High-performance Fullerene Derivatives with a Fulleropyrrolidine Unit

　Fullerene is a well-known major n-type organic semiconductor used in organic electronics devices. Solution-processable n-type organic semiconductors have been developed by functionalization of fullerene. Aso et al. developed fullerene derivatives with fulleropyrrolidine units (1, 2), and reported a photovoltaic performance comparable to that for the conventional methanofullerene derivative, PCBM.¹⁾ It is expected that the manufacturing cost of fulleropyrrolidine derivatives will be low because of the short synthesis process.
　Organic photovoltaics (OPVs) offer advantages such as light weight, mechanical flexibility, solution processability, and large-area manufacturing capability. Additionally, OPVs have a high absorption coefficient and a tunable absorption range, making them suitable for indoor applications, similar to robust inorganic silicon solar cells. Recently, Yasuda et al. reported a high power conversion efficiency for OPVs containing a bulk heterojunction using 1 and small molecular donors or macromolecular donors under indoor light.^2,3)