New Conjugated Copolymers Based on Benzo[1,2-b; 3,4-b′]dithiophene and Derivatives of Benzo[g]quinoxaline for Bulk Heterojunction Solar Cells

A series of new low-band gap copolymers based on dioctyloxybenzo[1,2-b;3,4-b'] dithiophene and bis(2-thienyl)-2,3-diphenylbenzo[g]quinoxaline monomers have been synthesized via a Stille reaction. The effect of different functional groups attached to bis(2-thienyl)-2,3-diphenylbenzo[g]quinoxaline was investigated and compared with their optical, electrochemical, hole mobility, and photovoltaic properties. Polymer solar cell (PSC) devices of the copolymers were fabricated with a configuration of ITO/ PEDOT: PSS/copolymers: PCBM (1:4 wt ratio)/Ca/Al. The best performance of the PSC device was obtained by using PbttpmobQ as the active layer. A power conversion efficiency of 1.42% with an open-circuit voltage of 0.8 V, a short-circuit current (JSC) of 5.73 mA cm(-2), and a fill factor of 30.9% was achieved under the illumination of AM 1.5, 100 mW cm(-2). 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 662-670, 2011