Growth of CsPbX3 nanocrystals using sol–gel SiO2 solid powders as reactors without capping agents towards anomalous stable emission membranes

To overcome the poor stability of metal halide perovskite nanocrystals (NCs) prepared in organic solvents, a solid reaction method at high temperature was developed using sol–gel porous SiO 2 as a reactor. Sol-gel SiO 2 powders were used to encapsulate CsPbX 3 NCs at high temperatures (600–800 °C) in air to get SiO 2 /CsPbX 3 glass by dispersing growth cites in advance and no ligands added. After NaOH etching, a thin dense SiO 2 shell was remained on the surface of CsPbX 3 NCs (named as CsPbX 3 @SiO 2 ).The photoluminescence (PL) quantum yield of the CsPbX 3 @SiO 2 was 86.7 %, in which their PL peak wavelengths were adjusted from 410-707 nm by changing halogen components. The dense SiO 2 shell on CsPbX 3 NCs blocked the connection of CsPbX 3 cores with water and oxygen in the external environment, resulting in CsPbX 3 @SiO 2 revealed extraordinary high stability. After immersing in water for half year, the PL intensity of CsPbX 3 @SiO 2 composites was remained unchanged and the composites still revealed bright PL after heat-treating in boiling water for 14 h. These highly stable composites were used to fabricate a white light-emitting diode, in which the color coordinates are located at (0.36, 0.33), and the color temperature reaches 5169 K which belongs to the warm white light range.