Search

New alternating copolymers based on benzo[1,2-b:4,5-b′]dithiophene and thieno[3,4-d]thiazole derivatives have been synthesized by using different combinations of side chains and spacers in order to study their effect on the optical, electrochemical and photovoltaic properties. Optical and electrochemical characterization were performed and the resulting copolymers exhibit optical bandgaps ranging from 1.66 to 1.80 eV, HOMO energy levels between −5.19 and −5.30 eV and LUMO energy levels between −3.60 and −3.72 eV. Photovoltaic devices were fabricated and characterized after a careful optimization of the active layer fabrication by using different solvents, additives and acceptors. Following this process, PCEs up to 4.4% were obtained.

Stendhal, Merimee et les ecrivains romantiques. Le sang, la violence et la mort est un ouvrage comportant l’ensemble des actes d’un colloque de Paris-INHA Sorbonne s’etant deroule les 5 et 6 octobre 2007. Les etudes, reunies et presentees par Michel Arrous, a qui l’on doit notamment de nombreux articles du Dictionnaire de Stendhal mais aussi la co-organisation du recent colloque «Stendhal et le recit bref» (7 et 8 fevrier 2015), sont au nombre de dix-sept. Elles se focalisent pour la majeure ...

We report the synthesis of new push-pull conjugated polymers for bulk heterojunction solar cells based on benzo[1,2-b:4,5-b′]dithiophene (push) and thieno[3,4-d]thiazole (TTz) (pull) derivatives. Stille polycondensation between distannyl-BDT derivatives with 4,6-dibromo-2-octylthieno[3,4-d]thiazole led to two alternating copolymers, namely PBDTTTz-1 and PBDTTTz-2, which have a bandgap of 1.8 and 1.7 eV, respectively. Both copolymers are stable in air with HOMO energy level of -5.3 eV for PBDTTTz-1 and -5.4 eV for PBDTTTz-2. Both copolymers have been tested in bulk heterojunction solar cells, and preliminary results (without any optimization process) show promising power conversion efficiency of 1.4% for PBDTTTz-1 and 1.7% for PBDTTTz-2. © 2011 American Chemical Society.

Dans son ouvrage Le Heros monstrueux, une lecture psychanalytique du personnage romanesque de Stendhal, Mamadou Ould Dahmed, maitre de conferences a la Faculte des Lettres de Nouakchott, propose une etude relativement originale de l’œuvre stendhalienne. En effet, alors meme que les recherches melant psychanalyse et litterature semblent peu a peu tomber en desuetude, Mamadou Ould Dahmed choisit d’en faire la pierre de touche de son ouvrage. En se focalisant principalement sur quatre romans ste...

The synthesis and characterization of new heterofluorene derivatives based on germanium are described. These germafluorene monomers have been polymerized with different aromatic comonomers. The resulting homopolymers and alternating copolymers have been characterized by size exclusion chromatography, thermal analyses (TGA and DSC), UV-vis-NIR absorption spectroscopy, X-ray diffraction, and cyclic voltammetry. These homopolymers and copolymers are air-stable and present bandgaps ranging from 3.0 to 1.6 eV. Some copolymers were tested in field-effect transistors (FETs) and bulk heterojunction photovoltaic cells (PCs). Best results in FETs were obtained with poly[2,7-(9,9-di-n-butylgermafluorene)-alt 3,6-bis(thiophen-5-yl)-2,5-dioctylpyrrolo[3,4-]pyrrole-1,4-dione], which shows a hole mobility up to 0.04 cm2 (V 3 s)-1 with an Ion/Ioff ratio of 1.0_106. For photovoltaic applications, the best results were obtained with poly[2,7-(9,9-di-n-octylgermafluorene)-alt-5,5-(40,70-di-2-thienyl-20,10,30-benzothiadiazole)] with a power conversion efficiency (PCE) of 2.8%.

A series of new dithieno[3,2-b:2′,3′-d]germole copolymers have been synthesized and characterized. The dithienogermole unit has been polymerized with different aromatic comonomers such as the benzothiadiazole (PGe1-C8 and PGe1-EH) and thieno[3,4-c]pyrrole-4,6-dione (PGe2). Suzuki and Stille coupling polymerizations under various conditions have been utilized. The polymers were then characterized by size-exclusion chromatography and thermal analyses (TGA, DSC), and their optical and electronic properties were investigated by UV-vis absorption spectroscopy and cyclic voltammetry. These low bandgap polymers (1.3-1.7 eV) have also been tested for photovoltaic applications; the best result was achieved with polymer PGe2, which shows a power conversion efficiency of 4.1%. © 2011 American Chemical Society.

New alternating copolymers based on thieno[3,4-d]thiazole (TTz) derivatives were synthesized by Stille, Suzuki or direct (hetero)arylation polycondensation (DHAP) reactions using either benzodithiophene (BDT), dithienosilole (DTS), thieno[3,4-c]pyrrole-4,6-dione (TPD), diketopyrrolopyrrole-1,4-dione (DPP) or isoindigo units as comonomers. In particular, the direct hetero(arylation) polycondensation reaction has been shown to be a very interesting tool for a more efficient and economical access to new conjugated polymers. Modifications of the TTz moiety and of the polymer backbone show that it is possible to efficiently modulate the HOMO and LUMO energy levels of TTz-based copolymers. These conjugated polymers exhibit bandgaps between 1.07 and 1.82 eV with HOMO energy levels ranging from −5.06 to −5.48 eV and LUMO energy levels ranging from −3.61 to −4.02 eV.