In situ lead oxysalt passivation layer for stable and efficient perovskite solar cells.

A Rb 2 SO 4 additive is employed to passivate the Pb 2+ defects in a perovskite film by forming PbSO 4 in situ , which can cover the surface and grain boundaries of the perovskite to ensure that the film is not decomposed by moisture. Finally, a device based on the Rb 2 SO 4 modification achieved an enhanced power conversion efficiency (22.25%) and long-term stability.