Thiophene-thiazole based Semiconducting Copolymers for High Performance Polymer Field-effect Transistors

Abstract: We report a newly-synthesized donor (D)-acceptor (A) type semiconducting copolymer consisting of thiophene as electron donating and thiazole as electron accepting unit for active layer of organic field-effect transistors (OFETs). In particular, this study was to investigate the structure and electrical property relationships of the thiophene-thiazole based semiconducting copolymers with comprehensive analyses on the charge-transporting properties corresponding to the structural changes upon the spin-speed of spin-coater during the formation of the semiconducting copolymer film. The crystallinity of the semiconducting copolymer films were examined with grazing incidence X-ray diffraction (GIXRD). Temperature-dependent transfer measurements of the OFETs were conducted to extract the density of states (DOS) and characterize the charge-transport property. The comparative analyses of the charge-transports within the framework of physical model based on polaron hopping and Gaussian DOS revealed that the pre-factors of both physical charge transport models are depend on the spin coating condition for the semiconducting polymer films while the polaron hopping energy or the width of distribution of the localized site are more and less independent. Based on the analyses, it is suspected that the semiconducting copolymer film with the faster spin-rates during the spin-coating may have more efficient electronic coupling between the neighboring molecules.