Impact of an electron withdrawing group on the thiophene-fused benzotriazole unit on the photovoltaic performance of the derived polymer solar cells

In this work, two new donor-acceptor (D-A) copolymers (P32 and P33) for non-fullerene polymer solar cells (PSCs) have been synthesized based on a thiophene-fused benzotriazole (BTAZT) unit and thiophene substituted benzodithiophene (BDTT) unit, in which two different electron-withdrawing groups (i.e., fluorine and ester groups) have been introduced at the side of BTAZT unit, respectively. It is found that P32 with a long alkyl chain ester group...