Preparation of Ultrastable and Highly Luminescent CsPbBr₃ Quantum Dots by a Synergistic Internal and External Strategy of Ligand Modification and Silica Coating

Inorganic metal halide CsPbX3 (X = Cl, Br, and I) perovskite quantum dots (QDs) are widely used in light-emitting diodes, photodetectors, and solar cells due to their excellent optoelectronic properties. Their disadvantage is poor environmental stability, which can be improved to some extent by dynamic bonding of conventional organic acid/amine ligands to the surface of QDs. Here, we adopt an internal and external synergistic strategy by first introducing 4-sulfamoylbenzoic acid (4-SABA) during the synthesis process, which effectively modifies the uncoordinated Pb2+ and Br- vacancies on the surface of QDs. Second, a layered SiO(2 )substrate was generated by (3-aminopropyl) triethoxysilane hydrolysis to encapsulate the QDs, which finally achieved the dual protection effect of surface passivation and inorganic coating of the QDs. Results showed that the as-prepared 4-SABA-CsPbBr3/SiO2 composites had a higher photoluminescence quantum yield (96%) and far more stability to water and ethanol than the oleic acid-/oleylamine-passivated QDs. This paper provides an effective way to prepare QD solutions with not only low cost but also high efficiency.