Michèle Chevrier - Academia.edu (original) (raw)
Papers by Michèle Chevrier
Among renewable energies, the sunlight has by far the highest theoretical potential to meet the w... more Among renewable energies, the sunlight has by far the highest theoretical potential to meet the worldwide need in energy. Photovoltaic devices are thus currently the subject of intense research for low-cost conversion of sunlight into electrical power. In particular, organic photovoltaics have emerged as an interesting alternative to produce electricity due to their low manufacturing cost compared to silicon solar cells, their mechanical flexibility and the versatility of the possible chemical structures. In this dissertation, we focused our research on the development of new organic pi-conjugated materials for organic solar cells applications. Two types of solar cells have been studied during this work: bulk heterojunction and dye-sensitized solar cells. The charge transfer leading to the photocurrent is usually based on (i) a polymer donor and a fullerene acceptor in BHJ solar cells, such as the widely studied poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ...
Journal of Materials Chemistry, 2015
Interfacial engineering is poised to play a key role in delivering solution-processable organic s... more Interfacial engineering is poised to play a key role in delivering solution-processable organic solar cells that simultaneously feature low cost and high efficiency. Here, we report the strategic design, synthesis and characterisation of phosphonium-functionalised polythiophene homo-(P3HTPMe3) and diblock (P3HT-b-P3HTPMe3) conjugated polyelectrolytes (CPEs) coupled with either bromide (Br-) or dodecylsulfate (DS-) surfactant counterions, for application as cathodic interlayers in polymer solar cells. The counterion is shown to have a pronounced effect on the properties of the CPEs in solution. Optical studies revealed that the bulkier DS-counterion hinders interchain interactions more effectively, leading to a moderate blue-shift in the absorption and emission maxima. Similarly, small-angle neutron scattering (SANS) studies also indicated that the solution structures, solvent content, and therefore hydrophobicity, were extremely dependent on both the CPE structure and counterion. The effect of the CPE structure on the thermal properties of the CPE-surfactant complexes was also investigated by Rapid Heat-Cool calorimetry (RHC) measurements. CPE-DS complexes were subsequently employed as cathodic interfacial layers and shown to boost the efficiency of PBDTTPD:PC71BM solar cells, leading to enhanced power conversion efficiencies of 8.65% and 8.78% (on average) for P3HTPMe3,DS and P3HT-b-P3HTPMe3,DS, respectively. These values are significantly higher (~20%) than those for the corresponding device incorporating a Ca interfacial layer (7.18%), which is attributed to an increase in short-circuit current density. Atomic force microscopy studies revealed distinctions in the adhesion efficiencies of the CPE-DS complexes to the photoactive layer, which is attributed to differences in the relative hydrophobicity of the CPEs in the deposition solution. 10 and water/alcohol-soluble conjugated polymers 11 have been used for this purpose. Conjugated polyelectrolytes (CPEs) in particular have been widely studied as interfacial charge transport and extraction layer materials. 11,12 This additional layer induces the formation and alignment of an interfacial dipole leading to a reduced work function potential of the cathode.
Michèle Chevrier, Riccardo Di Ciuccio, Olivier Coulembier, Philippe Dubois, Sebastien Richeter, A... more Michèle Chevrier, Riccardo Di Ciuccio, Olivier Coulembier, Philippe Dubois, Sebastien Richeter, Ahmad Mehdi and Sébastien Clément Functionalization of P3HT-Based Hybrid Materials for Photovoltaic Applications, Novel Nanoscale Hybrid Materials, Éditions Bhanu P. S. Chauhan, , 2018. Fatima Abi-Ghaida, Sébastien Clément and Ahmad Mehdi Heterogenized Catalysis on Metals Impregnated Mesoporous Silica, Novel Nanoscale Hybrid Materials, Éditions Bhanu P. S. Chauhan, , 2018.
Le developpement des energies renouvelables est aujourd’hui devenu un enjeu mondial majeur comme ... more Le developpement des energies renouvelables est aujourd’hui devenu un enjeu mondial majeur comme alternative aux energies fossiles dans la production d'energie. Parmi elles, l’energie solaire est consideree comme la source la plus prometteuse, permettant de couvrir l’ensemble des besoins energetiques lies a l’activite humaine. Les cellules photovoltaiques les plus performantes aujourd’hui, entre 16 et 18 % en modules, sont composees de silicium, un semi-conducteur inorganique. Cependant, leur cout de production eleve a necessite le developpement de materiaux alternatifs moins couteux. Parmi les voies explorees, les cellules solaires organiques ont emerge comme une alternative prometteuse pour produire l’electricite a faible cout. Le sujet de cette these s’integre dans ce contexte de recherche. Deux types de cellules solaires ont ete etudies : les cellules a heterojonction en volume (BHJ) et sensibilisees au colorant (DSSCs). Le courant photogenere repose generalement (i) dans le...
Polymer International
Phosphonium-based polythiophene conjugated polyelectrolytes (CPEs) with three different counterio... more Phosphonium-based polythiophene conjugated polyelectrolytes (CPEs) with three different counterions (dodecylsulfate (DS), octylsulfate (OS) and perfluorooctylsulfonate (PFOS)) are synthesized to determine how the nature of the counterion affects the thermal properties, the self-assembly in thin films and the performance as cathode interfacial layer in polymer solar cells (PSCs). The counterion has a significant effect on the thermal properties of the CPEs, affecting both their glass transition and crystalline behavior. Grazing-incidence wide-angle Xray scattering (GIWAXS) studies also indicate that changing the nature of the counterion influences the microstructural organization in thin films (face-on vs. edge-on orientation). The affinity of the CPEs with the underlying photoactive layer in PSCs is highly correlated with the counterion species. Finally, in addition to an increase of the power conversion efficiency of ~15% when using these CPEs as cathode interfacial layers in PSCs, a higher device stability is noted, as compared to a reference device with a calcium interlayer.
Molecules
Chlorophyll a derivatives were integrated in “all solid-state” dye sensitized solar cells (DSSCs)... more Chlorophyll a derivatives were integrated in “all solid-state” dye sensitized solar cells (DSSCs) with a mesoporous TiO2 electrode and 2′,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene as the hole-transport material. Despite modest power conversion efficiencies (PCEs) between 0.26% and 0.55% achieved for these chlorin dyes, a systematic investigation was carried out in order to elucidate their main limitations. To provide a comprehensive understanding of the parameters (structure, nature of the anchoring group, adsorption …) and their relationship with the PCEs, density functional theory (DFT) calculations, optical and photovoltaic studies and electron paramagnetic resonance analysis exploiting the 4-carboxy-TEMPO spin probe were combined. The recombination kinetics, the frontier molecular orbitals of these DSSCs and the adsorption efficiency onto the TiO2 surface were found to be the key parameters that govern their photovoltaic response.
Synthetic Metals
A poly(3-hexylthiophene)-block-perfluoropolyether-block-poly(3-hexylthiophene) (P3HT-b-PFPE-b-P3H... more A poly(3-hexylthiophene)-block-perfluoropolyether-block-poly(3-hexylthiophene) (P3HT-b-PFPE-b-P3HT) triblock copolymer was synthesized by copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) in 95% yield. The copolymer was unequivocally characterized by size exclusion chromatography reaching 27 000 g mol −1 and nuclear magnetic resonance (NMR). As expected, diffusion-ordered spectroscopy NMR experiment revealed a lower diffusion coefficient (2.56 × 10-10 m 2 s −1) for the P3HT-b-PFPE-b-P3HT triblock copolymer than the ethynyl end-functionalized P3HT (2.83 × 10-10 m 2 s −1). Such a triblock copolymer exhibits i) a good thermal stability with no significant weight loss until 320°C under air, ii) a glass transition of-50°C due to the soft PFPE segment and iii) a melting peak arising from P3HT at 236°C. The UV-vis absorption spectrum exhibits a similar absorption profile to that of pure P3HT with a vibronic structure. Analysis of terpolymer thin films by atomic force microscopy imaging and grazing incidence wide-angle X-ray scattering reveals the formation of P3HT crystallites and an "edge-on" orientation of the polymer chains towards the substrate. Preliminary photovoltaic studies on blends of this triblock copolymer combined with a fullerene derivative indicate that the devices using P3HT-b-PFPE-b-P3HT show an almost similar power conversion efficiency to commercial P3HT. Block copolymers are interesting materials to generate suitable
Nanoscale, Jan 16, 2017
Targeted control of the aggregation, morphology and optical properties of conjugated polymers is ... more Targeted control of the aggregation, morphology and optical properties of conjugated polymers is critical for the development of high performance optoelectronic devices. Here, self-assembly approaches are used to strategically manipulate the order, conformation and spatial distribution of conjugated polymers in solution and subsequently prepared thin films. The supramolecular complex organisation of phosphonium-functionalised homo- (P3HTPMe3) and diblock (P3HT-b-P3HTPMe3) ionic conjugated polythiophenes upon solvent-mediation and co-assembly with oppositely charged surfactants is investigated. UV/Vis absorption and photoluminescence spectroscopies, small-angle neutron scattering (SANS), cryo-transmission electron microscopy (cryo-TEM) and atomic force microscopy (AFM) are used to probe the organisation and photophysical response of the aggregates formed. Subtle differences in the surfactant mole fraction and structure, as well as the solvent polarity, yield differences in the nature...
Organic Photovoltaics XVII
Organic photovoltaics (OPV) show strong potential for a number of renewable energy applications b... more Organic photovoltaics (OPV) show strong potential for a number of renewable energy applications because of some specifically appealing features (light weight, flexibility, color, …). Over the past decade, the power conversion efficiencies of organic solar cells have strongly risen to values surpassing the 10% threshold, mainly due to strong efforts in chemical engineering of the photoactive components, architectural device optimization and acquisition of fundamental insights in the underlying device physics. As part of the device optimization, the use of conjugated polyelectrolyte (CPE) interfacial layers has been introduced as a popular and powerful way to boost the inherent I-V characteristics. In the presented work, we applied impedance spectroscopy to probe the dielectric permittivity of a series of polythiophene-based CPE interlayer materials as a means to postulate design rules toward novel generation interfacial layers. The presence of ionic pendant groups grants the formation of a capacitive double layer, boosting the charge extraction and device efficiency. A counteracting effect is that the material’s affinity with respect to the underlying photoactive layer diminishes. To enhance the interlayer-photoactive layer compatibility, copolymer structures containing a certain amount of non-ionic side chains are found to be beneficial.
Synthetic Metals
All solid-state dye-sensitized solar cells (ss-DSSCs) based on the reference D102 organic dye and... more All solid-state dye-sensitized solar cells (ss-DSSCs) based on the reference D102 organic dye and using poly(3-hexylthiophene) (P3HT) as hole transporting material were fabricated and compared to the most used 2,2 0 ,7,7 0-tetrakis-(N,N-dip -methoxyphenylamine)-9,9 0-spirobifluorene (spiro-OMeTAD). Power conversion efficiency of 4.78% was reached with P3HT vs. 3.99% with spiro-OMeTAD, which emphasizes that polythiophene derivatives remain serious alternatives to spiro-OMeTAD for efficient and low-cost photovoltaic energy conversion. Here, P3HT combining high regioregularity, medium-range molecular weight and narrow dispersity was targeted. The ability of those P3HT chains to form semicrystalline domains upon annealing leads to improved hole mobility, photocurrent collection and thus, device performance.
ACS applied materials & interfaces, Jan 3, 2016
Conjugated polyelectrolyte (CPE) interfacial layers present a powerful way to boost the I-V chara... more Conjugated polyelectrolyte (CPE) interfacial layers present a powerful way to boost the I-V characteristics of organic photovoltaics. Nevertheless, clear guidelines with respect to the structure of high-performance interlayers are still lacking. In this work, impedance spectroscopy is applied to probe the dielectric permittivity of a series of polythiophene-based CPEs. The presence of ionic pendant groups grants the formation of a capacitive double layer, boosting the charge extraction and device efficiency. A counteracting effect is the diminishing affinity with the underlying photoactive layer. To balance these two effects, we found copolymer structures containing nonionic side chains to be beneficial.
J. Mater. Chem. A, 2015
Conjugated polyelectrolyte–surfactant cathodic interface layers lead to improved power conversion... more Conjugated polyelectrolyte–surfactant cathodic interface layers lead to improved power conversion efficiencies in organic solar cells.
Chem. Commun., 2015
Poly(3-hexylthiophene)s end-functionalized with π-extended porphyrins show a broad absorption pro... more Poly(3-hexylthiophene)s end-functionalized with π-extended porphyrins show a broad absorption profile up to 700 nm and a fibrillar microstructure tuned by the porphyrin molar ratio.
![Research paper thumbnail of The structure–property relationship study of electron-deficient dihydroindeno[2,1-b]fluorene derivatives for n-type organic field effect transistors](https://attachments.academia-assets.com/81831386/thumbnails/1.jpg)
](J. Mater. Chem. C, 2015
A bridged syn triphenylene derivative functionalized with dicyanovinylene units (2,1-b)-IF(C(CN)... more A bridged syn triphenylene derivative functionalized with dicyanovinylene units (2,1-b)-IF(C(CN)2)2 has been synthesized, characterized and successfully used as an active layer in n-channel OFETs. Pseudo CMOS inverters made of n-type (2,1-b)-IF(C(CN)2)2 -based OFETs have been fabricated.
Polymer Chemistry, 2014
The optical and thermal properties and solvent-dependent assembly of all-conjugated cationic copo... more The optical and thermal properties and solvent-dependent assembly of all-conjugated cationic copolythiophene block copolyelectrolytes are investigated.
Macromolecular Chemistry and Physics, 2015
Conjugated poly(3-hexylthiophene) copolymer derivatives containing 10% appended porphyrin moietie... more Conjugated poly(3-hexylthiophene) copolymer derivatives containing 10% appended porphyrin moieties are prepared using a supramolecular approach toward applications in organic electronics. The self-assembled polythiophene-porphyrin copolymers are synthesized by coordination of the porphyrinato central zinc ions to the imidazole-functionalized polythiophene side chains. Evidence for the self-assembly process is provided by 1 H NMR spectroscopy, single crystal X-ray diffraction, and optical absorption studies on model compounds. The polythiopheneporphyrin copolymers show an extended absorption window in the region of 420-650 nm due to the contribution of the porphyrin. Photoluminescence studies indicate concentrationdependent energy transfer from P3HT to the porphyrin. Preliminary photovoltaic studies are performed by combining the polythiophene-porphyrin copolymers with PC 61 BM in the photo active layer of bulk heterojunction organic solar cells.
Among renewable energies, the sunlight has by far the highest theoretical potential to meet the w... more Among renewable energies, the sunlight has by far the highest theoretical potential to meet the worldwide need in energy. Photovoltaic devices are thus currently the subject of intense research for low-cost conversion of sunlight into electrical power. In particular, organic photovoltaics have emerged as an interesting alternative to produce electricity due to their low manufacturing cost compared to silicon solar cells, their mechanical flexibility and the versatility of the possible chemical structures. In this dissertation, we focused our research on the development of new organic pi-conjugated materials for organic solar cells applications. Two types of solar cells have been studied during this work: bulk heterojunction and dye-sensitized solar cells. The charge transfer leading to the photocurrent is usually based on (i) a polymer donor and a fullerene acceptor in BHJ solar cells, such as the widely studied poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ...
Journal of Materials Chemistry, 2015
Interfacial engineering is poised to play a key role in delivering solution-processable organic s... more Interfacial engineering is poised to play a key role in delivering solution-processable organic solar cells that simultaneously feature low cost and high efficiency. Here, we report the strategic design, synthesis and characterisation of phosphonium-functionalised polythiophene homo-(P3HTPMe3) and diblock (P3HT-b-P3HTPMe3) conjugated polyelectrolytes (CPEs) coupled with either bromide (Br-) or dodecylsulfate (DS-) surfactant counterions, for application as cathodic interlayers in polymer solar cells. The counterion is shown to have a pronounced effect on the properties of the CPEs in solution. Optical studies revealed that the bulkier DS-counterion hinders interchain interactions more effectively, leading to a moderate blue-shift in the absorption and emission maxima. Similarly, small-angle neutron scattering (SANS) studies also indicated that the solution structures, solvent content, and therefore hydrophobicity, were extremely dependent on both the CPE structure and counterion. The effect of the CPE structure on the thermal properties of the CPE-surfactant complexes was also investigated by Rapid Heat-Cool calorimetry (RHC) measurements. CPE-DS complexes were subsequently employed as cathodic interfacial layers and shown to boost the efficiency of PBDTTPD:PC71BM solar cells, leading to enhanced power conversion efficiencies of 8.65% and 8.78% (on average) for P3HTPMe3,DS and P3HT-b-P3HTPMe3,DS, respectively. These values are significantly higher (~20%) than those for the corresponding device incorporating a Ca interfacial layer (7.18%), which is attributed to an increase in short-circuit current density. Atomic force microscopy studies revealed distinctions in the adhesion efficiencies of the CPE-DS complexes to the photoactive layer, which is attributed to differences in the relative hydrophobicity of the CPEs in the deposition solution. 10 and water/alcohol-soluble conjugated polymers 11 have been used for this purpose. Conjugated polyelectrolytes (CPEs) in particular have been widely studied as interfacial charge transport and extraction layer materials. 11,12 This additional layer induces the formation and alignment of an interfacial dipole leading to a reduced work function potential of the cathode.
Michèle Chevrier, Riccardo Di Ciuccio, Olivier Coulembier, Philippe Dubois, Sebastien Richeter, A... more Michèle Chevrier, Riccardo Di Ciuccio, Olivier Coulembier, Philippe Dubois, Sebastien Richeter, Ahmad Mehdi and Sébastien Clément Functionalization of P3HT-Based Hybrid Materials for Photovoltaic Applications, Novel Nanoscale Hybrid Materials, Éditions Bhanu P. S. Chauhan, , 2018. Fatima Abi-Ghaida, Sébastien Clément and Ahmad Mehdi Heterogenized Catalysis on Metals Impregnated Mesoporous Silica, Novel Nanoscale Hybrid Materials, Éditions Bhanu P. S. Chauhan, , 2018.
Le developpement des energies renouvelables est aujourd’hui devenu un enjeu mondial majeur comme ... more Le developpement des energies renouvelables est aujourd’hui devenu un enjeu mondial majeur comme alternative aux energies fossiles dans la production d'energie. Parmi elles, l’energie solaire est consideree comme la source la plus prometteuse, permettant de couvrir l’ensemble des besoins energetiques lies a l’activite humaine. Les cellules photovoltaiques les plus performantes aujourd’hui, entre 16 et 18 % en modules, sont composees de silicium, un semi-conducteur inorganique. Cependant, leur cout de production eleve a necessite le developpement de materiaux alternatifs moins couteux. Parmi les voies explorees, les cellules solaires organiques ont emerge comme une alternative prometteuse pour produire l’electricite a faible cout. Le sujet de cette these s’integre dans ce contexte de recherche. Deux types de cellules solaires ont ete etudies : les cellules a heterojonction en volume (BHJ) et sensibilisees au colorant (DSSCs). Le courant photogenere repose generalement (i) dans le...
Polymer International
Phosphonium-based polythiophene conjugated polyelectrolytes (CPEs) with three different counterio... more Phosphonium-based polythiophene conjugated polyelectrolytes (CPEs) with three different counterions (dodecylsulfate (DS), octylsulfate (OS) and perfluorooctylsulfonate (PFOS)) are synthesized to determine how the nature of the counterion affects the thermal properties, the self-assembly in thin films and the performance as cathode interfacial layer in polymer solar cells (PSCs). The counterion has a significant effect on the thermal properties of the CPEs, affecting both their glass transition and crystalline behavior. Grazing-incidence wide-angle Xray scattering (GIWAXS) studies also indicate that changing the nature of the counterion influences the microstructural organization in thin films (face-on vs. edge-on orientation). The affinity of the CPEs with the underlying photoactive layer in PSCs is highly correlated with the counterion species. Finally, in addition to an increase of the power conversion efficiency of ~15% when using these CPEs as cathode interfacial layers in PSCs, a higher device stability is noted, as compared to a reference device with a calcium interlayer.
Molecules
Chlorophyll a derivatives were integrated in “all solid-state” dye sensitized solar cells (DSSCs)... more Chlorophyll a derivatives were integrated in “all solid-state” dye sensitized solar cells (DSSCs) with a mesoporous TiO2 electrode and 2′,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene as the hole-transport material. Despite modest power conversion efficiencies (PCEs) between 0.26% and 0.55% achieved for these chlorin dyes, a systematic investigation was carried out in order to elucidate their main limitations. To provide a comprehensive understanding of the parameters (structure, nature of the anchoring group, adsorption …) and their relationship with the PCEs, density functional theory (DFT) calculations, optical and photovoltaic studies and electron paramagnetic resonance analysis exploiting the 4-carboxy-TEMPO spin probe were combined. The recombination kinetics, the frontier molecular orbitals of these DSSCs and the adsorption efficiency onto the TiO2 surface were found to be the key parameters that govern their photovoltaic response.
Synthetic Metals
A poly(3-hexylthiophene)-block-perfluoropolyether-block-poly(3-hexylthiophene) (P3HT-b-PFPE-b-P3H... more A poly(3-hexylthiophene)-block-perfluoropolyether-block-poly(3-hexylthiophene) (P3HT-b-PFPE-b-P3HT) triblock copolymer was synthesized by copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) in 95% yield. The copolymer was unequivocally characterized by size exclusion chromatography reaching 27 000 g mol −1 and nuclear magnetic resonance (NMR). As expected, diffusion-ordered spectroscopy NMR experiment revealed a lower diffusion coefficient (2.56 × 10-10 m 2 s −1) for the P3HT-b-PFPE-b-P3HT triblock copolymer than the ethynyl end-functionalized P3HT (2.83 × 10-10 m 2 s −1). Such a triblock copolymer exhibits i) a good thermal stability with no significant weight loss until 320°C under air, ii) a glass transition of-50°C due to the soft PFPE segment and iii) a melting peak arising from P3HT at 236°C. The UV-vis absorption spectrum exhibits a similar absorption profile to that of pure P3HT with a vibronic structure. Analysis of terpolymer thin films by atomic force microscopy imaging and grazing incidence wide-angle X-ray scattering reveals the formation of P3HT crystallites and an "edge-on" orientation of the polymer chains towards the substrate. Preliminary photovoltaic studies on blends of this triblock copolymer combined with a fullerene derivative indicate that the devices using P3HT-b-PFPE-b-P3HT show an almost similar power conversion efficiency to commercial P3HT. Block copolymers are interesting materials to generate suitable
Nanoscale, Jan 16, 2017
Targeted control of the aggregation, morphology and optical properties of conjugated polymers is ... more Targeted control of the aggregation, morphology and optical properties of conjugated polymers is critical for the development of high performance optoelectronic devices. Here, self-assembly approaches are used to strategically manipulate the order, conformation and spatial distribution of conjugated polymers in solution and subsequently prepared thin films. The supramolecular complex organisation of phosphonium-functionalised homo- (P3HTPMe3) and diblock (P3HT-b-P3HTPMe3) ionic conjugated polythiophenes upon solvent-mediation and co-assembly with oppositely charged surfactants is investigated. UV/Vis absorption and photoluminescence spectroscopies, small-angle neutron scattering (SANS), cryo-transmission electron microscopy (cryo-TEM) and atomic force microscopy (AFM) are used to probe the organisation and photophysical response of the aggregates formed. Subtle differences in the surfactant mole fraction and structure, as well as the solvent polarity, yield differences in the nature...
Organic Photovoltaics XVII
Organic photovoltaics (OPV) show strong potential for a number of renewable energy applications b... more Organic photovoltaics (OPV) show strong potential for a number of renewable energy applications because of some specifically appealing features (light weight, flexibility, color, …). Over the past decade, the power conversion efficiencies of organic solar cells have strongly risen to values surpassing the 10% threshold, mainly due to strong efforts in chemical engineering of the photoactive components, architectural device optimization and acquisition of fundamental insights in the underlying device physics. As part of the device optimization, the use of conjugated polyelectrolyte (CPE) interfacial layers has been introduced as a popular and powerful way to boost the inherent I-V characteristics. In the presented work, we applied impedance spectroscopy to probe the dielectric permittivity of a series of polythiophene-based CPE interlayer materials as a means to postulate design rules toward novel generation interfacial layers. The presence of ionic pendant groups grants the formation of a capacitive double layer, boosting the charge extraction and device efficiency. A counteracting effect is that the material’s affinity with respect to the underlying photoactive layer diminishes. To enhance the interlayer-photoactive layer compatibility, copolymer structures containing a certain amount of non-ionic side chains are found to be beneficial.
Synthetic Metals
All solid-state dye-sensitized solar cells (ss-DSSCs) based on the reference D102 organic dye and... more All solid-state dye-sensitized solar cells (ss-DSSCs) based on the reference D102 organic dye and using poly(3-hexylthiophene) (P3HT) as hole transporting material were fabricated and compared to the most used 2,2 0 ,7,7 0-tetrakis-(N,N-dip -methoxyphenylamine)-9,9 0-spirobifluorene (spiro-OMeTAD). Power conversion efficiency of 4.78% was reached with P3HT vs. 3.99% with spiro-OMeTAD, which emphasizes that polythiophene derivatives remain serious alternatives to spiro-OMeTAD for efficient and low-cost photovoltaic energy conversion. Here, P3HT combining high regioregularity, medium-range molecular weight and narrow dispersity was targeted. The ability of those P3HT chains to form semicrystalline domains upon annealing leads to improved hole mobility, photocurrent collection and thus, device performance.
ACS applied materials & interfaces, Jan 3, 2016
Conjugated polyelectrolyte (CPE) interfacial layers present a powerful way to boost the I-V chara... more Conjugated polyelectrolyte (CPE) interfacial layers present a powerful way to boost the I-V characteristics of organic photovoltaics. Nevertheless, clear guidelines with respect to the structure of high-performance interlayers are still lacking. In this work, impedance spectroscopy is applied to probe the dielectric permittivity of a series of polythiophene-based CPEs. The presence of ionic pendant groups grants the formation of a capacitive double layer, boosting the charge extraction and device efficiency. A counteracting effect is the diminishing affinity with the underlying photoactive layer. To balance these two effects, we found copolymer structures containing nonionic side chains to be beneficial.
J. Mater. Chem. A, 2015
Conjugated polyelectrolyte–surfactant cathodic interface layers lead to improved power conversion... more Conjugated polyelectrolyte–surfactant cathodic interface layers lead to improved power conversion efficiencies in organic solar cells.
Chem. Commun., 2015
Poly(3-hexylthiophene)s end-functionalized with π-extended porphyrins show a broad absorption pro... more Poly(3-hexylthiophene)s end-functionalized with π-extended porphyrins show a broad absorption profile up to 700 nm and a fibrillar microstructure tuned by the porphyrin molar ratio.
J. Mater. Chem. C, 2015
A bridged syn triphenylene derivative functionalized with dicyanovinylene units (2,1-b)-IF(C(CN)... more A bridged syn triphenylene derivative functionalized with dicyanovinylene units (2,1-b)-IF(C(CN)2)2 has been synthesized, characterized and successfully used as an active layer in n-channel OFETs. Pseudo CMOS inverters made of n-type (2,1-b)-IF(C(CN)2)2 -based OFETs have been fabricated.
Polymer Chemistry, 2014
The optical and thermal properties and solvent-dependent assembly of all-conjugated cationic copo... more The optical and thermal properties and solvent-dependent assembly of all-conjugated cationic copolythiophene block copolyelectrolytes are investigated.
Macromolecular Chemistry and Physics, 2015
Conjugated poly(3-hexylthiophene) copolymer derivatives containing 10% appended porphyrin moietie... more Conjugated poly(3-hexylthiophene) copolymer derivatives containing 10% appended porphyrin moieties are prepared using a supramolecular approach toward applications in organic electronics. The self-assembled polythiophene-porphyrin copolymers are synthesized by coordination of the porphyrinato central zinc ions to the imidazole-functionalized polythiophene side chains. Evidence for the self-assembly process is provided by 1 H NMR spectroscopy, single crystal X-ray diffraction, and optical absorption studies on model compounds. The polythiopheneporphyrin copolymers show an extended absorption window in the region of 420-650 nm due to the contribution of the porphyrin. Photoluminescence studies indicate concentrationdependent energy transfer from P3HT to the porphyrin. Preliminary photovoltaic studies are performed by combining the polythiophene-porphyrin copolymers with PC 61 BM in the photo active layer of bulk heterojunction organic solar cells.