A series of donor-acceptor (D-A) alternating copolymers (P1, P2 and P3) with thiophene -benzothiadiazole-thiophene-triphenylamine main chain have been synthesized by Suzuki poly-condensation. P1, P2, and P3 possess medium optical band gaps of 1.99, 1.97 and 1.93 eV, respectively. Bulk heterojunction polymer solar cells (BHJ PSCs) with these polymers as donor and PC71BM as acceptor showed power conversion efficiency (PCE) in the range of 2.1-2.8%. The highest PCE of 2.8 % was achieved for P1 with short circuit current (J(SC),) of 7.8 mA/cm(2). This study offers a useful and important insight for designing triphenylamine derivative-based polymers used for efficient PSCs. (C) 2011 Elsevier Ltd. All rights reserved.