Synthesis, characterization and photovoltaic performances of D-A copolymers based on BDT and DBPz: the largely improved performance caused by additional thiophene blocks

摘要

Two new low bandgap copolymers, PBDT-DBPz and PBDT-DTDBPz, were prepared, in which the only difference was the additional added thiophene bridge between the BDT donor unit and DBPz acceptor unit for PBDT-DTDBPz. In addition to the improvements of UV-vis absorption and hole mobility, the PSC based on PBDT-DTDBPz:PC_(71)BM demonstrated a power conversion efficiency of 4.75%, much higher than that of the device based on PBDT-DBPz:PC_(71)BM (0.46%), under the same experimental conditions.