Non‐Radiative Recombination Energy Losses in Non‐Fullerene Organic Solar Cells

Abstract Impressive short‐circuit current density and fill factor have been achieved simultaneously in single‐junction organic solar cells (OSCs) with the emergence of high‐performance non‐fullerene acceptors. However, the power conversion efficiencies (PCEs) of OSCs still lag behind those of inorganic and perovskite solar cells, mainly due to the modest open‐circuit voltage ( V OC ) imposed by relatively large energy loss ( E loss ). Generally, E loss in solar cells can be divided into three parts. Among them, Δ E 1 is inevitable for all photovoltaic cells and depends on the optical bandgap of solar cells, while radiative recombination energy loss, Δ E 2 , in OSCs can approach the negligible value via finely matching donor with acceptor material in the blend. The relatively large non‐radiative recombination energy loss, Δ E 3 , becomes the main barrier to further reduce E loss and thus enhance PCE in non‐fullerene acceptor‐based OSCs. In this review, the recent studies and achievements about Δ E 3 in non‐fullerene acceptor‐based OSCs have been summarized from the aspects of material design, morphology manipulation, ternary strategy, mechanism, and theoretical study. It is hoped that this review helps to get a deep understanding and boost the advance of Δ E 3 study in OSCs.