LAUSR

Abstract The wide range of the perylenediimide electron acceptors developed for non-fullerene organic solar cells (NF–OSCs) is an essential step to enhance the power conversion efficiency (PCE) of the resulting devices. Here, a novel quasi-two-dimensional electron acceptor (SF-FPDI) based on perylenediimide fused dimer (FPDI) moiety was synthesized, which exhibits a strong absorption in the 300–580 nm region with a wide optical band gap of 2.04 eV, and a suitable lowest unoccupied molecular orbital (LUMO) level of −3.92 eV. By blending SF-FPDI with a classical polymer donor (PTB7-Th), the additive-free devices achieved a high efficiency of 6.24% with a low energy loss of 0.72 eV, respectively is the smallest reported for FPDI-based fullerene-free acceptors up to date.