Ultra‐stable perovskite quantum dot composites encapsulated with mesoporous SiO2 and PbBr(OH) for white light‐emitting diodes

Lead halide perovskite quantum dots (QDs) with high fluorescence efficiency and high color purity have a broad application prospect in the field of backlight display, but poor stability has been a key factor limiting their commercialization. Herein, we successfully synthesized CsPbBr3 QDs‐KIT‐6 (CsPbBr3‐K6) composite by using KIT‐6 molecular sieve as the limited template with a simple high temperature solid‐phase method. Further, the semi‐protected CsPbBr3 QDs in KIT‐6 frame will spontaneously hydrolyze when encountering water, and finally the double‐encapsulated CsPbBr3 QDs‐KIT‐6@PbBr(OH) (CsPbBr3‐K6@PbBr(OH)) composite are obtained. CsPbBr3‐K6@PbBr(OH) composite shows excellent green emission properties, including a photoluminescence quantum yield (PLQY) (~73%) and a narrow emission linewidth of 25 nm. It is interesting that, the composite has excellent stability, including water stability without attenuation of fluorescence intensity after soaking in water for 60 days, thermal stability of 120°C heating–cooling cycle, and excellent optical stability without attenuation under continuous ultraviolet irradiation.