Water-soluble CsPbBr3@SiO2 nanocomposite: Enhancing stability in aqueous environments

Abstract

CsPbBr3 all-inorganic lead halide perovskite nanocrystals have significant applications due to their unique photoluminescence properties. However, their poor stability and easy decomposition in water significantly limit their practical applications. Encapsulating cesium lead halide perovskite quantum dots (PQDs) within a stable shell has been proven to be an effective strategy for enhancing their stability. However, traditional methods of coating PQDs via direct hydrolysis of silicon source often result in particle aggregation or alterations in the original morphology and optical properties of the PQDs. In this study, we employed maleic anhydride to trigger the transformation of Cs4PbBr6 into CsPbBr3 nanocrystals (NCs). Simultaneously, maleic anhydride reacts with surface oleylamine (OAm) ligands to form maleic acid, which replaces the conventional oleic acid (OA) and oleylamine as ligands and surfactants. A uniform CsPbBr3@SiO2 nanocomposite was obtained, with a core size of approximately 9 nm and a shell thickness of about 15 nm. The absorption peak was located at 520 nm, with a full width at half maximum (FWHM) of around 25 nm. After one hour of dispersion in water, the water-soluble CsPbBr3@SiO2 nanocomposite maintained a high level of luminescence, with a photoluminescence (PL) loss of only 30.1 %. This approach enhances the affinity between PQDs and SiO2, improving the encapsulation efficiency of individual nanocrystals. This method not only prevents excessive hydrolysis and particle aggregation but also significantly enhances the water stability of CsPbBr3.