Recent Advances in Functionalized Fullerenes in Perovskite Solar Cells†

Comprehensive Summary Efficient charge transport and defect passivation are essential for high efficiency of organic–inorganic hybrid perovskite solar cells (PSCs). Functionalized fullerenes featuring high electron affinity and mobility as well as small reorganization energy have been extensively applied in PSCs toward facilitated electron transport and passivated trap states, leading to improvements of both device efficiency and stability. Herein, we summarize the recent advances, especially in the last three years, in applications of functionalized fullerenes including fullerene derivatives and endohedral metallofullerenes in PSCs. Their functions in trap state passivation, electron transport promotion, crystalline modulation, water/oxygen erosion inhibition, and so on, are discussed in details. In particular, we emphasize novel functions of fullerenes beyond trap state passivation, as well as the synergy of multifunction of fullerenes in improving PSC device performance and stability. Finally, we present an outlook on designing novel multifunctionalized fullerenes toward highly efficient and stable PSC devices.