Tunable Multicolor Emission and High Thermal Stability in Single‐Matrix Luminescent Crystals Based on Calcium Perovskites for Advanced Solid‐State Lighting Applications

Abstract The development of environmentally friendly full‐inorganic luminescent materials with tunable emission properties and exceptional thermal stability is of paramount importance for applications in optoelectronic devices, solid‐state lighting, and anti‐counterfeiting technologies. In this study, a novel luminescent crystal based on calcium perovskites Cs₂CaCl₄·2H₂O (CCCH) are explored using a hydrothermal method. Simultaneous co‐doping of CCCH with Sn²⁺ and Mn²⁺ yields the s‐p transition‐induced cyan light from Sn²⁺ and d‐d transition‐induced yellow light from Mn²⁺. It demonstrates effective energy transfer from self‐trapped exciton (STE) of matrix CCCH and s‐p transition of Sn²⁺ to Mn²⁺, synergizing composite white lights with tunable colors. Furthermore, the incorporation of Sn²⁺ into CCCH introduces a red shift from blue to cyan emission with a remarkable enhancement in luminescent intensity by a factor of 12 times. The crystal orbital Hamiltonian populations (─COHP) calculations revealed the crucial role of Mn²⁺ in lattice stability, as evidenced by the decomposition temperature exceeding 305 °C for CCCH:Sn²⁺,Mn²⁺ whereas 210 °C for undoped CCCH matrix. This research provides a comprehensive investigation of the luminescent properties of CCCH:Sn²⁺,Mn²⁺ crystal, holding significant promise for practical technological advancements in lighting and anti‐counterfeiting technologies.