Chlorination converting one efficient polymeric donor to an effective electron acceptor in organic solar cells

Abstract Chlorination converts an efficient isoindigo (IID)‐based electron donor material to an effective electron acceptor material, which could pair with different donor materials. The polymer PAZ could work as the donor and achieve moderate power conversion efficiency of 3.56%, but organic solar cells based on the blend of PC71BM and the chlorinated analogue PAZ‐Cl fail. On the contrary, only PAZ‐Cl could be used as the acceptor material matching with typical donor polymers, such as PTB7‐Th, J52 and J52‐2Cl. Simulation based on density functional theory suggests that the main reason for this transform might be attributed to the change in the electrostatic potential of the polymers. This research paves a new way to design novel electron acceptors for organic solar cells.