Excitation‐, Temperature‐, and Time‐Dependent Color‐Changing Luminescent Organic–Inorganic Hybrid Metal Halide

ABSTRACT Luminescent materials play a prominent role in anti‐counterfeiting and information encryption. Most luminescent materials can only achieve specific emission colors, while reports on materials with dynamic luminescence responses are rare. Here, a novel Sb 3+ ‐doped zero‐dimensional (0D) organic–inorganic hybrid metal halide (OIHMH), ETP 2 HfCl 6 , is reported, which can simultaneously achieve dynamic color‐changing luminescence under different excitation wavelengths, different temperatures, and time‐dependent conditions. By tuning the excitation wavelength (270–370 nm), the emission color continuously changes from pink‐white to orange‐red. By varying the temperature from 100 to 490 K, the emission color changes from pink‐purple to orange‐red. Under ultraviolet (UV) excitation and after turning it off, the material changes from orange fluorescence to green phosphorescent emission. These phenomena are attributed to the bimodal emission characteristics of ETP 2 HfCl 6 :Sb 3+ , consisting of an organic emission peak at around 490 nm and an Sb 3+ self‐trapped exciton (STE) emission peak at around 642 nm, where the ratio of the two peaks is regulated by excitation wavelength, temperature, and time, thereby generating different emission colors. Exploiting this synergistic triple‐mode tunability, we successfully demonstrate multi‐level information encryption and dynamic anti‐counterfeiting patterns with high security.