Synthesis and Characterization of New TPD-based Copolymers and Applications in Bulk Heterojunction Solar Cells

Abstract

We developed and synthesized two novel polymeric semiconductor materials containing thienopyrrolodione (TPD) units, with one of the polymers also containing thiophene (T) units and the other containing bi-thiophene (BT) units, and denoted as TPD-T and TPD-BT, respectively. TPD-T and TPD-BT were studied for bulk heterojunction organic solar cells as blends with [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). The TPD-T-based device exhibited considerably better photovoltaic performances, with a power conversion efficiency of 2.51%, in contrast to the 1.63% value for the TPD-BT-based device. According to atomic force microscope images of the TPD-BT:PC71BM and TPD-T:PC71BM blend films, the latter showed more nanoscale phase aggregation, explaining its better photovoltaic properties.