Trifluorophenyl Side Chain Engineering in Benzotriazole‐Core Acceptors for High‐Performance Organic Photovoltaics

In this study, we explore an innovative approach to enhancing the photovoltaic performance of organic solar cells through core fluorination of the non‐fullerene acceptor. We developed a benzotriazole‐based non‐fullerene acceptor with a trifluorinated phenyl side chain, referred to as YNPF3, which has a significant impact on the molecular properties, including a surprisingly varied local dipole moment and crystalline nature, as well as effectively stabilizing the frontier molecular orbital energy levels. Furthermore, a trifluoro‐phenyl‐based non‐fullerene acceptor exhibits enhanced absorptivity, restricted voltage loss, and favorable photoactive morphology compared with its methyl side chain counterpart non‐fullerene acceptor. Consequently, a binary organic solar cell based on YNPF3 achieves an outstanding power conversion efficiency of 19.2%, surpassing the control device with a efficiency of 16.5%. Finally, the YNPF3‐based organic solar cell presents an impressive power conversion efficiency of 16.6% in a mini‐module device with an aperture size of 12.5 cm 2 , marking the highest reported efficiency for series‐connected binary organic solar cells with a photoactive area over 10 cm 2 .