Synthesis of low bandgap polymer based on 3,6-dithien-2-yl-2,5-dialkylpyrrolo[3,4-c]pyrrole-1,4-dione for photovoltaic applications

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 Stille 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 PC71BM as acceptor. The power conversion efficiency of device achieved 1.60% under the illumination of AM1.5 G, 100 mW/cm2.