Recent development of perylene diimide-based small molecular non-fullerene acceptors in organic solar cells

Recently, perylene diimide (PDI) derivatives were attractive as the electron-deficient acceptor materials in non-fullerene organic solar cells since Tang first used a single PDI compound as the n-type semiconductor to fabricate photovoltaic devices in 1986, which achieved a power conversion efficiency of 1%. Beside the monomeric PDIs, the linear and three dimensional (3D) PDI-based small molecular acceptors have also made great achievements with the power conversion efficiencies over 9.0% in single-junction polymer solar cells, and over 10.0% in tandem solar cells. The excellent device performance can be realized by forming suitable twisted structure, developing suitable donor materials and optimizing device technologies. In this review, we summarize the recent development of PDI-based small molecular non-fullerene acceptors in non-fullerene organic solar cells, including molecular design strategies and structure-property relationships.