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

Abstract

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 cm², marking the highest reported efficiency for series-connected binary organic solar cells with a photoactive area over 10 cm².