Color-Tunable\nCsCdCl<sub>3</sub> Perovskite for Low-Temperature\nAnticounterfeiting and Information Storage Applications

Low-temperature anticounterfeiting technologies play\na crucial\nrole in ensuring the authenticity and integrity of temperature-sensitive\nproducts such as vaccines, pharmaceuticals, and food items. In this\nwork, a low-temperature anticounterfeiting route based on the differentiated\nphotoluminescence (PL), PersL, and thermally stimulated luminescence\n(TSL) behaviors of metal halide perovskite, pure CsCdCl<sub>3</sub>, and CsCdCl<sub>3</sub>:10% Te<sup>4+</sup> is proposed. The CsCdCl<sub>3</sub> host exhibits pronounced color shifts, encompassing PL, PersL,\nand TSL behaviors, ranging from blue to yellow and orange as the temperature\nrises from 100 K to room temperature. This color change is attributed\nto a change in the luminous center (from the D<sub>3d</sub> octahedron\nto the C<sub>3v</sub> octahedron). Conversely, the addition of Te<sup>4+</sup> as the luminescence center inhibits the matrix emission,\nmaintains the characteristic orange emission of Te<sup>4+</sup>, and\nregulates the trap distribution of the matrix at low temperature and\nthe TL luminescence intensity. This work highlights the significant\npromise of CsCdCl<sub>3</sub>:10% Te<sup>4+</sup> and CsCdCl<sub>3</sub> phosphors as innovative low-temperature anticounterfeiting technologies,\nespecially for cold-chain vaccine safety monitoring.