Highly luminescent and stable inorganic perovskite micro-nanocomposites for crucial information encryption and decryption

Externally stimulated fluorescent materials have attracted widespread attention in the field of information security, but there are few reports on reversible hydrochromic materials, and the photoluminescence quantum yields (PL QYs) of these materials are still low. Herein, we report a strategy for encrypting/decrypting crucial information with Cd2+ doped all-inorganic perovskite nanocrystals (PNCs) (Cd2+: CsPbX3, X = Cl, Br, I) anchored in magnesium silicate hollow spheres (MSHSs). The prepared Cd2+: CsPbX3-MSHSs micro-nanocomposites exhibit higher PL QYs due to the suppression of non-radiative decay and the enhanced radiative decay rate. Additionally, the layered structure of MSHSs limits the spatial distribution of PNCs, so the humidification/dehumidification process could result in optical signal reversible switching with high brightness and stability. We demonstrated that under the synergy of Cd2+ ions doping and magnesium silicate matrix encapsulation, the micro-nanocomposites not only possess excellent and repeatable hydrochromic property, but also display remarkable photostability and thermal stability, which can be used for encryption and decryption of crucial information.