Phase control in the synthesis of cesium copper iodide compounds for their photoluminescence and radioluminescence study

Lead-free metal halide perovskites have attracted much attention owing to their non-toxicity and excellent optical properties. Especially, cesium copper iodide compounds exhibit advantages of good environmental stability and low cost, rendering promising potential applications in optoelectronic devices field. Here, we use an anti-solvent assisted crystallization method to realize phase control syntheses of CsCu₂I₃ and Cs₃Cu₂I₅ by varying the concentrations of precursor solution. Using high precursor solution concentrations, Cs₃Cu₂I₅ with strong blue emission peak at 440 nm is prepared. While the CsCu₂I₃ is fabricated at low precursor solution concentrations, with the yellow emission peak of 580 nm. Furthermore, the UV-pumped light-emitting diodes (UV-LEDs) are realized by adopting CsCu₂I₃ and Cs₃Cu₂I₅ powders as phosphors, and we also obverse the scintillation characteristic of the cesium copper iodide powders, showing potential applications for lighting and X-ray detection devices.