Chlorofullerene C_(60)Cl_(6) Enables Efficient and Stable Tin-Based Perovskite Solar Cells

Tin-based perovskite solar cells(TPSCs)have received great attention due to their eco-friendly properties and high theoretical efficiencies.However,the fast crystallization feature of tin-based perovskites leads to poor film quality and limits the corresponding device performance.Herein,a chlorofullerene,C_(60)Cl_(6),with six chlorine attached to the C_(60)cage,is applied to modulate the crystallization process and passivate grain boundary defects of the perovskite film.The chemical interactions between C_(60)Cl_(6)and perovskite components retard the transforming process of precursors to perovskite crystals and obtain a high-quality tin-based perovskite film.It is also revealed that the C_(60)Cl_(6)located at the surfaces and grain boundaries can not only passivate the defects but also offer a role in suturing grain boundaries to suppress the detrimental effects of water and oxygen on perovskite films,especially the oxidation of Sn^(2+)to Sn^(4+).As a result,the C_(60)Cl_(6)-based device yields a remarkably improved device efficiency from 10.03%to 13.30%with enhanced stability.This work provides a new strategy to regulate the film quality and stability of TPSCs using functional fullerene materials.