Bichalcogenophene Imide-Based Homopolymers: Chalcogen-AtomEffects on the Optoelectronic Property and Device Performance in OrganicThin-Film Transistors

Driven by the exceptional success of 2,2′-bithiophene-3,3′-dicarboximide imide (BTI) for enabling high-performance polymer semiconductors, herein two BTI analogues 2,2′-bifuran-3,3′-dicarboximide (BFI) and 2,2′-biselenophene-3,3′-dicarboximide (BSeI) are designed and synthesized. The strong electron-withdrawing imide group enables BFI and BSeI with high electron deficiency, differing from typical furan- and selenophene-based building blocks, which are electron-rich. Hence, n-type polymers can be derived based on these two new imides. To investigate the effects of chalcogen-atom substitution on the physicochemical properties and device performance of these imide-bridged materials, two homopolymers PBFI and PBSeI are synthesized together with the previously reported PBTI as control. Structures, optoelectronic properties, and charge transport characteristics of PBFI and PBSeI are studied and compared to those of the thiophene-based analogue PBTI in depth. The optical band gap (Egopt) of the dibrominated bich...