The deposition and the optical characteristics of Cu-based metal halide Cs₃Cu₂I₅ thin film via mist deposition

Cu-based metal halides, such as Cs 3 Cu 2 I 5 , are promising materials for LEDs, photodetectors, and scintillators because of their excellent optical properties, nontoxicity, and high air stability. In this study, we demonstrated the deposition of high-coverage Cs 3 Cu 2 I 5 thin films using solution-based mist deposition. By adjusting the substrate temperature appropriately, continuous Cs 3 Cu 2 I 5 thin films were formed. The Cs 3 Cu 2 I 5 thin films exhibited blue emission under ultraviolet irradiation, with a large Stokes shift of 1.40 eV. Furthermore, they exhibited a high photoluminescence quantum yield of over 80%.