Papers by fabrice Goubard
Nanostructured Conjugated Polymer for Solar Cell Applications
Conjugated Polymer Nanostructures for Photocatalysis under Visible-Light (Key Note)
HAL (Le Centre pour la Communication Scientifique Directe), 2018
Electronic Materials Letters, 2014
Poly(3,4-ethylenedioxypyrrole) (PEDOP), combined with metalfree organic sensitizers, is efficient... more Poly(3,4-ethylenedioxypyrrole) (PEDOP), combined with metalfree organic sensitizers, is efficiently used for the first time as the hole-transporting material in solid-state dye-sensitized solar cells. Devices employing PEDOP as the hole conductor and D35 or D21 L6 as the sensitizer show a ten-times-higher energy-conversion efficiency (of 4.5 % and 3.3 %, respectively) compared to Ru-Z907-based devices. This is due to the efficient suppression of electron recombination.
Synthetic Metals, Jun 1, 2018
In this study, three donor-acceptor-donor triphenylamine/oxadiazole hybrids differing by the subs... more In this study, three donor-acceptor-donor triphenylamine/oxadiazole hybrids differing by the substitution pattern were synthesized and characterized by means of experimental and density functional theory (DFT) methods. The new compounds were used as hosts for the design of yellow-and green organic light emitting diodes (OLEDs), exhibiting very different EL characteristics. The position of the triphenylamine substituents relative to the central phenyl-oxadiazole-phenyl core was found to greatly influence the EL performances. The results indicate that the increased internal torsion and the disrupture of the interring π-conjugation of the hosts impacts importantly the triplet energies andthe EL performance of OLEDs. OLEDs fabricated with the best host afforded an external quantum efficiency (EQE) of 17.1%, a current and power efficiency of 59.3 cd/A and 29.5 lm/W while doping the emissive layer at 10 wt% with the triplet emitter Ir(ppy) 3 .
Dispersion of Luminescent Nanoparticles in Different Derivatives of Poly(ethyl methacrylate)
Journal of Nanoscience and Nanotechnology, Apr 1, 2011
Radiation Physics and Chemistry, Mar 1, 2021
As alternative radiolytic approach, the synthesis of P3HT was made possible thanks to the oxidati... more As alternative radiolytic approach, the synthesis of P3HT was made possible thanks to the oxidation of 3HT monomers by chloromethyl and dichloromethyl radicals or by their corresponding peroxyl radicals in situ produced by dichloromethane solvent radiolysis. Under two different experimental conditions, in oxygen-free solution and in oxygen-saturated solution, two different polymers, "P3HT N2 " and "P3HT O2 " respectively, were successfully synthesized. Both produced materials were discerned by several analytical and spectroscopic techniques. UV-Vis absorption spectroscopy results showed that the radiolytic yield of 3HT oxidation in dichloromethane solvent is higher under O 2 atmosphere. Indeed, a dose of 75 kGy was needed to polymerize 10 mM in 3HT under N 2 atmosphere, meanwhile a dose of 35 kGy was sufficient to polymerize the same amount of 3HT under O 2. The average molecular weight of P3HT O2 was found higher than that of P3HT N2 as revealed by SEC chromatography analysis. Also, P3HT O2 exhibits better thermal stability than P3HT N2. ATR-FTIR spectroscopy revealed the specific presence into P3HT O2 polymers of some functional groups such as carbonyl, hydroxyl and carboxyl moieties, which clearly explains the difference between the morphological structures of P3HT N2 and P3HT O2 as highlighted by cryo-TEM, SEM and AFM microscopies. Finally, both radio-synthesized P3HT N2 and P3HT O2 polymers were found characterized by remarkably significant conductive, electronic and optical properties.
Journal of Materials Science, Jan 7, 2020
Designing organic hole transporting materials (HTMs) for stable perovskite photovoltaic devices r... more Designing organic hole transporting materials (HTMs) for stable perovskite photovoltaic devices remains a great challenge. Herein, we have prepared two small carbazole-based HTMs bearing a polymerizable double bond and one of the corresponding polymers. All compounds can be easily synthetized by a short procedure from largely available commercial products. These compounds have thermal, morphological, optical and electrochemical properties suitable for an application in perovskite solar cells. The side chains at the N-positon on the carbazole have a negligible influence on the opto-electrochemical properties. However, the thermal properties differ largely between the monomer and its corresponding polymer. While these materials have the same photovoltaic performance, the polymeric HTM led to more stable devices. This illustrates the higher thermal stability of polymeric HTM versus its corresponding monomer.
Radiation Physics and Chemistry, Jun 1, 2019
In this work, conducting polymers were synthesized for the first time in acidic aqueous solutions... more In this work, conducting polymers were synthesized for the first time in acidic aqueous solutions by means of γ-irradiation. Poly(3,4-ethylenedioxythiophene) (PEDOT) polymers were prepared under N2O atmosphere in the presence of highly concentrated hydrochloric acid (HCl) at pH ~ 0, thanks to the oxidation of 3,4ethylenedioxythiophene (EDOT) monomers by Cl2 •oxidizing radicals produced in the medium by water radiolysis. UV-Vis absorption spectroscopy was used to estimate the radiolytic yield of EDOT oxidation as well as the required dose for quantitative PEDOT preparation. After a 72-kGy irradiation, PEDOT polymers, which form dark blue suspensions, were characterized by a large absorption band at around 700 nm. Size exclusion chromatography demonstrated that these radiosynthesized PEDOT polymers contain up to 20 EDOT units. After deposition, ATR-FTIR spectroscopy and Energy-Dispersive X-ray (EDX) analysis highlighted the doping of PEDOT polymers prepared in the presence of HCl. The morphology of radiosynthesized PEDOT polymers was characterized by SEM microscopy and by high-resolution AFM-IR microscopy coupled with infrared nanospectroscopy.
A novel radiation chemistry-based methodology for the synthesis of PEDOT/Ag nanocomposites
Materials Chemistry Frontiers, 2017
A new alternative methodology based on γ-radiolysis has been successfully used for the synthesis ... more A new alternative methodology based on γ-radiolysis has been successfully used for the synthesis of nanostructured PEDOT/Ag composites.
Thin Solid Films, Aug 1, 2008
Photovoltaic characterization of planar heterojunction solar cells based on CuPc/perylene-carbazo... more Photovoltaic characterization of planar heterojunction solar cells based on CuPc/perylene-carbazole small molecule donor-acceptor couple active layer have been investigated under AM1.5 light illumination. These solar cells present better fill factors than those given by CuPc/C 60 donor-acceptor couple based cells experimented at our laboratory. This observation is assumed to result from the good homogeneity of the acceptor layer due to a planar conformation of the molecules. When the planar configuration is destroyed by Cl substitution on the perylene part of the molecule, lower device properties have been noticed.
Fast and reversible photo-responsive wettability on TiO<sub>2</sub> based hybrid surfaces
Journal of materials chemistry. A, Materials for energy and sustainability, 2015
Thin Solid Films, Aug 1, 2008
Biscarbazole and terthiophene based molecular glasses with hydrazone functional goups (named resp... more Biscarbazole and terthiophene based molecular glasses with hydrazone functional goups (named respectively 2CzMPH and 3TDPH) have been synthesized and the thermal, optical and electrochemical properties have been studied. Differential scanning calorimetry characterizations confirm the metastable amorphous properties of these molecules with glass transition temperatures at 80°C for the 3TDPH and 93°C for the 2CzMPH. Their electrochemical properties have been studied and showed the effect of the conjugated hydrazone groups on the electronic delocalization of the structures. The concept of solid state dye-sensitized solar cells using hydrazone based molecular glasses has been verified with the elaboration of a SnO 2 : F/nc-TiO 2 /Ru-dye/2CzMPH /Au devices. Under full sunlight (98 mW/cm 2 , air mass 1.5) the I-V characterization of the device give a short circuit photocurrents I sc = 0.42 mA/cm 2 , open circuit voltage V oc = 500 mV with a fill factor of 0.35.
Organic Electronics, Oct 1, 2015
A new carbazole-based polymer PEPEK varying from the previously reported PEPK by the length of th... more A new carbazole-based polymer PEPEK varying from the previously reported PEPK by the length of the spacer between the polymer backbone and the pendent carbazole moiety was investigated as polymeric host for solution-processed devices. Interestingly, if the two polymers are structurally close since the length of the alkyl chain only differs from one carbon atom, the previously reported PEPK gave higher performances than the newly synthesized PEPEK when tested as host for the wide bandgap triplet emitter FIrpic. To optimize electroluminescence performances, two device configurations were examined. On doping the emissive layer of phosphorescent organic light-emitting devices (OLEDs) at 16 wt% with FIrpic, best PEPK-based OLEDs gave an efficacy of 15.14 cd/A whereas PEPEK-based devices furnished an efficiency of 12.17 cd/A in the same conditions. To determine the origin of this unexpected behavior, the new polymer PEPEK was characterized by UV-visible absorption and luminescence spectroscopy as well as cyclic voltammetry. Thermal properties of PEPEK were also examined and compared to those of PEPK.
Thin Solid Films, Aug 1, 2014
A series of blue fluorescent Zn (II) tetradentate Schiff base complexes has been designed and syn... more A series of blue fluorescent Zn (II) tetradentate Schiff base complexes has been designed and synthesized for applications in organic light-emitting diodes. The five complexes were investigated as dopant materials or as single emitters of multilayered p-i OLEDs. White OLEDs were achieved using these compounds as dopants of 4,4′,4″tris(N-carbazolyl)triphenylamine and best devices exhibited a high quality white-light emission with remarkable CIE (Commission Internationale de l'Eclairage) coordinates (0.33, 0.34). When used as single emitters, sky-blue and blue electroluminescent devices were prepared, except with one complex that gave yellow OLEDs. Optical properties of these complexes were examined by UV-visible absorption and luminescence spectroscopy. Their electrochemical properties are also reported. These results open the route to the development of cost-effective complexes for white organic light-emitting devices applications.
Applied Catalysis B-environmental, Jul 1, 2017
Nano P3HT synthesis in hexagonal mesophases High photocatalytic activity of nano P3HT under U... more Nano P3HT synthesis in hexagonal mesophases High photocatalytic activity of nano P3HT under UV and visible light O2 •− is the main radical responsible for degradation of model pollutants The photocatalytic activity of P3HT nanostructures is much enhanced when they are supported.
Iridium(iii) soft salts from dinuclear cationic and mononuclear anionic complexes for OLED devices
Chemical Communications, 2011
Applied Catalysis B-environmental, Mar 1, 2019
in this study, we report a surfactant-mediated synthesis of ferrites (Mfe 2 o 4 : M = co, ni, cu,... more in this study, we report a surfactant-mediated synthesis of ferrites (Mfe 2 o 4 : M = co, ni, cu, Zn) using the co-precipitation-oxidation method. The band gap calculated from UV-Visible diffuse reflectance spectra were found in the range of 1.11-1.81 eV. These ferrite nanocatalysts were studied for the photocatalytic degradation of multiple organic dyes in a 32 W UV-C/H 2 o 2 system. All the four ferrites showed an excellent dye degradation rate in the range of 2.065-2.417 min −1 at neutral pH. in the optimized condition, NiF was found to degrade 89%, 92%, 93%, and 78% of methylene blue, methyl orange, bromo green, and methyl red, respectively within 1 min of UV-irradiation. A 40% TOC removal was recorded after 5 min of degradation reaction, which increased to 60% after 50 min. Mechanism elucidated by scavenger studies and fluorescence spectroscopy revealed that • oH and holes were the primary reactive radicals responsible for the degradation process. ferrite photocatalysts showed an insignificant performance loss in seven consecutive cycles. The photocatalyst was found efficient in the presence of a high concentration of salts. thus, it was concluded that these photocatalysts are highly suitable for the remediation of dye-contaminated wastewater. The ever-increasing population, coupled with rapid urbanization and industrialization, have deteriorated the quality of life. Excessive contamination of water bodies could be a severe threat to both human beings and other life forms. Organic dyes are considered as one of the major pollutants discharged into the environment by textile, printing, food, and leather industries 1. Though a large segment of these synthetic dyes is non-toxic or less toxic, their presence in water increases the oxygen demand, which in turn affects aquatic animals 2. Among the dyes consumed in industries, up to 70% belong to azo dye family (those with azo-functional group "-N = N-"). Azo dyes have genotoxic, mutagenic, and carcinogenic effects on living beings 3. Some of the azo dyes are known to be carcinogenic in the non-cleaved state, and for many of the azo dyes, their cleaved products such as benzidine are known to induce tumors 4. Conventional biological, chemical, and physical methods like adsorption 5,6 , chemical precipitation 7 , and microbial degradation 8 have been established for the remediation of dye-contaminated wastewater. The practical application of these processes suffers due to high operational cost, sludge production, or formation of secondary pollutants. For a complete or partial degradation of organic dyes (into non-toxic byproducts), degradation by adopting the photocatalytic process is one of the viable options. In recent years, advanced oxidation processes based on the generation of highly reactive hydroxyl radicals have gained momentum for the degradation of toxic organic pollutants 9. Though the Fenton process is easier to operate, it suffers badly due to a slow regeneration of Fe 2+ ions 10. Thus, the ultraviolet radiation or electrochemical method is generally coupled with the Fenton process for the regeneration of Fe 2+ ions 10,11. Unfortunately, the homogeneous photo-Fenton process has two significant drawbacks, i.e., a narrow operational pH range and formation of sludge, which increase the overall cost of the process 12. These drawbacks are motivating researchers to develop cost-effective UV-light responsive heterogeneous photocatalysts. Among numerous metal-oxide based photocatalysts developed, researchers are fixated on spinel ferrites due to their narrow band gap, magnetic property, and high stability 13. Moreover, the magnetic and optical properties
Advanced Functional Materials, May 25, 2020
Nanographene Coupled with Interfacial Pyrene Derivatives for Thermally Stable Perovskite Solar Cells
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Papers by fabrice Goubard