Achieving Color‐Tunable Long Persistent Luminescence in Cs2CdCl4 Ruddlesden‐Popper Phase Perovskites

Abstract Two‐dimensional (2D)‐halide perovskites have been enriched over recent years to offer remarkable features from diverse chemical structures and environmental stability endowed with exciting functionalities in photoelectric detectors and phosphorescence systems. However, the low conversion efficiency of singlet to triplet in 2D hybrid halide perovskites reduces phosphorescence lifetimes. In this study, the long persistent luminescence of 2D all‐inorganic perovskites with a self‐assembled 2D interlayer galleries structure is investigated. The results show that the decay time of the long persistent luminescence increases from 450 s to 600 s, and the luminescence color changes from cyan to orange, and the thermal stability of photoluminescence enhances dramatically after replacing Cd 2+ by appropriate Mn 2+ ions in 2D Cs 2 CdCl 4 Ruddlesden‐Popper phase perovskites. Furthermore, diversified anti‐counterfeiting modes are fabricated to highlight the promising applications of Cs 2 CdCl 4 perovskite systems with tunable persistent luminescence in advanced anti‐counterfeiting. Therefore, our studies provide a novel model for realizing tunable long persistent luminescence of perovskite with 2D self‐assembled layered structure for advanced anti‐counterfeiting.