A Versatile Bridging Molecule Managed the Buried SnO/Perovskite Interface for Efficient and Stable Perovskite Solar Cells.

Buried interface in perovskite solar cells (PSCs) is a critical determination for the performance and stability because it dominates the crystallization of the perovskite layer, non-radiative recombination, and ion migration at the interfaces. Herein, a novel versatile modifier, potassium sucrose octasulfate (KSOS) which is rich in sulfonic groups and potassium ions, is introduced for bridging the buried perovskite and SnO interface, to improve the interfacial states and further the device performance. It is found that KSOS serves as a bridge that can not only passivate defects in perovskite and SnO through multi-site strengthening chemical binding, thus effectively inhibiting non-radiation recombination and suppressing ion migration, but also can optimize the surface state of SnO layer, improve the crystallization of perovskite absorber, thus ultimately achieving a gratifying efficiency of 25.32% with negligible hysteresis. What's more, the optimized device delivers admirable stability sustaining over 90% of initial power conversion efficiency after being aged under continuous 85 °C heating stress with 40 ± 5% RH humidity for ≈600 and ≈1200 h under continuous 1-sun illumination, respectively.