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New low bandgap conjugated polymer derived from 2, 7‐carbazole and 5, 6‐bis(octyloxy)‐4, 7‐di(thiophen‐2‐yl) benzothiadiazole: Synthesis and photovoltaic properties
Author(s) -
Ding Ping,
Chu ChengChe,
Zou Yingping,
Xiao Dequan,
Pan Chunyue,
Hsu ChainShu
Publication year - 2011
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.34439
Subject(s) - materials science , conjugated system , band gap , polymer , polymer solar cell , copolymer , carbazole , solubility , open circuit voltage , polymer chemistry , energy conversion efficiency , polymerization , thermal stability , short circuit , chemical engineering , chemistry , photochemistry , optoelectronics , voltage , composite material , physics , quantum mechanics , engineering
To develop conjugated polymers with low bandgap, deep HOMO level, and good solubility, a new conjugated alternating copolymer PC‐DODTBT based on N ‐9′‐heptadecanyl‐2,7‐carbazole and 5, 6‐bis(octyloxy)‐4,7‐di(thiophen‐2‐yl)benzothiadiazole was synthesized by Suzuki cross‐coupling polymerization reaction. The polymer reveals excellent solubility and thermal stability with the decomposition temperature (5% weight loss) of 327°C. The HOMO level of PC‐DODTBT is ‐5.11 eV, indicating that the polymer has relatively deep HOMO level. The hole mobility of PC‐DODTBT as deduced from SCLC method was found to be 2.03 × 10 −4 cm 2 /Versus Polymer solar cells (PSCs) based on the blends of PC‐DODTBT and [6,6]‐phenyl‐C 71 ‐butyric acid methyl ester (PC 71 BM) with a weight ratio of 1:2.5 were fabricated. Under AM 1.5 (AM, air mass), 100 mW/cm −2 illumination, the devices were found to exhibit an open‐circuit voltage ( V oc ) of 0.73 V, short‐circuit current density ( J sc ) of 5.63 mA/cm −2 , and a power conversion efficiency (PCE) of 1.44%. This photovoltaic performance indicates that the copolymer is promising for polymer solar cells applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011