Supramolecular Cucurbit[5]uril Modulates the Buried SnO₂/Perovskite Interface for Efficient and Stable Perovskite Solar Cells

Abstract Reducing non‐radiative recombination caused by defects at buried interfaces is crucial to the development of efficient and stable perovskite solar cells (PSCs). Herein, supramolecular cucurbit[5]uril (CB[5]) is introduced into the SnO 2 layer, where it engages in host–guest interactions to suppress oxygen vacancies in SnO 2 , prevent particle aggregation, and enhance the electron mobility of SnO 2 . By serving as a bridging agent at the buried interface between SnO 2 and the perovskite layer, CB[5] reduces the defect density and improves the carrier extraction efficiency. It also enhanced the surface energy of the SnO 2 substrate, facilitates the formation of large grains in the perovskite film, alleviates residual lattice stresses, and enhances the film quality. Consequently, the PSC with CB[5] shows a champion power conversion efficiency of 24.83%. Moreover, an unencapsulated device incorporating CB[5] retains more than 87% of its initial PCE under continuous illumination at the maximum power point tracking for 1000 h. This study pioneers the utilization of cucurbiturils in PSCs and provides insights into how supramolecular compounds can regulate buried interfaces.