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Jean Roncali - One of the best experts on this subject based on the ideXlab platform.
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A New Photomechanical Molecular Switch Based on a Linear π-Conjugated System
Journal of Physical Chemistry C, 2017Co-Authors: Stéphane Lenfant, Jean Roncali, Dora Demeter, Yannick Viero, C. Krzeminski, Dominique Vuillaume, I. L. Dobra, Maiténa Oçafrain, Philippe Blanchard, C. Van DickAbstract:We report the electron-transport properties of a new photoaddressable molecular switch. The switching process relies on a new concept based on linear π-Conjugated dynamic Systems, in which the geometry and, hence, the electronic properties of an oligothiophene chain can be reversibly modified by the photochemical trans–cis isomerization of an azobenzene unit fixed in a lateral loop. Electron-transport measurements through self-assembled monolayers on gold, in contact with an eGaIn top contact, showed switching with a conductance ratio of up to 103. Ab initio calculations were used to identify the most energetically stable conformations of the molecular switch; the corresponding calculated conductances qualitatively explain the trend observed in the photoswitching experiments.
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Linearly π-Conjugated oligothiophenes as simple metal-free sensitizers for dye-sensitized solar cells
Journal of Materials Chemistry C, 2015Co-Authors: Dora Demeter, Jean Roncali, Siriporn Jungsuttiwong, Fabio Melchiorre, Paolo BiaginiAbstract:Four linear oligothiophenes containing 4, 5 and 7 thiophene rings substituted by a variable number of octyl chains attached at the beta-position of some of the thiophene rings and possessing a terminal cyanoacrylic acid anchoring group have been synthesized. Results of UV-Vis absorption spectroscopy and cyclic voltammetry show that as expected the extension of the π-Conjugated System leads to a decrease of the optical gap with an increase of the HOMO level. The four compounds have been evaluated as sensitizers in dye-sensitized solar cells (DSSCs) using a iodide/triiodide liquid electrolyte and the results are discussed in terms of the structure–property relationship with regard to the extension of the Conjugated System and the number and position of the octyl side chains using N719 as the reference System. A power conversion efficiency of ~7.30% corresponding to 90% of the value given by N719 under identical conditions has been obtained with one of the heptamers.
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Electropolymerization of three-dimensional π-Conjugated System based on 3,4-ethylenedioxythiophene (EDOT)
Electrochemistry Communications, 2008Co-Authors: Flavia Piron, Philippe Leriche, Gilles Mabon, Ion Grosu, Jean RoncaliAbstract:A 3D π-Conjugated System obtained by grafting 3,4-ethylenedioxythiophene (EDOT) on a twisted bithiophene core has been synthesized and used as precursor for electropolymerization. Preliminary investigations of its electrochemical properties shows that it can be straightforwardly electropolymerized into an electroactive Conjugated material.
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a star shaped triphenylamine π Conjugated System with internal charge transfer as donor material for hetero junction solar cells
Chemical Communications, 2006Co-Authors: Antonio Cravino, Philippe Leriche, Olivier Alévêque, Sophie Roquet, Pierre Frere, Jean RoncaliAbstract:Introduction of dicyanovinyl groups on a triphenylamine-based Conjugated System leads to an intramolecular charge transfer which extends the spectral response and raises the open-circuit voltage of the resulting hetero-junction solar cells.
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Light-Emitting Organic Solar Cells Based on a 3D Conjugated System with Internal Charge Transfer
Advanced Materials, 2006Co-Authors: Antonio Cravino, Philippe Leriche, Olivier Alévêque, Sophie Roquet, Jean RoncaliAbstract:Simple single-layered diodes based on a glass-forming triphenylamine-thienylenevinylene with internal charge transfer show a photovoltaic effect in solar light and red electroluminescence when forward biased (see figure and cover). The use of an additional layer of C60 as electron acceptor improves the photovoltaic performance without affecting the electroluminescence.
Antonio Cravino - One of the best experts on this subject based on the ideXlab platform.
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a star shaped triphenylamine π Conjugated System with internal charge transfer as donor material for hetero junction solar cells
Chemical Communications, 2006Co-Authors: Antonio Cravino, Philippe Leriche, Olivier Alévêque, Sophie Roquet, Pierre Frere, Jean RoncaliAbstract:Introduction of dicyanovinyl groups on a triphenylamine-based Conjugated System leads to an intramolecular charge transfer which extends the spectral response and raises the open-circuit voltage of the resulting hetero-junction solar cells.
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Light-Emitting Organic Solar Cells Based on a 3D Conjugated System with Internal Charge Transfer
Advanced Materials, 2006Co-Authors: Antonio Cravino, Philippe Leriche, Olivier Alévêque, Sophie Roquet, Jean RoncaliAbstract:Simple single-layered diodes based on a glass-forming triphenylamine-thienylenevinylene with internal charge transfer show a photovoltaic effect in solar light and red electroluminescence when forward biased (see figure and cover). The use of an additional layer of C60 as electron acceptor improves the photovoltaic performance without affecting the electroluminescence.
Philippe Leriche - One of the best experts on this subject based on the ideXlab platform.
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Electropolymerization of three-dimensional π-Conjugated System based on 3,4-ethylenedioxythiophene (EDOT)
Electrochemistry Communications, 2008Co-Authors: Flavia Piron, Philippe Leriche, Gilles Mabon, Ion Grosu, Jean RoncaliAbstract:A 3D π-Conjugated System obtained by grafting 3,4-ethylenedioxythiophene (EDOT) on a twisted bithiophene core has been synthesized and used as precursor for electropolymerization. Preliminary investigations of its electrochemical properties shows that it can be straightforwardly electropolymerized into an electroactive Conjugated material.
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a star shaped triphenylamine π Conjugated System with internal charge transfer as donor material for hetero junction solar cells
Chemical Communications, 2006Co-Authors: Antonio Cravino, Philippe Leriche, Olivier Alévêque, Sophie Roquet, Pierre Frere, Jean RoncaliAbstract:Introduction of dicyanovinyl groups on a triphenylamine-based Conjugated System leads to an intramolecular charge transfer which extends the spectral response and raises the open-circuit voltage of the resulting hetero-junction solar cells.
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Light-Emitting Organic Solar Cells Based on a 3D Conjugated System with Internal Charge Transfer
Advanced Materials, 2006Co-Authors: Antonio Cravino, Philippe Leriche, Olivier Alévêque, Sophie Roquet, Jean RoncaliAbstract:Simple single-layered diodes based on a glass-forming triphenylamine-thienylenevinylene with internal charge transfer show a photovoltaic effect in solar light and red electroluminescence when forward biased (see figure and cover). The use of an additional layer of C60 as electron acceptor improves the photovoltaic performance without affecting the electroluminescence.
Dora Demeter - One of the best experts on this subject based on the ideXlab platform.
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A New Photomechanical Molecular Switch Based on a Linear π-Conjugated System
Journal of Physical Chemistry C, 2017Co-Authors: Stéphane Lenfant, Jean Roncali, Dora Demeter, Yannick Viero, C. Krzeminski, Dominique Vuillaume, I. L. Dobra, Maiténa Oçafrain, Philippe Blanchard, C. Van DickAbstract:We report the electron-transport properties of a new photoaddressable molecular switch. The switching process relies on a new concept based on linear π-Conjugated dynamic Systems, in which the geometry and, hence, the electronic properties of an oligothiophene chain can be reversibly modified by the photochemical trans–cis isomerization of an azobenzene unit fixed in a lateral loop. Electron-transport measurements through self-assembled monolayers on gold, in contact with an eGaIn top contact, showed switching with a conductance ratio of up to 103. Ab initio calculations were used to identify the most energetically stable conformations of the molecular switch; the corresponding calculated conductances qualitatively explain the trend observed in the photoswitching experiments.
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Linearly π-Conjugated oligothiophenes as simple metal-free sensitizers for dye-sensitized solar cells
Journal of Materials Chemistry C, 2015Co-Authors: Dora Demeter, Jean Roncali, Siriporn Jungsuttiwong, Fabio Melchiorre, Paolo BiaginiAbstract:Four linear oligothiophenes containing 4, 5 and 7 thiophene rings substituted by a variable number of octyl chains attached at the beta-position of some of the thiophene rings and possessing a terminal cyanoacrylic acid anchoring group have been synthesized. Results of UV-Vis absorption spectroscopy and cyclic voltammetry show that as expected the extension of the π-Conjugated System leads to a decrease of the optical gap with an increase of the HOMO level. The four compounds have been evaluated as sensitizers in dye-sensitized solar cells (DSSCs) using a iodide/triiodide liquid electrolyte and the results are discussed in terms of the structure–property relationship with regard to the extension of the Conjugated System and the number and position of the octyl side chains using N719 as the reference System. A power conversion efficiency of ~7.30% corresponding to 90% of the value given by N719 under identical conditions has been obtained with one of the heptamers.
Paolo Biagini - One of the best experts on this subject based on the ideXlab platform.
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Linearly π-Conjugated oligothiophenes as simple metal-free sensitizers for dye-sensitized solar cells
Journal of Materials Chemistry C, 2015Co-Authors: Dora Demeter, Jean Roncali, Siriporn Jungsuttiwong, Fabio Melchiorre, Paolo BiaginiAbstract:Four linear oligothiophenes containing 4, 5 and 7 thiophene rings substituted by a variable number of octyl chains attached at the beta-position of some of the thiophene rings and possessing a terminal cyanoacrylic acid anchoring group have been synthesized. Results of UV-Vis absorption spectroscopy and cyclic voltammetry show that as expected the extension of the π-Conjugated System leads to a decrease of the optical gap with an increase of the HOMO level. The four compounds have been evaluated as sensitizers in dye-sensitized solar cells (DSSCs) using a iodide/triiodide liquid electrolyte and the results are discussed in terms of the structure–property relationship with regard to the extension of the Conjugated System and the number and position of the octyl side chains using N719 as the reference System. A power conversion efficiency of ~7.30% corresponding to 90% of the value given by N719 under identical conditions has been obtained with one of the heptamers.