Two new alternating copolymers based on dithienyl benzotriazole segment and phenylene vinyl unit were synthesized by Heck cross coupling method. The polymers exhibited broad absorption bands (from 300 nm to 752 nm for P1, and from 300 nm to 654 nm for P2) in the UV-visible region with optical bandgap ranging between 1.6 and 1.9 eV and proper electronic energy levels measured by cyclic voltammetry. The photovoltaic properties of the polymers as electron donors with 6.6-phenyl C61-butyric acid methyl ester as the electron acceptor in a bulk heterojunction structures were reported. Preliminary results showed moderate power conversion efficiency of 0.36% and 0.4%, respectively, under the illumination of AM 1.5, 100 mW/cm 2 with a device structure of ITO/PEDOT : PSS/polymer : PC(60)BM (1 : 3)/Ca/Al. Furthermore, the side chain effect on properties has also been investigated. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 2534-2542, 2011