A new 3,6-dithien-2-yl-2,5-dialkylpyrrolo[3,4-c]pyrrole-1,4-dione (DTDPP) based polymer, poly {thieno[3,2-b]thiophene-alt-3,6-dithien-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione} (PTT-DTDPP) was synthesized by the Stilln coupling reaction. The polymer shows a broad absorption in visible and near infrared region and displays suitable HOMO/LUMO energy levels for marching with those of PCBM acceptor. The photovoltaic properties of the polymer were studied by bulk heterojunction solar cell devices using PTT-DTDPP as donor and PC(71)BM as acceptor. The power conversion efficiency of device achieved 1.60% under the illumination of AM1.5 G, 100 mW/cm(2). (C) 2011 Elsevier B.V. All rights reserved.