Partial substitution with furan units for modulating charge transport ability of regio-random polythiophene

Abstract

Random copolymerization is a promising strategy for finely modulating crystal, morphological, and electrical properties of semiconducting conjugated polymers for electronic device applications. Herein, a new series of regio-random thiophene polymers were synthesized by partially substituting non-alkylated furan units into the conjugated backbone to enhance the inter- and intramolecular interactions. The systematic tuning of the monomer ratio revealed the dramatic effects of furan substitution on the charge transport ability of the polymers. The optimized-polymer field-effect transistors showed enhanced mobility of over 4 cm2V−1s−1 compared to the control polymer with no furan substitution (≈2 cm2V−1s−1), using electrolyte gating, which substantially exceeds devices with conventional polymer dielectric (10−2 cm2V−1s−1), attributing to improved charge carrier density in the semiconducting channel and film crystallinity. Also, using the synthesized polymers as hole transport materials for silver bismuth sulfide (AgBiS2) nanocrystal solar cells showed high power conversion efficiencies of 5.75 % and 4.09 % for the optimized and control polymers, respectively. This study will provide new insight into improving the crystallinity of random polymers for high-performance solution-processable electronic devices.