Non-fullerene acceptors in organic solar cells

Abstract

Organic solar cells (OSCs) have become a promising option for the next generation of solar energy technology because they are flexible, lightweight, and can be made in large quantities at a lower cost. In recent years, there has been a major change in the field, moving away from using fullerene-based materials as the main component. Instead, non-fullerene-based acceptors (NFAs) are now being used. These NFAs have several benefits, including the ability to adjust energy levels, absorb a wider range of light, more stable, and reduce voltage loss compared to fullerene-based materials. Collectively, this enabled OSCs to achieve power conversion efficiencies (PCEs) exceeding 19 percent, marking significant progress toward commercialization. Several factors, like how molecules are designed, side-chain engineering, modifications to end groups, and the use of fused-ring electron acceptor (FREA) cores, have played a key role in improving phase separation, charge transport, and device stability. This review highlights the design, evolution, principles, and recent breakthroughs in NFAs development, emphasizing their critical role in advancing the performance and stability of OSCs.