Design and synthesis of indole-substituted fullerene derivatives with different side groups for organic photovoltaic devices

► A series of indole-substituted fulleropyrrolidine derivatives were synthesized. ► The derivatives were used as acceptors in the active layer of organic solar cells. ► The structure-property relationship of the fullerene derivatives was investigated. ► The results of photovoltaic devices were consistent with those of XRD experiments.