Emerging electronic applications of fullerene derivatives: an era beyond OPV
Hummelen et al. for the first time reported the synthetic route and characterization of a soluble methanofullerene derivative in 1995. In the same year, such a fullerene derivative was successfully used as the acceptor of internal donor-acceptor heterojunctions in the field of organic photovoltaics (OPV). Since then, it has opened an era of fullerene derivatives towards OPV application until 2015. Beyond OPV, several new research directions for solution-processable fullerene derivatives recently appeared, including perovskite solar cells, organic thermoelectrics, molecular electronics, and organic electrochemical transistors. This review highlights the important role of fullerene derivatives in these emerging research areas and summarizes the recent progress in the development of fullerene derivatives in these new research fields. These fields require fullerene derivatives with new properties, such as strong electron-donating ability, large polarity, or excellent water permeability. Therefore, new design strategies of fullerene derivatives and device engineering considerations are desired.