New dithienophosphole-based donor–acceptor alternating copolymers: Synthesis and structure property relationships in OFET

Abstract

Two donor acceptor conjugated copolymers comprised of a novel dithienophosphole (DTP) as the acceptor unit and bithiophene (BT) or decylthiophenebenzodithiophene (DTBDT) as the donor unit were synthesized and characterized to elucidate the relationship between donor acceptor (D-A) architecture and organic field-effect transistors (OFETs) performance. These characteristics of D-A copolymers were affected by the structural suitability of donor and acceptor units. Poly(DTP-BT) had an ordered structure that facilitated charge carrier transfer. The crystallinity of poly(DTP-BT) increased as annealing temperature (T-ann) increased. In contrast, poly(DTP-DTBDT) was amorphous regardless of Tann due to the long alkyl chains of the DTBDT units. OFET devices made with poly(DTP-BT) and annealed at 200 degrees C exhibit a highly crystalline morphology and a relatively high field-effect mobility (4.9 x 10(-3) cm(2)/(V.s)).