A Dual‐Regulation Strategy Enables Broadly Tunable Multiband Emission in Organic–inorganic Hybrid Rare Earth Halide Glass toward Dynamic Information Encryption

ABSTRACT Tunable multiband luminescence across a broad spectrum in a single transparent glass is highly desirable for advanced optoelectronics. However, this goal remains challenging in conventional inorganic glass systems, which are plagued by low doping concentrations of luminescent ions, and severe self‐absorption effects. Here, we report a dual‐regulation strategy by incorporating lanthanide ions (Ln 3+ ) into a novel organic–inorganic hybrid rare earth halide glass, Bzmim 3 YbCl 6 (Bzmim = 1‐benzyl‐3‐methylimidazolium, BYC). The resultant Bzmim 3 Yb 0.95 Ln 0.05 Cl 6 (BYC:0.05Ln; Ln = Eu 3+ , Tb 3+ , La 3+ , Gd 3+ , and Lu 3+ ) glasses achieve an order‐of‐magnitude enhancement in short‐wave infrared (SWIR) emission intensity. Furthermore, Tb 3+ and Eu 3+ co‐doped BYC glass exhibits excitation wavelength‐dependent photoluminescence. Notably, we have achieved, for the first time, unprecedented broadly tunable multiband luminescence in a single organic–inorganic hybrid metal halide (OIMH) glass, spanning the red, green, and blue (RGB) visible spectrum as well as the SWIR region. The unique optical properties, coupled with the material's recyclability and shape customizability, enable advanced applications in advanced anti‐counterfeiting and dynamic information encryption. The elucidated dual‐regulation mechanism—which concurrently suppresses concentration quenching and activates multiband emission—establishes a design paradigm for multifunctional luminescent glasses in next‐generation encryption technologies.