Traditional smart fluorescent materials, which have been attracting increasing interest for security protection, are usually visible under either ambient or UV light, making them adverse to the potential application of confidential information protection. Herein, we report an approach to realize confidential information protection and storage based on the conversion of lead-based metal-organic frameworks (MOFs) to luminescent perovskite nanocrystals (NCs). Owing to the invisible and controlled printable characteristics of lead-based MOFs, confidential information can be recorded and encrypted by MOF patterns, which cannot be read through common decryption methods. Through our conversion strategy, highly luminescent perovskite NCs can be formed quickly and simply by using a halide salt trigger that reacts with the MOF, thus promoting effective information decryption. Finally, through polar solvents impregnation and halide salt conversion, the luminescence of the perovskite NCs can be quenched and recovered, leading to reversible on/off switching of the luminescence signal for multiple information encryption and decryption processes.

Achieving good stability while maintaining excellent properties is one of the main challenges for enhancing the competitiveness of luminescent perovskite CsPbX₃ (X=Cl, Br, I) nanocrystals (NCs). Here, we propose a facile strategy to synthesize ceramic-like stable and highly luminescent CsPbBr₃ NCs by encapsulating them into silica derived from molecular sieve templates at high temperature (600–900 ^oC). The obtained CsPbBr₃-SiO₂ powders not only show high photoluminescence quantum yield (~71%), but also show an exceptional stability comparable to the ceramic Sr₂SiO₄:Eu²⁺ green phosphor. They can maintain 100% of their photoluminescence value under illumination on blue light-emitting diodes (LEDs) chips (20 mA, 2.7 V) for 1000 h, and can also survive in a harsh hydrochloric acid aqueous solution (1 M) for 50 days. We believe that the above robust stabilities will significantly enhance the potential of perovskite CsPbX₃ NCs to be practically applied in LEDs and backlight displays.