Heterovalent Doping in CsCdCl3 Enabled Tunable Multimode Luminescence and Photochromism Toward Multilevel Anti‐Counterfeiting

Abstract Integrating self‐trapped excitons (STEs), dopants, and defect levels in a single‐component metal halide perovskite will be of significance for tunable multimode luminescence and photochromism. Here, a platform utilizing interactions of STEs, defects, and alien dopants in CsCdCl 3 by a heterovalent doping strategy is demonstrated, in which the photoluminescence quantum efficiency is improved, and more importantly, the emissions can be manipulated statically and dynamically by dopants and changing excitation wavelength/irradiation time. Meanwhile, the presence of carrier trapping and de‐trapping processes leads to bright orange–near‐infrared persistent luminescence and photochromic behaviors, which can be quickly erased by white light, enabling visual displays and codable in dark and bright dual‐fields. Inspired by these versatile optical characteristics of doped luminescent metal halides, a multilevel encryption and anti‐counterfeiting platform with the advantages of nondestructive and convenient authentication is constructed.