Triphenylamine-based polymers with fluorinated electron-acceptor groups as hole-transport materials for perovskite solar cells

Organic semiconducting polymers based on triphenylamine of donor-acceptor structure are promising hole-transport layer (HTL) materials in perovskite solar cells (PSCs) with n-i-p configuration. In this work, we report four new triphenylamine-based homopolymers of donor-acceptor structure containing different fluorinated electron acceptor groups. The homopolymers are readily synthesized by oxidative polymerization of the corresponding monomers using of FeCl₃ as an oxidant. They combine hole mobility, thermal and electrochemical stability and can be synthesized in a simple and easily scalable manner. By using the new polymers blended with the reference poly(triarylamine) PTA as HTL in n-i-p PSCs, the power conversion efficiency was improved from 18.4 % up to 19.9 %. The consistent increase in the open circuit voltage and fill factor values suggests that these polymer blends enable more efficient extraction and/or transport of charge carriers as compared to the single-component polymer films.