISCUSSION

We start by synthetizing PbS nanocrystals with a peak band edge at 920 nm, [START_REF] Hines | Colloidal PbS Nanocrystals with Size-Tunable near-Infrared Emission: Observation of Post-Synthesis Self-Narrowing of the Particle Size Distribution[END_REF] see Figure 1a. This wavelength is just below the targeted wavelength at 940 nm in order to take into account the redshift occurring during the ligand exchange procedure needed to build a conductive film. The diode structure follows the one proposed by Chuang et al. [START_REF] Chuang | Improved Performance and Stability in Quantum Dot Solar Cells through Band Alignment Engineering[END_REF] A thick tin-doped indium oxide (ITO) layer coupled with a TiO2 layer is used as electron extractor. The absorbing layer is made of two layers of PbS. A thick (200 nm) n-type layer is built from a PbS ink [START_REF] Kim | Butylamine-Catalyzed Synthesis of Nanocrystal Inks Enables Efficient Infrared CQD Solar Cells[END_REF] with a high concentration (250 mg/mL) and I -as capping ligands. A top p-type layer (≈20 nm) is deposited using a solid-state ligand exchange with ethanedithiol (EDT) as capping agent. The n-and p-type nature of each layer has been confirmed using ion-gel field effect transistor measurements, see figure S1. Finally, a thin MoO3 layer (10 nm) and gold contacts (80 nm) are used as hole extractor, see Figure 1b andc.

The I-V curve of the diode presents a strong rectifying behavior, see Figure 1d. The dark current at 0 V can be below 7 nA.cm -2 , which is quite similar to the one reported for InGaAs sensor. Under illumination by a 940 nm LED (at power density close to solar cell applications), the open circuit voltage reaches 0.52 V. This is slightly smaller than the 0.6 V value usually reported for solar cells, but the illumination here is quasi-monochromatic while solar light contains much higher energy photons. The short circuit current is 12 mA•cm -2 , corresponding to a responsivity of 0.2 A.W -1 (EQE = 26%). The 0 V signal-to-noise ratio is higher than 10 6 . See the table S1 for a comparison of the performances of the obtained diode with existing devices based on PbS nanocrystals.

The detectivity of the device has been estimated under low incident flux, see Figure S3a. Surprisingly, the noise is limited by white noise and no 1/f contribution [START_REF] De Iacovo | Noise Performance of PbS Colloidal Quantum Dot Photodetectors[END_REF][START_REF] Liu | 1/f Noise in Semiconductor and Metal Nanocrystal Solids[END_REF][START_REF] Lai | Low-Frequency (1/f) Noise in Nanocrystal Field-Effect Transistors[END_REF] has been identified in the measured frequency range (1 Hz to 1 kHz), see figure S3b. Two factors tend to reduce the 1/f contributions which is generally the limiting contribution for the noise in nanocrystal array. First, the internanoparticle coupling is quite strong thanks to short ligand and this was identified as the main parameter driving the 1/f noise magnitude. [START_REF] Liu | 1/f Noise in Semiconductor and Metal Nanocrystal Solids[END_REF] Secondly, due to its relative wide band gap nature (compared to mid infrared material), the device is quite resistive. The detectivity of the device at room temperature is 2 × 10 12 Jones, see Figure S3c. As the device aims at being operated under low incident photon flux, we have quantized the power dependence of the responsivity, see Figure 1e and S4. As often observed for nanocrystal-based photodetectors, the quantum efficiency is better under low photon flux and typically improves by a factor 10 as the photon flux is reduced by three orders of magnitude. A second figure of merit which is not accounted in the case of solar cells is the time response of the diode. Under 1 ns pulsed illumination, the rise time is 10 ns and the decay time is close to 1 µs, see figure 1f. This decay time is compatible with the RC time constant measured at high frequency (1-10 µs, see Figure S5). Impedance measurement reveals that the capacitance is almost independent of the frequency. As a result, under illumination the resistance of the sample drops and so does the RC time constant. This makes the turn on time significantly shorter than the decay time. Such time response is much faster than the one reported for PbS in photoconductive geometry. [START_REF] Konstantatos | Ultrasensitive Solution-Cast Quantum Dot Photodetectors[END_REF] This is the combination of many factors (i) short ligands lead to higher carrier mobility which combine with shorter electrode spacing and tend to reduce the transit time, (ii) switch to diode geometry suppress gain and make dynamics no longer limited by traps lifetime (at the cost of reduced gain), it also change the device capacitance and the RC relaxation time constant Fast and intense response under low excitation flux are of utmost interest for the targeted pulsed active imaging application.

We then measure the photocurrent spectrum of the device and find it to be slightly blueshifted compared to the PbS film absorption spectrum, see Figure 2a. To understand this shift, we conduct electromagnetic simulations of the photodiode structure, using a frequency-domain modal method known as the Rigorous Coupled Wave analysis (RCWA), [START_REF] Hugonin | Reticolo Software for Grating Analysis[END_REF] see part 4 of supplementary information for details about the simulations. On part d, e and f of Figure 2 we respectively simulate the absorption map of the PbS layer, the ITO/TiO2/PbS stack and the full diode structure. Simulation reveals that (i) loss in the contacts (both in ITO and gold) are a significant part of the total absorption (≈28 %), see Figure 2c, e and f. These losses are the result of the metal [START_REF] Olmon | Optical Dielectric Function of Gold[END_REF] and ITO [START_REF] Holman | Infrared Light Management in High-Efficiency Silicon Heterojunction and Rear-Passivated Solar Cells[END_REF] absorption in the visible and near infrared. This problem remains mostly unaddressed for the design of solar cell while it may offer interesting perspective of improvement (ii) the diode structure introduces a Fabry-Perot resonance around 920 nm, see Figure 2c, and is responsible for the blue-shift of the photocurrent with respect to the absorption. Interestingly, this resonance spatially locates the maximum of absorption in the PbS film and not in the vicinity of the ITO contact, and rather close to the pn juction formed by the pbS(I)/PbS(EDT) interface. As a result the electromagnetic field is maximized where the electric field is also maximized. This explains the good efficiency of the current device in the near infrared. On the other hand, this will not be the case for shorter wavelength (with higher absorption coefficient) and this device appears not to be optimal for a solar cell perspective Due to the Fabry-Perot resonance, the absorption magnitude is enhanced by a factor 5 when thin film (200 nm) of PbS are used. Increasing the film thickess (300 nm) is not really improving the device absorption since the increase of the PbS absorption layer is balanced by the reduction of the enhacement factor, see Figure S8.

Figure 2 : (a) Photocurrent of the full device (red) and absorption measured in transmission mode of the glass/ITO/TiO2/PbS stack (black) spectra of the device. (b) Simulated absorption spectra of a PbS layer on glass (black), a PbS layer on ITO/TiO2/glass (blue) and the device (red). (c) Absorption ratio of the device (red) and PbS on ITO/TiO2 (black) over PbS film absorption. Figures (d), (e), (f) correspond to the modelized layers (left figure) and absorption distribution over the layers (right figure) under top illumination.

In NIR active imaging, the contrast observed on images results from differences in absorption and diffusion coefficients. This is typically useful for material sorting in order to discriminate the nature of illuminated objects. To mimic this application, we use a 940 nm laser source and shine its light onto plates made of different materials. We then measure the intensity of the scattered light at 0 V bias, see figure S6 for a scheme of the setup. The magnitude of the scattered light changes by almost three orders of magnitude depending on the material scattering the light, see figure 3a. This demonstrates the PbS photodiode ability to obtain pronounced contrast from a complex scene.

Outdoor active imaging requires collecting photons scattered over a long distance. As a proof of concept, we have tested the potential of our sensor to detect light scattered by a building located 85 m away from the source. A 10 W LED flashlight emitting at 940 nm is used as a source and is shone on the building in front of our laboratory (the estimated distance is 85 m, see Figure 3c). The collected signal is presented on Figure 3b. Even with a propagation distance around 170 m, a reasonable signalto-noise ratio (≈ 3) is obtained.

Figure 3 : (a) Photocurrent of different materials from retrodiffused 940 nm laser light normalized by the photocurrent detected with a metallic plate. (b) Photocurrent modulation measured at 100 Hz as a function of time in a long range detection configuration. (c) Scheme of the long-range active imaging. A light source (10 W/940 nm lamp) enlights a building at a 85 m distance. The device detects retrodiffused light from the building.

A second approach of active imaging is time-gated active imaging. The concept is to collect light after a delay to build an image corresponding to a given distance between the source and the scattering center. LIDAR detection is typically based on this concept. This obviously requires a fast detector where the rise time needs to be shorter than the light propagation time. In addition, the decay time of the photodetector needs to be also shorter than the inverse of the repetition rate of the illumination source. The fast time response of the diode at 0 V bias, shown in Figure 1d, is quite promising for such an application. We use a 1 ns pulsed laser and tune the propagation distance from ≈ 2 m and up to ≈ 18 m, see Figure 4a. The PbS photodiode signal is collected on a GHz oscilloscope while a fast (50 ps) time response silicon diode is used as trigger. It is worth mentioning that we do not even use any amplification stage for this experiment. As the optical path is extended, we measure a clear increase of the delay between the reference signal from the fast photodiode and the one from the device, see Figure 4b. This delay is fully correlated with the light propagation distance, see Figure 4c. This validates the potential of the PbS photodiode for time gated imaging and its use to reconstruct a 3D scene.

We have revealed the potential of PbS solar cells used as near-infrared sensors for low cost active imaging at 940 nm. This conventional solar cell diode actually achieves large photoresponse (up to 0.5 A.W -1 under low photon flux) and fast time response (10 ns). Using electromagnetic simulations, we have determined that the diode structure introduces a Fabry-Perot resonance which leads to a small blue-shift of the response. We also unveil that the absorption losses in the contacts represent 28% of the incident flux and this problem will have to be addressed in the future. We have demonstrated the ability of the PbS photodiode to obtain contrast in complex scene, ability to make long distance detection at least up to 170 m and finally to be used for time-gated active imaging. Future work will have to expand these results to longer infrared wavelengths. [START_REF] Cryer | 300 nm Spectral Resolution in the Mid-Infrared with Robust, High Responsivity Flexible Colloidal Quantum Dot Devices at Room Temperature[END_REF][START_REF] Killilea | Pushing PbS/Metal-Halide-Perovskite Core/Epitaxial-Ligand-Shell Nanocrystal Photodetectors beyond 3 µm Wavelength[END_REF]

METHODS

Chemicals: Octadecene (ODE, Acros Organics, 90%), Lead oxide (PbO, Strem Chemicals, 99.999+%-), Oleic acid (OA, Alfa Aesar 90%), Hexamethyldisilathiane (TMS2S, Sigma Aldrich, synthesis grade), Ethanol (VWR, >99.9%), n-Octane (SDS, 99%), n-Heptane (Merck, >99%), n-Hexane (VWR, 99%), Toluene (Carlo Erba, >99.8%), N,N-Dimethylformamide (DMF, Sigma Aldrich), Hydrochloric acid (HCl, Mieuxa, 25%) Ammonium iodine (NH4I, Alfa Aesar, ≥ 99%), 1,2 Ethanedithiol (EDT, Fluka, 98%)

PbS nanocrystal synthesis:

The procedure is inspired from Hines et al. [START_REF] Hines | Colloidal PbS Nanocrystals with Size-Tunable near-Infrared Emission: Observation of Post-Synthesis Self-Narrowing of the Particle Size Distribution[END_REF] 0.9 g of PbO are introduced in a 100 mL three neck flask with 3 g of OA and 47 g of ODE. The flask is degassed under vacuum at 120 °C for 2 hours. Meanwhile, in an air free glove box, a mixture of 420 µL of TMS2S and 10 mL of ODE is prepared in a 20 mL vial, then introduced into a 20 mL syringe. The atmosphere of the flask is switched to Ar and the temperature is set equal to 90 °C. The TMS2S solution is quickly injected and the solution turns dark while the temperature drops to 80 °C. After 8 min at 80 °C, the reaction is stopped by removing the heating mantle and prompt cooling of the flask by addition of a mixture of heptane and OA. The nanoparticles are then precipitated by addition of ethanol. The formed pellet is redispersed in toluene. A second step of cleaning is repeated. Finally, the pellet is redispersed in toluene with a 50 mg.mL -1 concentration. The solution is centrifuged to remove any colloidally unstable material. Finally, the solution is filtered on a 0.22 µm PTFE filter.

PbS Ink preparation:

A solution of NH4I at 60 mg.mL -1 in DMF is prepared by sonication. 2.5 mL of this solution is introduced in a test tube. On the top of this polar phase, 2.5 mL of PbS nanocrystal solution at 50 mg.mL -1 is deposited. The two phases are then mixed and we observe a phase transfer. The clear non-polar phase is discarded and the DMF solution is cleaned three more times using hexane. Finally, the particles are precipitated by introducing ethanol in the tube. After centrifugation the formed pellet is redispersed in fresh DMF with a concentration of 250 mg.mL -1 . The solution is finally centrifuged to discard any unstable material.

Solid state ligand exchange:

A solution at 1% in mass of EDT in ethanol is prepared. A drop of PbS nanocrystals solution in hexane:octane (9:1 volume ratio) is drop-casted onto the electrodes and left to dry. The resulting thin film is dipped in the ligand solution and rinsed with acetone. Once the film is dried, a second layer of PbS nanocrystals is deposited and the ligand exchange step is repeated. The deposition process is performed two times in total.

ITO patterning:

We start from commercial glass/ITO substrates of 30x30 mm² with a low sheet resistance (7 Ω/□). Substrates are cut into 15x15 mm² pieces and cleaned by sonication in an acetone bath during 5 min. The cleaning procedure is followed by rinsing the substrates with acetone and isopropanol, then dried with a dry N2 flow. AZ 5214E photoresist is spin-coated for 30 s, then baked at 110 °C for 90 s. A standard photolithography process is performed using mask aligner for exposing the substrates to UV light for 5 s through a lithography mask (1 mm width). Photoresist is developed using AZ 726 developer for 20 s and immediately rinsed with deionized water. After that, exposed ITO surface is completely etched out with 25% HCl (in water) for 15 min at 40 °C, and substrates are immediately dipped into deionized water. Then, we conduct lift-off process in an acetone bath and patterned ITO substrates are cleaned with acetone and isopropanol. Finally, substrates are dried with dry N2 flow. TiO2 film preparation: TiO2 films are prepared from a commercial solution (SOLARONIX Ti-Nanoxide HT-L/SC). The solution is dropped on heated patterned ITO (110 °C) and spin-coated at 5000 rpm during 30 s. The pre-heating process is required in order to improve the solution wetting. Resulting ITO/TiO2 sample is then heated at 450 °C during 15 min and its thickness is measured to be 120 nm with DEKTAK profilometer.

n-doped PbS ink deposition: A 250 mg.mL -1 solution of n-doped PbS ink is used for the active material layer. 60 µL of this solution is deposited on the ITO/TiO2 substrate and spin-coated at 1000 rpm during 60 s followed by 2000 rpm during 240 s. The procedure is repeated twice. Depositions are performed in air-free environment.

p-doped PbS: 60 µL of a 30 mg.mL -1 of OA capped PbS in toluene is deposited on the ITO/TiO2/n-doped PbS substrate and spin-coated at 2000 rpm during 30 s. A solid-state ligand exchange (see above) is then performed. This procedure is repeated twice. Depositions are performed in air-free environment.

MoO3/Au deposition: After the deposition of PbS layers, the device is transferred from a glovebox to an evaporator while keeping an air-free environment. After the glovebox-to-evaporator transfer and once a vacuum around 5.10 -6 mbar is reached, 10 nm of MoO3 followed by 80 nm of gold are evaporated. The sample is then stored in air-free environment.

ASSOCIATED CONTENT SUPPORTING INFORMATIONS

Additional information about material characterization, diode and transistor fabrications and characterization, contrast-resolved measurement, noise and detectivity characterization, power dependent measurements, RC characterization as well as details about modelization are given in supporting information.

Figure 1 :

 1 Figure 1 : (a) Absorption spectrum (black) of PbS CQDs as synthetized (ligands: oleic acid (OA), solvent: toluene) and emission spectrum (red) of a 940 nm LED. Backfront: TEM image of PbS CQDs. (b) Scheme of the built diode. (c) Cross-section SEM image of the diode. (d) Dark current (black) and current under 940 nm excitation provided by a 940 nm LED (red) of the device. Some characteristics of the device are shown inset. (e) Diode responsivity at 0 V vs excitation provided by a 940 nm laser. (f) Time response of the device when excited by a 355 nm pulsed laser (1 ns pulse). Time constants τon and τoff are obtained through a single exponential fit.

Figure 4 :

 4 Figure 4 : (a) Scheme of the setup used for time-gating experiment. (b) Device response at 0 V as a function of the total distance from the source. The bottom black curve corresponds to the silicon photodiode (PD) response used for triggering. (c) Comparison between measured distances with a meter (X axis and red line) and deduced from ∆t determination. The red line is defined by y=x equation.

ACKNOWLEDEGMENTS

We thank Nexdot for providing the nanoparticles. EL thanks the support ERC starting grant blackQD (grant n°756225). We acknowledge the use of clean-room facilities from the "Centrale de Proximité Paris-Centre". This work has been supported by the Region Ile-de-France in the framework of DIM Nano-K (grant dopQD). This work was supported by French state funds managed by the ANR within the"Investissements d'Avenir" program under reference ANR-11-IDEX-0004-02, and more specifically within the framework of the Cluster of Excellence MATISSE and also by the grant IPER-nano2, Frontal, Graskop and Copin.

For Table of Contents Use Only


published or not. The documents may come     Changes in work ethic in eastern Europe: the case of Romania

Changes in work ethic in eastern Europe:

the case of Romania

Monica Heintz*

At the end of the 1990s, faced with constant poor economic results despite the acclaimed introduction of free market economy structures in eastern Europe, officials as well as social scientists, in the West as in the East, started to assert that introducing new capitalist structures without accompanying them by the corresponding capitalist values will bring no results. One of these values, which without being always explicitly addressed, was always implicit in the examples of negative eastern economic behaviour, is "work ethic". In order to understand these negative judgments on Romanian work ethic, I conducted my fieldwork on the values pertaining to work revealed through discourses and practices in workplaces, without limiting myself to observing how the capitalist ideology of work (work ethic) translates in practice. My construction of the field of work values finds its first inspiration in Max Weber's seminal work, The Protestant Ethic and the Spirit of Capitalism [START_REF] Allen & Unwin | The Protestant Work Ethic and the Spirit of Capitalism[END_REF][START_REF] Allen & Unwin | The Protestant Work Ethic and the Spirit of Capitalism[END_REF]], but goes further to explore the interplay between work ideology and practice, thus showing to what extend practices are capable of influencing values. My inquiry into the ethic of work in Romania is based on the results of an ethnographic inquiry conducted in 1999-2000 among service sector employees in Bucharest. I first present the ideologies of work at the turn of the 21 st century in Romania, then I describe the ideologies and their (corresponding) practices in three service sector organisations. Lastly I conclude by showing why it is improper to refer to a "Romanian work ethic" (in the Weberian sense), despite the fact that work is valued and a certain ethic governs Romanian workplaces. Indeed, taking work ethic in its (capitalist) ideological sense as international organisations and Romanian officials do and measuring Romanian practices against it, is nothing else but an ethnocentric move that blinds the analyst to the existence of a vast field of values linked to work, which evolve in a different frame, that of an ethic of human relations.

Work ideologies

The communist ideology of work

The ideology of work is the result of the elaboration of several political beliefs and ideas in a particular social and historical setting [START_REF] Buckley | Women and Ideology in the Soviet Union[END_REF]. In a socialist system, these ideas constitute a unique theoretical interpretation of reality, over which the Communist Party has a monopoly, while in a democratic society several competing ideologies can co-exist in the public space. In liberal systems, the ideology of work is influenced by actual practices and claims (like the 1968 demonstrations in the West), whereas in socialist systems the leaders decide what the "appropriate" interpretation of the doctrine is at a given time [Buckley, 1989, p. 5]. The ideology of work in Romania during the socialist period was the result of the "pure" Marxist ideas about work and of the practical Marxist interpretation elaborated by the Romanian Communist Party, the president Nicolae Ceau ş escu and the Ministry of Culture.

Marx viewed work as both rewarding and alienating, depending on the relations of production in which it is performed. Through work, man transforms the objects of his environment: he satisfies his needs, gives them value and transforms them into possessions that define him. Work defines an individual's identity. But if these products of labour are taken away from him, his self is alienated. Work is then alienation [Ortiz, 1979, p. 210].

State socialism assured that everybody had the right to work and that workers were the masters of their own work. This however led to a "commoditisation of labour" [Lampland 1995] as much as under capitalism: work became an object sold to the state in exchange for social advantages. Propaganda about commitment to work was the main incentive that officials could supply, given that no real financial incentives that would have introduced inequalities among workers could be given (as the case of Stakhanovism shows). Phenomena like Stakhanovism and model farms, and the way they were dealt with locally, reflect the socialist ideology of work at a given time.

Work was dedicated to the common good and had an aim: the construction of a "socialist multilaterally developed society" and the advancement towards communism. The fact that under the desired communism everybody was supposed to be rewarded "according to her/his needs", while an ascetic lifestyle was vaunted, meant that there was no reason for unlimited work for the sake of accumulation, which characterises the Protestant work ethic.

The ideology of work did not directly address the issue of services, because this sector did not produce anything enduring, being just complementary to the other economic sectors. Given that the aim of trade (the main form of service in the past) is profit, trade in communist ideology was reduced to a system of redistribution of products to which everybody was entitled and which bore only superficial similarities to the profit-making trade (for instance by the use of money). Services in general were meant to support workers so that they could engage in productive labour. This very brief overview of the socialist regime reveals the existence of fixed ideological, economic, political, and social structures, which together imposed the place of work in people's lives and their appropriate work ethic. The state assigned a workplace and a duty to everybody -to contribute to the development of socialism -and her/his work was a contribution to the development of socialism. Having a workplace was thus sufficient for fulfilling one's duty towards the state, which guaranteed in exchange a (quite undifferentiated) reward and social security. The socialist work ethic, initially one of enthusiasm and willingness to give to society, in practice takes on a mechanical form: it is asserted but not believed. As work becomes a constraint (as was the case during the socialist period), it does not need to be a calling. On the contrary, as its reward is often seen as unsatisfactory, work will actually be undermined as a protest against the system. As a Romanian joke puts it, "They pretend they are paying us, so we pretend we are working" (Ei se fac c ǎ ne pl ȃ tesc, noi ne facem c ȃ muncim) [Verdery, 1983, p. 29]. Examples from the economic and political sphere show that non-ideological resistance and negotiation were prevalent under socialism. This is the "actually existing" work ethic that would influence the perception of work after 1989.

The "Capitalist" Work Ethic

The conceptualisation of the Protestant (work) ethic in the social sciences originates in Max Weber's work on the origins of capitalism [1984 (1930)]. Weber refers back to Protestant teachings from the seventeenth to the nineteenth centuries to describe a particular ethic of life, labelled a work ethic because it is centred on work. The highest form of religious/moral obligation was to succeed in worldly affairs (this is known as "the calling") and success became a sign of being "chosen". Thus, work was transformed from a necessity (to satisfy survival needs) into a calling -work for the sake of work, for the infinite accumulation of wealth and for its minimal enjoyment.

The work ethic defined by Weber is no more than an ideal type, closer to an ideology than to an ethic encountered in practice. Bauman warns: "Weber's tale is not and never was an account of a historical event" [1987, p. 150]. Weber has actually never claimed that Christian treatises or the teachings of self-made men like Benjamin Franklin formed the reality of that time. Subsequent writers like Anthony [1977] indeed assume the existence of a monolithic PWE and contrast the current values of work met in practice with past ideals as they stem from Protestant teachings. Joyce [1987] criticises this stance and shows the heterogeneity of values existent at any one time, which vary depending on social class and type of enterprises/industries, and highlights a more complex link between values and practice. The work ethic was "the gospel of the bourgeoisie" and did not penetrate in its ideal form into the working class. This ideal was meant to serve the needs of industrial development for time organisation, speed, and regularity. Bauman concludes that the work ethic was a means for the upper class to maintain social order [1998]. Applebaum shows that the heterogeneity of values linked to work in Western countries is as great in the present as it was in the past. Work ethics vary between different capitalist countries as work values depend on the historical period, class, and occupations [START_REF] Applebaum | The Concept of Work: ancient, medieval and modern[END_REF].

The reflection of a capitalist work ethic in Romania

Romanians have access only to scattered images of this diversity of work values and practices, which arrive in Romania through media, foreign consultants, translations of Benjamin Franklin or of new books on image-production, friends recounting their experiences in the West, and Romanian immigrants in the West. Images retained from this proposed kaleidoscope, although slightly outdated, impress as novelties. Thus, Romanians admire the evidence of hard work, of the division of labour at the level of enterprises and society, of the lack of tricks and bribery, of apparently friendly but strong hierarchies, and they recognise these features as an ideal that is not put in practice in Romania. In the interviews I conducted, no reference was made to the values of an "aesthetic of consumption" [START_REF] Bauman | Work, Consumerism and the New Poor[END_REF], or to a balanced life. A capitalist work ethic (Western style) meant for most interviewees hard work; for a smaller group, work well done; and for a minority of intellectuals, intelligent organisation and management of human forces.

The multinational companies active in Romania impose an organisation of work which confirms these ideas: employees are required to work more than ten hours a day, a condition accepted because of the higher pay offered, and their work is thoroughly checked. In a software company working 24 hours a day, seven days a week, on line, even the five-minute toilet breaks are scheduled in advance and controlled, and a quality controller monitors the work performed, watching over employees shoulders [START_REF] Heintz | East European managers and Western management theories: an ethnographic approach of Romanian small and medium enterprises[END_REF]. Other multinational companies have health programmes, checking employees'blood pressure every day and providing them with lunch in their office.

I have discussed work values and working conditions in Western countries at length with my Romanian workmates and acquaintances. In this dialogue I revealed that practices and values in the West were quite different from the image of work in the West held by my interviewees, and quite different from the work conditions proposed by international companies in Bucharest. Some of my accounts surprised my interviewees, such as my statement that the division of labour has proved detrimental to the pride one takes in work, and that since the 1980s attempts to address this problem have advocated a transformation of work [Wood, 1989] in the West, from Fordist assembly-line work to more flexible specialisation. Another surprise was my assertion that Westerners would not necessarily take on two jobs just because they had the opportunity, or work 70 hours a week in order to prove their commitment to a job. The concept of privileging quality over quantity, or the rational calculation of gains and losses for establishing a balance between quantity and quality, seem to have no place in the ideology of the capitalist work ethic that arrives in Romania, which emphasises "hard work". As a result, new Romanian companies or foreign companies implemented in Romania impose what they take to be modern capitalist principles and propose values that do not suit the requirements of the post-industrial era. And when these companies propose different prin-ciples, their employees are those who still try to show their commitment by acting according to their own understanding of a work ethic derived from an un-criticised capitalist ideology (for instance by staying longer hours at work).

The information available to Romanians on the work ethic of current capitalist organisations is often inaccurate or propagandistic, a fact that hinders the positive role it could take by suggesting motivating narratives about work. The capitalist ethic of work serves as a term of comparison or as a model, but its complexity and contradictions are unknown. Thus the capitalist ideology of work is taken to correspond to actual work values in Western countries.

Work practices and work values in three service entreprises after 1989

I conducted ethnographic fieldwork in Bucharest from July 1999 to October 2000 in several service enterprises, working alongside the employees for four months in each of them. I chose to work in the service sector because of the difficulty to measure the output, which in turn leaves the employees with a greater freedom of developing their own attitude towards work. The difficulty of measuring their work performance was exacerbated in the case of three organisations described below, in which the service provided was information and education-or, as some employees put it, just "talk". After providing a short description of the three service organisations observed, I will look at the discourses of their employees and managers about work and at their practice and will briefly evaluate the result of this performance in terms of the success or failure of their human management programs.

Three service organisations in Bucharest

I have chosen to conduct fieldwork in organisations that represent different segments of the labour market, segments defined by the type of contract and the amount of pay proposed to their employees: a state institution that proposes secure but low wages to its employees; a private firm that proposes insecure and low wages; an NGO that proposes secure and relatively high wages to its employees. The first institution is state owned, the two others are private. This allows capturing the diversity of work configurations and work values and, through comparison, the elaboration of more general conclusions about work ethic in service enterprises.

The first of these organisations is a Music School that I will call "Gamma", a state school created in the 1950s to provide free complementary musical education to children in elementary school (ages 7 to 14). Around forty teachers exercise within this institution.

The second organisation, the NGO "Alpha", is a medium non-profit organisation first registered in 1991 in Romania and whose goal is to improve the life of a category if children with a mortal illness. The NGO is now the main service provider for these children, estimated at 6000 all over the country, having been quite successful in securing funding mainly from Western European sources but also from the Romanian government. Alpha has headquarters in Bucharest, where 10 employees work and, through one of its projects, another 30 employees work in seven locations all over the country. Work in these locations is in collaboration with state organisations (hospitals), on the basis of contracts established under the auspices of the funding agencies.

The third organisation is a marketing department, which is the core of the firm "Beta", first registered in 1997, which provides foreign language courses to adults. Despite the fact that this is an educational institution, like Gamma, the language used in order to define the organisation's relationship with its beneficiaries (in Beta they are "clients", not "pupils") is telling of Beta's real vocation, as is also the fact that at the heart of the organisation is the marketing department. The professorial body, less important numerically, plays only a secondary role.

Work ideologies determine the rules of conduct in workplaces

Managerial discourses provide an interpretation of the social world and its functioning, and explain and justify actions. They are one of the main ways of motivating employees and inducing a certain spirit, the "spirit of the enterprise", as well as the main way of providing the rules of conduct at the work place. These are meant to generate a certain work ethic among employees. Managerial discourses themselves are the product of ideologies. What I will show here is that these ideologies differ greatly from one organisation to the other, despite the fact that they are embedded in the same society. This shows the heterogeneity of ideas and values about work that exist simultaneously in the Romanian society.

In the marketing department Beta, the manager-owner calls for complete obedience on the part of his employees and imposes himself as a model to them. The words repeated daily are "You are here to shut up, listen and learn" and "the intelligent employee is the one who knows how to imitate his manager". His own model is an English manager under whom he worked in Indonesia for a number of years in the 1990's and who (as he asserts) even checked the cleanliness of their nails and hair as part of the daily control. Though he would not go so far, our manager would require a certain make-up, a certain lipstick colour, a certain length of hair and skirts from his employees who are all university students or graduates aged 20 years or more. The boss is always right and making him try to recognise his mistakes always ends up in threats and scandals. The counterpart is that the manager provides indeed his employees with useful practical courses of marketing strategy, taught with passion and certain professionalism. His tactics is to alternate coercion with paternalism (the stick and the carrot). His main advice: do not trust anybody in business. For the manager of Beta, both the workplace and the business world are competitive places, thus the rule of mistrust should be applied both within and outside the enterprise. Employees have no right to have their own ideas and depend on him for the smallest decision, under the threat of being fired. Despite the lack of real power of the intermediary managers in the organisation, hierarchy is very much emphasised by the manager. This is meant to impress potential employees invited to collective interviews and potential clients invited to buy a course. "Impressing" the client by word and gesture is a recurrent theme in the discourse of the manager; one concrete manifestation is the permanent rewriting of the employees'discourses, the constant revision of their capacity to "impress" the client.

The management of the NGO Alpha is situated at the opposite extreme, their manager trying to maintain a democratic regime, in which highly educated employees are encouraged to participate in management decisions. Every single employee is paid attention to and consulted before s/he is allocated an activity and monthly democratic meetings are organised for planning the activities of the enterprise. These meetings last forever and often do not lead to concrete results, because their goal is to reach an unanimous agreement and this is difficult, even where there are only ten employees. And though democratic voting could be used, the meeting is practically postponed until the manager privately persuades each employee of the qualities of the decision of the majority. Would this correspond to Marx's ideal of a willing and total embracing of a collective position by each individual? In a sense, yes, but it is not Marx who inspired this type of organisational behaviour, but the new directions in management, which encourage the recognition of the value of each employee and the creation of a family spirit based on sympathy and responsibility, not on control, as a guarantee of the good-working of the organisation. The response of the employees however is a permanent criticism of "the lack of organisation" and realistic management in the organisation, though they would never point at the manager as responsible for it (except in confidential conversations we had outside the workplace). As for the manager, he admits the lack of organisation, but does not identify the principles on which the management is conducted as being its cause and in general does not feel particularly responsible for it (several managers were simultaneously in charge, with overlapping responsibilities at the time of my fieldwork; certainly, them being many, responsibility slipped somehow from one to the other).

The ideologies involved in the management of the two private organisations could easily be labelled, for they are constantly apparent in managers'discourses: fierce capitalism for the marketing department, democracy for the ONG. One can recognise pieces of management theories: the fierce capitalism corresponds to the idea that, after all, enterprises exist to make profit (as opposed to enterprises of the socialist era); the democracy corresponds to the contemporaneous neo-human relations: "make your employees responsible in order to motivate them and use their creative resources" theories. Foreign consultants-like true missionaries-have introduced Western management theories in Eastern European countries as new religions [START_REF] Kostera | The Modern Crusade: The Missionaries of Management come to Eastern Europe[END_REF]-neither to be questioned, nor to be criticised.

The rules of conduct in practice I will show how these ideologies translate in the practice of human management and analyse whether managerial discourses provide a useful and efficient framework for the activity of the employees. The two private enterprises observed offer completely different models of management practice, while the state and the private organisations are different with respect to employees'work.

In Beta, human management practice (except for its hardcore of hiring, firing, payment etc) is realised chiefly through discourses. Beta is a "one-man show": the "boss" points out through daily behaviour that he has the power to decide the fate of his employees as they are part of his business, while employees do not protest when they are on duty and fulfil the requirements. The manager makes all the business decisions. This control is tight because he does not trust any employee or lower level manager. The only voice one hears in the public space of the firm is his, when he criticises in very harsh terms or praises in dithyrambic words his employees. On their side, employees would spend their time criticising the manager and planning when to quit the enterprise. It is interesting to note that all these whispered gossip is conducted while employees wait for their turn to work (i.e. wait for their clients), in the same room in which sales activities are going on and in which the manager is also present! As for the language teachers, the manager ignores them almost totally, because they do not bring him money in a visible way (the payment for the entire course is obtained before the course starts). Thus for instance he loosely controls their punctuality and is concerned only with their appearance, as this could affect the decision of prospective clients who pass by. All his attention is directed to the marketing department, in which he is always present, again from fear of delegating control to employees. Through a window the manager watches his employees at work with potential clients and he intervenes in their work when the required energy seems to desert them. The target being only to attract clients, and thus money, as quickly as possible, every potential client is of the utmost importance and every failure of the employees to transform her/him into a client is examined, judged and followed by a training session, which means showing over and over again how work should be done. This is stimulating for the employees as they have a continuous feedback on their work and interest shown in it. Employees obey through fear, as the boss could turn quite violent. The only form of protest they use is quitting the enterprise or collective whispered gossiping. Their pay is decided exclusively by the manager and cannot be negotiated. It is low and completely uncertain -the employees being paid depending on sales, with no fixed wage -, while the employees could daily witness how large amounts of money are handed to the owner/manager when courses are bought.

The management strategy of the NGO Alpha is to maintain an informal, familial atmosphere at the workplace and not to insist on control. The lack of formal assessment of employees'activity gives them freedom, but means also less interest from the management and consequently less value for their work. If employees are sometimes praised for their efforts or criticised for their failures, observations remain abstract, undirected and uninformed, which deprives them from the capacity to motivate and support further activities or to propose a solution to the problems of the organisation. It is impossible for the management to be better informed because they have their own tasks in which the evaluation of employees is scheduled only occasionally, and titled "learning what they do so that we can help them better". Everybody has to report directly to the Romanian general manager and this makes information impossible to handle. We should remind that this manager is not the ultimate decision maker, but has to report to a Western consultant, in order to receive instructions. The Western "consultant" is not based in Romania and does not speak Romanian, thus making communication difficult and delaying decisions. The main problem identified by the employees themselves is lack of communication and decision-making. These problems apart, employees are relatively satisfied wit their work in the organisation: their pay is 2-3 times higher than the average Romanian wage and the activity of the organisation (which has a humanitarian character) generate human satisfaction. Employees often do benevolent extra-hours at work or at home, as they understand that they have tasks to finish, not just hours of "sitting with the buttock on a chair", as the intermediary director puts it. Everybody is her/his own manager and picks up among the duties to be performed those that are the most urgent or most preferred. But nobody undertakes to co-ordinate these activities, which complicates things, given that all projects are common.

In the Music School, strategic management is provided by the state and the director's task is only to solve problems raised by contradictions in state directives. Alternative jobs tire the employees, who are rushing between different commitments, among which their school job comes last, as it is stable and does not need to be fought for. The director of the school warns discreetly teachers about absences or late arrivals, which appears to be enough to bring them back on track for a while. Being herself a teacher the director refuses to evaluate her colleagues, leaving this duty to the Ministry of Education, who conduct a bureaucratic assessment. All organisational problems (conflicts between teachers regarding the distribution of classrooms, timetables etc) have to be solved privately, through friendly visits or phone calls. The relations in Gamma are horizontal, and not vertical as in Beta.

The immediate conclusion from the field analysis of the two private organisations is that rules are respected, but that they are not effective. The first proof of their lack of efficiency is employees'turnover: every six weeks in the marketing department (less among teachers), every one or two years in the NGO. In Western countries this is a sign of employees'dissatisfaction with their jobs, as Lawler established through empirical studies as early as 1973 [1973]. Unexpected and frequent turnover brings considerable losses to Alpha and Beta. In Gamma, where turnover is inexistent, dysfunctions are revealed by the disengagement from work, which leads to the socialist "pretending that we work". What these three ethnographic cases also show is that there is no simple transfer of ideologies from the top (managers) to the bottom (employees). Managers and employees derive different ideas from their position in the enterprise and also play back the discrepancy between discourses and practices of management.

A Romanian work ethic?

The empirical material analysed makes us question the existence of a Romanian work ethic-first by showing the heterogeneity of work values in Romania, second by showing the potential of practices to continuously fashion values that leads to an ever changing work ethic in this period of rapid social changes, third by showing that the ethic governing workplaces is an ethic of human relations rather than an ethic of work per se.

The Romanian work ethic -a heterogeneous set of values

This brief analysis shows that the three enterprises observed are very heterogeneous with respect to rules and their enforcement, varying from a strict imposition of rules in the marketing department at Beta, to an absolute freedom of movement and thought in the NGO Alpha, where only some principles are presented to the employees; from sets of rules (principles) with their own internal coherence in Alpha to incoherent measures in the Gamma Music School; from Fordist totalitarian rules in Beta to democratic idealism in Alpha. In contrast to the uniformity of the socialist period, today the ideology of work differs across enterprises, depending on the position of enterprises in the labour market or on individual circumstances.

Even inside each enterprise, managers appear unable to provide a coherent, realistic image of the desired work ethic, themselves living under the influence of different "ideoscapes" [Appadurai, 1991]: echoes of the ideal-type of the Protestant work ethic pierce through the typical "new rich" discourse [START_REF] Wallman | Turning Money into Culture: "Distinction" among Eastern Europe's Nouveaux Riches[END_REF] of Beta's manager; echoes of Christian moral values are felt in the discourses of the director of Gamma, who is a practising Christian; echoes of the ideal-type of the socialist work ethic unconsciously penetrate the discourses of the intermediary manager of Alpha. To this we can add their concrete life experiences of the capitalist work ethic (for the Beta manager and an interim manager of Alpha, who had worked abroad), and that of the "actually existing socialism" (for the Alpha interim manager and the Gamma director). A third layer of influences comes from their knowledge of ways to turn values around in daily practice, in good conscience. The mixture of these often-incompatible ideologies and practices does not provide an efficient code of behaviour or motivating discourses for the employees. For instance in Alpha, where hard work is highly valued and employees strictly selected, managers did not fire those found to be useless or lazy, because "they needed money too". Thus, the driver, rendered useless by the fact that everybody in the NGO used her/his own car for business travel, was fired only after he had committed several thefts from the NGO's premises.

With no coherent or convincing set of values offered, with rules that prove insufficient or impractical, employees are left on their own to establish the way they would behave at work, towards colleagues, managers or customers.

Redefining work ethics through practice

From the ethnography of my three main field sites, it appears that dysfunction can arise even when rules are internally coherent, the structure of power allows them to be enforced, and when the rules of conduct fit (theoretically) the needs of the organisation. This is because employees also interpret the rules in light of their understanding of work derived from the larger social context, and they fill the existing gaps with their own rules/interpretations. Opinion leaders, politicians and managers may try to change values by imposing them from above, but people would still influence them from below through their practices. Work practices influence work ethics, and the attempted creation of or change in a work ethic that remains a purely theoretical, ideal endeavour has few chances to survive. The socialist state, which played deaf to the voice from below and tried to educate people "in the spirit of work", finally collapsed. Current sociologists and social historians [START_REF] Bauman | Work, Consumerism and the New Poor[END_REF] overlook the importance of ordinary people's practices, which forced leaders to change their discourses and mobilised values over time. Leaders are motivated to adapt their discourses by attempts to maintain social order. A work ethic may change through an encounter with other sets of values, but also under the pressure of employees'interpretations of rules as revealed through their practice.

Practices that do not conform to values are not necessarily perceived as deviant, because justification -as Wedel [1992] showed for Poles under socialism -or interpretation, which is often the result of negotiation, can make them compatible. Taken individually, in her/his own economic and social context, each employee has reasons for behaving in a certain way. Rather than being directed by her/his own personality and work values, s/he undergoes internal moral conflicts when s/he deviates from these rules. Managers respond with their rules, which distance employees from adherence to their original values, until a relative state of equilibrium is reached. These new values and rules are at a certain distance from the ideal. The negotiation is double: both between different categories of staff (typically subordinates versus their managers) and between values (ideal) and practices (real).

An ethic of interpersonal relations

As a work ethic is linked to money and survival, other spheres of ethics constantly feed it. One example is cheating at work: in most service enterprises this comprises cheating another person, which bears on the ethic governing interpersonal relations. Furthermore, it is even questionable whether the values encountered in the workplace are linked to work and not to personal commitments -towards the employer, other employees, or clients. Several ethnographic observations have led me to question the existence of a particular ethic linked to work.

Lack of pride in one's work is frequent, and relegates work to the level of a means of subsistence and not of a provider of identity. Work practice is not necessarily the reflection of certain work values, but may be only the result of life constraints. There is no need for work values if there are enough whips. Lengthy discussions about work commitments with my informants suggest however that only (temporary) historical vicissitudes have caused them to lose pride in their work, or to be more precise, in the status conferred by employment. Thus, the Music School teachers complained that the number of hours of teaching they had to do in order to secure their subsistence obliged them to do their work unconvincingly and without pleasure. Instrument teachers, however, are a particular category of employees among service employees, a vocational group, with a distinct professional ethic (a set of values pertaining to the profession of artist) even before having a certain work ethic. Most women employees under socialism used to take pride in the status conferred by work as superior to that of a housewife. Now they prefer to get early retirement by paying for false medical certificates in order to have both a pension and a reward from their work in the informal economy.

Given the loose control exercised on some categories of employees, notably state employees, and the difficulty of evaluating work in service enterprises, we could wonder what values motivate the employees to perform their work at all. We should note at this point that work contracts in 1999-2000 had almost no value if not endorsed by a personal commitment -trust -between employer and employees (which generally precedes the signing of a contract), as the state could not enforce contracts satisfactorily (failure to respect the contract was sanctioned only at the end of a lengthy and expensive legal procedure, that made it ineffective). Also, work commitments tend to be more respected between people belonging to the same social circle or network. Work requirements are often manipulated to satisfy a (recommended) client. The employee who does this often has "a good and understanding" nature. In the marketing department of Beta, sales representatives happened to forget their own financial interest and their work commitments when obeying an inner obligation to be sincere toward a client. Personal contacts in service enterprises make work practices linked more to an ethic of human relations than to an ethic of work. Impersonal relations facilitate trickery or poor work performance; cheating the abstract state carries no moral responsibility. Therefore, an employee is motivated to work not by a sense of responsibility toward an abstract work requirement, but rather by responsibility toward the employer, the client or fellow workers. It is interesting to note that in Western organisations today, there is an increasing focus on personal relations, corporate behaviour, and forging a family spirit [START_REF] Grint | The Sociology of Work: an introduction[END_REF][START_REF] Grint | The Sociology of Work: an introduction[END_REF]]. This would suggest that the capitalist work ethic has lost some of its power to motivate employees (as the state of abundance renders sustained work over the course of one's life less necessary) and needs to be replaced by an ethic inspired by the ethic of personal relations. This is also a re-establishment of a pre-industrial form of work, as Grint's history helix shows [1998Grint's history helix shows [ (1991), p. 321]), p. 321].

Therefore, values intrinsic to human relations, not work values, can be found behind work practices in Romania [see also [START_REF] Heintz | Be European, recycle yourself[END_REF]. Work values are socially embedded values, not impersonal values imposed by the economic organisation. Criticisms of the current work ethic (motivated by Romanians'misguided perception of the capitalist work ethic), current in the debates over the Romanian mentality, are the reflection of an incapacity to see the specificity of a work environment where human relations rank higher than work per se.

BIBLIOGRAPHY

ANTHONY P.D. [1977], The Ideology of Work, London, Tavistock Publications. APPADURAI A. [1991], "Global Ethnoscapes: Notes and Queries for a Transnational Anthropology", in R.G. Fox (ed.), Recapturing Anthropology: working in the present, Santa Fe, School of American Research Press.