Enhanced Performance of CsPbBr3 Nanocrystals via Dual Passivation

Abstract Perovskite CsPbBr 3 nanocrystals show excellent optical properties. However, the nanocrystals encounter a major challenge of poor stability. In this study, an effective approach is proposed for enhancing the stability of CsPbBr 3 nanocrystals via a dual passivation strategy, where the dual passivation layer is composed of alumina (Al 2 O 3 ) and polymer ethylene‐vinyl acetate (EVA). The Al 2 O 3 coating on the CsPbBr 3 surface is realized by in situ oxidation of trimethyl aluminum (TMA), which passivated the surface defects while blocking the intrusion of water and oxygen. The EVA film is formed by a solution method, which can further block the water and oxygen, and form the flexible composite with perovskite CsPbBr 3 nanocrystals with enhanced stability toward water and heat. After soaking for 360 h and heating for 5 h, the photoluminescence (PL) intensity is higher than that without passivation. The polymer EVA packaging strategy provided CsPbBr 3 with excellent extensibility and flexibility at 100% and 200% tensile rates, the PL intensity remains 91% and 88% of the initial intensity, which returns to the initial value after stretching. The unique dual‐protection structure significantly improves the water and thermal stability of the nanocrystals. The strategy might point out the direction for the future application of perovskites.