Ambipolar copolymer of dithienocoronenedi-imide and benzo(bis)thiadiazole with balanced hole and electron mobility

Abstract

A new copolymer P(DTCBTZ) of dithienocoronenediimide (DTCDI) and benzo(bis)thiadiazole (BTZ) as the active layer of organic field-effect transistors (OFETs) is reported. The combination of DTCDI with long alkyl chains and BTZ without alkyl chains results in reduced steric hindrance between acceptors of different polymer backbones. 2,2′-bithiophene is introduced into P(DTCBTZ), and thus donor–acceptor (D–A) interactions are induced. Absorption spectra of solution and thin films of P(DTCBTZ) reveal the existence of relatively strong aggregations of P(DTCBTZ) copolymers in solid state. The new copolymer of P(DTCBTZ) has a HOMO of −5.54eV and a LUMO of −3.72eV, which are suitable for both hole and electron transport. Bottom-gate and top-contact (BGTC) transistors were prepared and balanced charge transport was observed, with hole mobility of 0.018cm2V−1s−1 and electron mobility of 0.019cm2V−1s−1, indicating potential for application of polymers containing DTCDI in ambipolar semiconductors.