Achieving Bright Luminescence and X-ray Scintillation in Zero-Dimensional Cesium Zinc Bromides by Cu⁺-Mn²⁺ Codoping

Zero-dimensional (0D) metal halides have emerged as excellent luminescent materials for optical and optoelectronic applications. Especially environmentally friendly ternary zinc halides have recently drawn increasing attention. Herein, we present the codoping of Cu⁺ and Mn²⁺ ions into 0D Cs₂ZnBr₄ single crystals (SCs), which show bright PL emission and high stability. Adjusting the Cu⁺/Mn²⁺ ratio can make the photoluminescence quantum yield (PLQY) exceed 90%, which is much higher than that of the single-ion doped sample. The efficient PL is determined by a combination of Cu⁺-Mn²⁺ competitive interaction, Cu⁺-Mn²⁺ energy transfer, and Cu⁺-Mn²⁺ synergistic passivation. More interestingly, the codoped sample shows a better scintillation performance with a low detection limit of 52 nGy_air/s and a sensitive spatial resolution of 13.2 lp/mm. We further explore the promising applications of Cu⁺-Mn²⁺-codoped Cs₂ZnBr₄ SCs for anticounterfeiting and X-ray imaging. These results not only help to grasp the excited-state photophysical processes of 0D codoped metal halides but also provide a new way for the design and development of environmentally friendly luminescent materials.