Additive-induced intermolecular interaction enhancement enables highly efficient organic solar cells

Morphology optimization is a critical factor for achieving high power conversion efficiency (PCE) in organic solar cells (OSCs). Herein, a simple yet effective solvent additive-induced morphology control method employing 3-chloropyridine (PDC) is reported, which carries more electronegative nitrogen atoms, resulting in stronger intermolecular interaction with non-fullerene acceptors (NFAs). The enhanced intermolecular interaction can enhance the red-shifted absorption of the acceptor phase in the active layer, leading to improved crystallinity and ordered molecular stacking. Consequently, the PCE of PM6:Y6 OSCs treated with PDC increased significantly from 16.28% to 17.72% and has great universality in other Y-series NFAs, achieving notable improvements in PM6:eC9 and PM6:N3 systems. These findings highlight that achieving strong non-covalent interactions between the solvent additive and the non-fullerene acceptor is a promising approach to enhance OSC photovoltaic performance. © 2024 The Royal Society of Chemistry.