One-step sintering strategy synergistically enhances luminescence and stability of silica-coated CsPbBr₃ quantum dot powders

All-inorganic CsPbX 3 perovskite quantum dots exhibit exceptional optoelectronic properties but are limited by intrinsic instability. While silica coating methods can provide an effective stabilization solution, conventional processes typically form porous and poorly protective silica shells and often cause quantum dot degradation during coating. This study innovatively proposes a post-treatment strategy by introducing an additional sintering step after the formation of the porous silica layer, leading to further densification of the silica shell and producing sintered silica-coated CsPbBr 3 powders (S-SQDs) with synergistically enhanced luminescence and stability. Through systematic characterization, this study clearly demonstrates that sintering at 448 K induces structural reconstruction via dehydration condensation on the CsPbBr 3 surface, transforming the loose silica matrix into a dense protective layer while eliminating phase impurities, ultimately yielding a silica coating with passivated surface defects and optimized luminescent properties. The optimized S-SQDs exhibit a photoluminescence quantum yield (PLQY) of 75.97 %, a narrow emission linewidth (FWHM) of 19.23 nm, a 2.4-fold lifetime extension, and exceptional stability-maintaining over 82 % of their initial luminescence after 150 min in water. Flexible S-SQDs@PMMA films retain over 80 % luminescence under more severe humidity/UV conditions while meeting the Rec. 2020 color standard, demonstrating broad application prospects in high-stability displays and solid-state lighting.