Encapsulation of CsPbX3 Perovskite Nanocrystals via Hydrogen-Bonded Cocrystals Assisted by Pyr14BF4 Ionic Liquid to Enhance Their Stability

CsPbX 3 perovskite nanocrystals (NCs) have attracted considerable attention for their exceptional optoelectronic properties, yet their poor stability hinders practical applications. In this study, we developed a hydrogen-bonded cocrystal-coated composite (CsPbX 3 @CA-M) by exploiting the rapid co-crystallization of cyanuric acid (CA) and melamine (M) assisted by the ionic liquid Pyr 14 BF 4 (IL). The IL effectively coordinated with unbonded Pb atoms on the perovskite surface, suppressing surface defects and enhancing both quantum efficiency and stability. Simultaneously, the CA-M cocrystal layer further reduced trap states through covalent bonding, improving structural robustness. The CsPbBr 3 @CA-M composite retained its crystallinity and strong photoluminescence under UV irradiation and in 1 m NaOH or 1 m HNO 3 , demonstrating remarkable chemical durability. Even after 30 days of storage, its photoluminescence intensity remained nearly unchanged, whereas that of uncoated CsPbBr 3 NCs decayed rapidly. These findings confirm that CA-M cocrystal encapsulation effectively shields perovskite NCs from environmental degradation, offering a simple and efficient strategy to simultaneously enhance their stability and optoelectronic performance.