Bithienopyrroledione‐Based Copolymers, Versatile Semiconductors for Balanced Ambipolar Thin‐Film Transistors and Organic Solar Cells with Voc > 1 V

Conjugated polymer semiconductors P1 and P2 with bithienopyrroledione (bi‐TPD) as acceptor unit are synthesized. Their transistor and photovoltaic performances are investigated. Both polymers display high and balanced ambipolar transport behaviors in thin‐film transistors. P1‐based devices show an electron mobility of 1.02 cm2 V−1 s−1 and a hole mobility of 0.33 cm2 V−1 s−1, one of the highest performance reported for ambipolar polymer transistors. The electron and hole mobilities of P2 transistors are 0.36 and 0.16 cm2 V−1 s−1, respectively. The solar cells with PC71BM as the electron acceptor and P1/P2 as the donor exhibit a high Voc about 1.0 V, and a power conversion efficiency of 6.46% is observed for P1‐based devices without any additives and/or post treatment. The high performance of P1 and P2 is attributed to their crystalline films and short π–π stacking distance (<3.5 Å). These results demonstrate (1) bi‐TPD is an excellent versatile electron‐deficient unit for polymer semiconductors and (2) bi‐TPD‐based polymer semiconductors have potential applications in organic transistors and organic solar cells.