LAUSR

Abstract A novel medium band gap copolymer ( PBO ) based on benzodithiophene (BDT) and benzoxadiazole (BOz) was synthesized and applied in polymer solar cells (PSCs). The introduction of two alkylthio side chains onto the BDT unit can endow the resulting polymer ( PBO ) with good solubility in solutions and good crystallinity in the solid state. The low HOMO level of −5.52 eV and the broad absorption ranging from 350 to 700 nm make PBO a promising donor material for PSCs. Power conversion efficiency higher than 7% has been achieved for devices using PBO as the donor material and PC 71 BM or ITIC as the acceptor material.