Synergistic bonding stabilized interface for perovskite solar cells with over 24% efficiency

Planar-type perovskite solar cells have attracted extensive attentions due to their simple architecture and manufacturing. However, an imperfect heterojunction at the electron-selective contact side with abundant detrimental defects and weak binding strength induces severe charge recombination and device instability during long-term operation, which seriously hinders the further development and application prospect. Herein, we demonstrate π-conjugated oxysalt as an efficient interfacial binder and defect passivator for the stabilization of SnO2/perovskite interface. Theoretical modeling and experimental studies confirm the synergistic effect of ionic bonding and π-cation interaction in reducing defect density and mitigating charge recombination. An impressive power conversion efficiency up to 24.05%, a fill factor as high as 84.52%, and negligible hysteresis can be achieved in optimized solar cell. π-conjugated oxysalt interlayer can also improve device stability by offering a robust interface. Our work highlights the significance of chemical bonding engineering in constructing a high-quality heterojunction for efficient and stable perovskite solar cells.