In Situ Growing of Inner BaPbP 2 O 7 Shell to Construct Efficient and Stable Perovskite Composites Using Ionic Aqueous Solution for WLED and Display

ABSTRACT Perovskite quantum dots (PeQDs) have garnered widespread attention due to their remarkable optical properties, yet their poor stability limits practical applications. Embedding PeQDs within mesoporous silica is one of the effective strategies to enhance their stability, but cannot effectively passivate the surface defects of PeQDs, resulting in relatively low photoluminescence quantum yield (PLQY) and significant photoluminescence quenching under light irradiation and heating. Herein, we report an innovative structure of growing an BaPbP 2 O 7 shell between CsPbBr 3 QDs and hollow mesoporous silica (HMS), using ionic aqueous solution under high temperature and pressure conditions. Effective passivation of surface defects is achieved through the combination of phosphate ions with B‐site cations on the perovskite surface. The resulting CsPbBr 3 /BaPbP 2 O 7 /HMS composites that feature surface passivation of BaPbP 2 O 7 and HMS encapsulation, demonstrating significantly improved PLQY from 29 ± 1% to 96 ± 1% and impressive resistance to adverse conditions such as water, heat, and blue light irradiation. Finally, CsPbBr 3 /BaPbP 2 O 7 /HMS are packaged as the emitting layer to construct a white light‐emitting diode with the chromaticity coordinates of (0.281, 0.345), showing good operating stability. Furthermore, images displayed on perovskite‐based liquid crystal displays with a wide color gamut covering 134% of the NTSC standard are more vivid and saturated.