Random copolymers with different Cl position for optimizing morphology with acceptor

Abstract

We prepared a series of D-A-D' type random copolymers, which are based on PBDB-S-3Cl and PBDB-S-4Cl, PBDB-S-CO-3Cl-4Cl (1:9), PBDB-S-CO-3Cl-4Cl (3:7), PBDB-S-CO-3Cl-4Cl (7:3) and PBDB-S-CO-3Cl-4Cl (9:1) with 3-chloro or 4-chloro and 2-s-alkylated thiophene on benzodithiophene (BDT), to examine the position effects of chlorine substitution of PBDB-S on its photovoltaic performance in organic photovoltaics (OPVs). The modulation of composition of random copolymer with the position effects of chlorine substitution affect the performance of organic photovoltaic (OPV) devices. The PBDB-S-CO-3Cl-4Cl (9:1) random copolymer-based OPV devices exhibit the highest power conversion efficiency (PCE) of 13.31%, and fill factor (FF) of 0.63, which was higher performance than those of homopolymer PBDB-S-3Cl and PBDB-S-4Cl.