LAUSR

For perylenediimide derivatives it seems that twisted structures are essential to avoid excessive aggregation tendencies and realize high-performance fullerene-free solar cells. However, in this communication, we designed and synthesized two planar inside-fused perylenediimide dimers, TDI2 and BDT-TDI2. Theoretical calculations reveal that both TDI2 and BDT-TDI2 have a highly planar molecular conformation with small dihedral angles of 0.02° and 11.4° between two TDI segments, respectively. By using BDDT as the donor polymer, power conversion efficiencies (PCEs) of the photovoltaic cells reached 5.80% for TDI2 and 4.52% for BDT-TDI2, with high open-circuit voltages (VOC) of ∼1.0 V. These results indicate planar PDI-dimer derivatives are also possible electron acceptors to realize high-performance fullerene-free solar cells.