Achieving 17.4% Efficiency of Ternary Organic Photovoltaics with Two Well‐Compatible Nonfullerene Acceptors for Minimizing Energy Loss

Abstract A power conversion efficiency (PCE) of 16.2% is achieved in PM6:BTP‐4F‐12 based organic photovoltaics (OPVs). On the basis of efficient binary OPVs, a series of ternary OPVs are constructed by incorporating MeIC as the third component. The open circuit voltages ( V OC s) of ternary OPVs can be gradually increased along with the incorporation of MeIC, suggesting the formation of an alloy state between BTP‐4F‐12 and MeIC with good compatibility. The energy loss ( E loss ) of ternary OPVs can be decreased compared with that of two binary OPVs, contributing to the V OC improvement of ternary OPVs. The short circuit current density ( J SC ) and fill factor (FF) of ternary OPVs can also be simultaneously enhanced with MeIC content up to 10 wt% in acceptors, leading to 17.4% PCE of the optimized ternary OPVs. The J SC and FF improvement of ternary OPVs is thought to result from the optimized ternary active layers with more efficient photon harvesting, exciton dissociation and charge transport. The 17.4% PCE and 79.2% FF is among the top values of ternary OPVs. This work indicates that a ternary strategy is an emerging method to simultaneously minimize E loss and optimize photon harvesting as well as improve the morphology of active layers for realizing performance improvement for OPVs.