Novel two-dimensional donor-acceptor conjugated polymers containing quinoxaline units: Synthesis, characterization, and photovoltaic properties

Novel two-dimensional donor-acceptor (D-A) structured conjugated polymers, P1-P4, were designed and synthesized by introducing electron-deficient quinoxaline as core and electron-rich alkoxyl-phenylenevinylene in side chains and p-phenylenevinylexle, triphenylamine, or thiophene in main chain. Benefited from the D-A structures, the polymers possess low bandgaps of 1.75 eV, 1.86 eV, 1.59 eV, and 1.58 eV for P1, P2, P3, and P4, respectively, and show broad absorption band in the visible region: the shorter wavelength absorption peak at similar to 400 nm ascribed to the conjugated side chains and the longer wavelength absorption peak between 500 run and 750 nm belonging to the absorption of the conjugated main chains. Especially, the absorption band of P4 film covers the whole visible range from 300 mn to 784 mn. The power conversion efficiencies of the polymer solar cells based on P1-P4 as donor and PCBM as acceptor are 0.029%, 0.14%, 0.46%, and 0.57%, respectively, under the illumination of AM 1.5, 100 mW/cm(2). The polymers with the low bandgap and broad absorption band are promising photovoltaic materials. (c) 2008 Wiley Periodicals, Inc.