Organic Tetrabutylammonium Cation Intercalation to Heal Inorganic CsPbI₃ 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 CsPbI₃ to effectively substitute the Cs cation and to form one-dimensional (1D) TBAPbI₃ layer in the post-synthesis TBAI treatment. Such TBA cation intercalation leads to in situ formation of TBAPbI₃ protective layer to heal defects at the surface of inorganic CsPbI₃ perovskite. The TBAPbI₃ -CsPbI₃ 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 15.85 % of the control one.