Monocyclopropanated fullerene derivatives with decreased electron affinity as promising electron acceptor materials for organic solar cells

Monocyclopropanated fullerene derivatives with decreased electron affinity as compared to standard [60]PCBM acceptor were synthesized, characterized, and investigated as promising electron acceptor materials for fullerene-based organic solar cells. This decrease in electron affinity was attributed to the presence of through space electronic interactions between the lone electron pairs of oxygen atoms and electron-deficient pi-system of the fullerene cage. Organic bulk heterojunction solar cells based on the designed materials blended with conjugated polymers P3HT and PCDTBT have demonstrated spectacular increase in open-circuit voltage by >100 mV and improved light power conversion efficiency as compared to the reference devices comprising [60]PCBM. The application of new fullerene-based acceptor materials in combination with the promising low band gap conjugated copolymer may deliver competitive device performances.