Photoluminescent Thermal Response Regulation in Zinc Metal Halide Materials Through Sn ²⁺ Alloying‐Induced Carrier Localization for Visualization‐Enabled Temperature Sensor

ABSTRACT Zero‐dimensional (0D) metal halides have garnered unprecedented research interest in sensing, anti‐counterfeiting, light‐emitting diodes, and other cutting‐edge fields, owing to their unique crystal structures and exceptional optical properties. However, substantial challenges still remain in elucidating their luminescent mechanisms and precisely regulating their optoelectronic properties. Herein, we design and synthesize a 0D metal halide temperature‐sensing material, Rb ₂ (Zn,Sn)Cl ₄ , which features stable sensing sensitivity and distinct temperature‐visualization capability. The host Rb ₂ ZnCl ₄ exhibits defect‐related blue photoluminescence under ultraviolet excitation. Alloying with Sn ²⁺ not only induces temperature‐sensitive broadband orange emission originating from self‐trapped exciton (STE) recombination but also remarkably enhances the thermal stability of defect‐derived luminescence. Combined analysis of density functional theory (DFT) calculations and temperature‐dependent luminescence decay curves verifies that Sn ²⁺ doping reinforces the electron localization at the conduction band bottom, which effectively suppresses the migration of excited electrons to luminescence‐quenching centers. This material displays a distinct color transition from orange to blue with increasing temperature and maintains a high and stable relative sensitivity (S _R ) of over 1.26% K ⁻¹ in the range of 20°C–100°C. These characteristics endow Rb ₂ ZnCl ₄ :Sn ²⁺ with great application potential in the field of optical temperature sensing.