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New Alternating Copolymers of 3,6‐Carbazoles and Dithienylbenzothiadiazoles: Synthesis, Characterization, and Application in Photovoltaics
Author(s) -
Berton Nicolas,
Ottone Chiara,
Labet Vanessa,
de Bettignies Rémi,
Bailly Séverine,
Grand André,
Morell Christophe,
Sadki Saïd,
Chandezon Frédéric
Publication year - 2011
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201100209
Subject(s) - band gap , copolymer , materials science , thiophene , photovoltaics , carbazole , steric effects , organic solar cell , polymer chemistry , photochemistry , photovoltaic system , chemical engineering , optoelectronics , chemistry , polymer , organic chemistry , ecology , composite material , biology , engineering
Three new low‐bandgap copolymers containing 3,6‐linked carbazole units are synthesized and characterized using a combination of spectroscopic and electrochemical techniques and DFT calculations. The electron‐withdrawing effect of the BTD units leads to a significant decrease of the optical bandgap from 2.59 eV for PBTC to 1.81 eV for PCDTBT, whereas pendant octyl chains on the thiophene ring lead to an increase of the gap to 2.05 eV for PCDOTBT due to steric hindrance. PBTC:PCBM photovoltaic devices exhibit a PCE of 0.35% with an EQE reaching 35% in the blue region of the solar spectrum whereas PCDTBT:PCBM blends are efficient over a wider spectral range due to the lower bandgap of PCDTBT.