Internal–External Stabilization Strategies Enable Ultrastable and Highly Luminescent CsPbBr3 Perovskite Nanocrystals for Aqueous Fe3+ Detection and Information Encryption

Abstract The high photoluminescence quantum yield (PLQY) of perovskite nanocrystals (PNCs) makes them promising candidates in optoelectronics. However, the easy loss of structural integrity and fast chemical degradation upon exposure to moisture influence their reliable applications in aqueous solutions. Here, a hierarchical surface construction strategy is rationally designed to fulfill an internal–external stabilization of PNCs. Carbon quantum dots (CQDs) and cetyltrimethyl ammonium bromide (CTAB) have been demonstrated stabilized PNCs internally by eliminating the proton transfer‐induced ligand desorption. Meanwhile, CTAB acts as a cationic surfactant in consolidating the subsequent SiO 2 coating to prevent the PNCs from external environments. Based on the resulted PNCs, a sensitive and selective fluorescence film sensor for Fe 3+ detection is successfully constructed. The fluorescence of PNCs at 525 nm is quenched after the addition of Fe 3+ in the concentration range from 770 p m to 411 µ m . As Fe 3+ ions attached to the surface of the film are removed with water, the fluorescence of the film can be easily recovered. Owing to this character, the application of the PNCs toward the confidential information encryption has been proved. This work provides an effective design strategy to improve the stability of PNCs and extends their applications in sensing and encryption areas.