Low-Temperature Molten Salts Synthesis: CsPbBr₃ Nanocrystals with High Photoluminescence Emission Buried in Mesoporous SiO₂

Using mesoporous SiO₂ to encapsulate CsPbBr₃ nanocrystals is one of the best strategies to exploit such materials in devices. However, the CsPbBr₃/SiO₂ composites produced so far do not exhibit strong photoluminescence emission and, simultaneously, high stability against heat and water. We demonstrate a molten-salts-based approach delivering CsPbBr₃/mesoporous-SiO₂ composites with high PLQY (89 ± 10%) and high stability against heat, water, and aqua regia. The molten salts enable the formation of perovskite nanocrystals and other inorganic salts (KNO₃-NaNO₃-KBr) inside silica and the sealing of SiO₂ pores at temperatures as low as 350 °C, representing an important technological advancement (analogous sealing was observed only above 700 °C in previous reports). Our CsPbBr₃/mesoporous-SiO₂ composites are attractive for different applications: as a proof-of-concept, we prepared a white-light emitting diode exhibiting a correlated color temperature of 7692K. Our composites are also stable after immersion in saline water at high temperatures (a typical underground environment of oil wells), therefore holding promise as oil tracers.