End-capped modification and computational evaluation of non-fused ring electron acceptors with high photovoltaic performance for organic solar cells

Non-fused ring electron acceptors (NFREAs) are a promising category of non-fullerene acceptors for organic solar cells due to their simpler synthesis and lower production costs. However, they often face challenges like low molecular planarity, high charge recombination, and inefficient charge transfer. In this study, eight new NFREAs (CP1-CP8) were designed through end-capped modifications based on a reference molecule using density functional theory to evaluate their photovoltaic properties. Among them, CP2 exhibited the lowest HOMO-LUMO gap (1.693 eV), excitation energy (1.338 eV), and binding energy (0.274 eV), compared to the reference molecule. CP7 demonstrated a balanced performance across all parameters, while CP4 achieved the highest open-circuit voltage of 1.767 eV and the highest power conversion efficiency of 33.31 %. Other analyses confirmed improvements in photoelectronic properties due to the end-capped modifications. Therefore, these newly designed molecules, with enhanced stability and photovoltaic performance, exhibit significant potential for organic solar cells.