Achieving\nBright Luminescence and X‑ray Scintillation\nin Zero-Dimensional Cesium Zinc Bromides by Cu<sup>+</sup>–Mn<sup>2+</sup> Codoping

Zero-dimensional (0D) metal halides have emerged as excellent\nluminescent\nmaterials for optical and optoelectronic applications. Especially\nenvironmentally friendly ternary zinc halides have recently drawn\nincreasing attention. Herein, we present the codoping of Cu<sup>+</sup> and Mn<sup>2+</sup> ions into 0D Cs<sub>2</sub>ZnBr<sub>4</sub> single\ncrystals (SCs), which show bright PL emission and high stability.\nAdjusting the Cu<sup>+</sup>/Mn<sup>2+</sup> ratio can make the photoluminescence\nquantum yield (PLQY) exceed 90%, which is much higher than that of\nthe single-ion doped sample. The efficient PL is determined by a combination\nof Cu<sup>+</sup>–Mn<sup>2+</sup> competitive interaction,\nCu<sup>+</sup>–Mn<sup>2+</sup> energy transfer, and Cu<sup>+</sup>–Mn<sup>2+</sup> synergistic passivation. More interestingly,\nthe codoped sample shows a better scintillation performance with a\nlow detection limit of 52 nGy<sub>air</sub>/s and a sensitive spatial\nresolution of 13.2 lp/mm. We further explore the promising applications\nof Cu<sup>+</sup>–Mn<sup>2+</sup>-codoped Cs<sub>2</sub>ZnBr<sub>4</sub> SCs for anticounterfeiting and X-ray imaging. These results\nnot only help to grasp the excited-state photophysical processes of\n0D codoped metal halides but also provide a new way for the design\nand development of environmentally friendly luminescent materials.