Emission‐Color‐Tunable Pb−Sn Alloyed Single Crystals with High Luminescent Efficiency and Stability

Abstract Although multiple emissive materials are of great research interest due to their great potential in a variety of applications, it is still challenging to prepare highly luminescent color‐tunable phosphors. Herein, the authors report a series of Pb−Sn alloyed single crystals, (C₁₀NH₂₂)₂Pb_1−xSn_xBr₄ (x = 0 to 1), that are equipped with two independent self‐trapped excitons (STEs) emitters. Multicolor luminescent output from blue to red and white light can be obtained by tailoring the composition, excitation wavelength, temperature, or time gating. More importantly, the synergistic effect between PbBr₄²⁻ and SnBr₄²⁻ enables (C₁₀NH₂₂)₂Pb_1−xSn_xBr₄ to have an extremely high luminescent efficiency up to near unity and remarkably extends stability in ambient air, significantly outperforming the monometallic (C₁₀NH₂₂)₂PbBr₄ and (C₁₀NH₂₂)₂SnBr₄. As an encouraging result of the richly endowed emission property and robust stability, (C₁₀NH₂₂)₂Pb_1−xSn_xBr₄ is further employed in multifunctional applications including the luminescent radiometric thermometer, white light emitter, and high‐security anti‐counterfeit materials.