A novel complementary absorbing donor-acceptor pair in block copolymers based on single material organic photovoltaics

We report on the first synthesis of a highly crystalline donor-acceptor low band gap block copolymer by using diketopyrrolopyrrole (DPP) as a low band gap block and perylenebisimide (PDI) as a strong acceptor block. All important prerequisites for PV applications such as strong and broad optical absorption, compatible HOMO-LUMO levels can be accomplished and combined on one macromolecule at the same time. Besides, microphase separation is achieved by solvent annealing the film in dichloromethane and the PV performance is improved from 0.25% to 0.89%. The morphology and performance of this single component system can be enhanced by further improvements under processing conditions.