Ultra‐Thermostability of Spatially Confined and Fully Protected Perovskite Nanocrystals by In Situ Crystallization

Abstract Although all‐inorganic perovskite materials present multiple fascinating optical properties, their poor stability undermines their potential application in the field of multi‐color display. Herein, spatially confined CsPbBr₃ nanocrystals are in situ crystallized within uniform mesoporous SiO₂ nanospheres (MSNs) to regulate their size distribution, passivate their surface defects, shield them from water/oxygen, and more importantly, enhance their thermotolerance. As a result, the remnant PL intensity of the prepared spatially confined perovskite (CsPbBr₃) nanocrystals by in situ crystallization within uniform mesoporous SiO₂ nanospheres (SCP@MSNs) powders can be maintained over 98% of its initial value even after being immersed in harsh conditions (0.1 m HCl or 0.1 m NaOH) for 60 days. Furthermore, the prepared SCP@MSNs‐PDMS film demonstrates astonishing thermostability by maintaining almost consistent room temperature PL intensities after continuous heating–cooling cycles between 200 and 25 °C, which would greatly improve its processability during potential industrial manufacturing. The fabricated LCD backlit based on SCP@MSNs covers 124% of NTSC standard and 95.6% of Rec. 2020 standard, indicating its great potential in practical display field.