Solution-processable small molecules based on thieno[3,4-c]pyrrole-4,6-dione for high-performance solar cells

New series of thieno[3,4-c]pyrrole-4,6-dione(TPD)-based small molecules with donor–acceptor–donor structure were synthesized by palladium(0)-catalyzed Stille coupling reaction. The thermal, electrochemical, optical, charge transport, and photovoltaic properties of these small molecules were examined. These molecules exhibit strong absorption at 460–490 nm and low HOMO levels (−5.26 to −5.34 eV). Field-effect hole mobilities of these molecules are 0.8–1.3×10−3 cm2 V−1 s−1. Solution processed bulk heterojunction organic solar cells based on the blends of these molecule donors and PC71BM acceptor exhibit power conversion efficiencies as high as 3.31% under AM1.5, 100 mW cm−2.