A Mild Synthesis of 0D Mn²⁺‐Doped Cs₃CdBr₅ Metal Halide for White Light‐Emitting Diodes and X‐Ray Imaging

Abstract All‐inorganic Cd‐based metal halide is widely studied and applied in the field of optoelectronics due to its superior stability, diverse phase structure, and unique photoelectric properties. However, all‐inorganic 0D Cd‐based metal halide is not widely studied due to their extreme synthesis conditions. In this paper, a simple mild solution method is devised to successfully synthesize 0D Cs 3 CdBr 5 by manipulating the crystal growth kinetics. Simultaneously, the influence of the doping element Mn on the transition matrix and the optical properties are investigated. By doping with an appropriate concentration of Mn 2+ , a green emission (520 nm) with photoluminescence quantum yield (PLQY) as high as 97.39% is obtained. Benefiting from near‐unity PLQY and the excellent optical properties, the white emitting light‐emitting diodes (WLEDs) with Cs 3 CdBr 5 :20%Mn as green phosphor exhibit warm white light emission with color rendering index (CRI) of 91 and correlated color temperature (CCT) of 4108 K. In addition, Cs 3 CdBr 5 :20%Mn also demonstrates excellent X‐ray scintillation properties with a low detection limit of 32.83 nGy air ·s −1 . The results show that Cs 3 CdBr 5 :Mn is not only a promising candidate for solid‐state lighting but also a promising candidate for low‐dose high‐resolution X‐ray imaging.