All Inorganic CsPbBr3 Perovskite Solar Cells Based on Preferential Crystallization of Buried Interface Regulated by CsCl

Compared to organic–inorganic hybrid perovskite solar cells (PSCs), all inorganic CsPbBr 3 perovskite solar cells have higher stability but lower efficiency. Owing to the low solid solubility of CsBr in methyl alcohol, an incomplete first-step reaction with PbBr 2 reaction takes place at room temperature. As a result, a large amount of CsPb 2 Br 5 is generated in the final CsPbBr 3 film, which deteriorates the performance of CsPbBr 3 PSCs. Along these lines, in this work, CsCl was added to increase the reaction between CsBr and PbBr 2 in the first step and high-quality CsPbBr 3 films were prepared without CsPb 2 Br 5 . Our analysis demonstrated that at the optimal CsCl concentration of 6% in CsBr solution, the CsPbBr 3 perovskite solar cells exhibited a power conversion efficiency of 7.33%. The best device retained 98.57% of the power conversion efficiency (PCE) after storing it for 30 days under ambient air condition.