Enhancing organic solar cell lifetime through humidity control using BCF in PM6 : Y6 active layers†

Enhancing the longevity of efficient organic solar cells (OSCs) remains a central focus in contemporary research. Many strategies have been explored, including material modifications in active layers, electrodes, interlayers, and encapsulation, all aiming at improving OSC lifetimes. This study introduces an innovative approach by incorporating a third element, the tris(pentafluorophenyl)borane (BCF) molecule, which interacts significantly with the active layer materials in OSCs. Functioning as a p-type dopant, BCF was carefully integrated into the active layer, resulting in power conversion efficiencies comparable to those of undoped devices. This allowed a detailed analysis of its influence on stability. Through systematic investigations, BCF's ability to react with water molecules, which acts in OSC degradation, was identified. Devices with BCF exhibited impressive enhancements in longevity, particularly evident in electrical properties, such as increased open-circuit voltage and hole mobility. Notably, the donor polymer experienced more pronounced alterations during degradation in the presence of BCF than the acceptor molecule. Quantum chemical calculations elucidated the regions of the polymer backbone interacting with BCF and the effects of this interaction. It is inferred that BCF's reaction with water generates protons, which subsequently associate with PBDB-T-2F (PM6) through the sulfur atom. In conclusion, this research demonstrates that BCF addition offers intrinsic protection to OSCs, leading to significant advancements in their durability.