Organic Tetrabutylammonium Cation Intercalation to Heal Inorganic CsPbI ₃ Perovskite

The in-situ formation of reduced dimensional perovskite layer via post-synthesis ion exchange has been an effective way of passivating organic-inorganic hybrid perovskites. In contrast, cesium ions in Cs based inorganic perovskite with strong ionic binding energy cannot exchange with those well-known organic cations to form reduced dimensional perovskite. Herein, we demonstrate that tetrabutylammonium (TBA + ) cation can intercalate into CsPbI 3 to effectively substitute the Cs cation to form one-dimensional (1D) TBAPbI 3 layer in the post-synthesis TBAI treatment. Such TBA cation intercalation leads to in-situ formation of TBAPbI 3 protective layer to heal defects at surface of inorganic CsPbI 3 perovskite. The TBAPbI 3 -CsPbI 3 perovskite exhibited enhanced stability and lower defect density, and the corresponding perovskite solar cell devices achieved an improved efficiency up to 18.32% compared to the control one's efficiency of 15.85%. Our findings would inspire further investigation and development of reduced dimensional perovskite protection strategy for inorganic perovskites.