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

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.