Novel green-emitting copper-doped Cs2ZnCl4 synthesized via low-temperature solid-state reaction using a small amount of water

Abstract

All-inorganic halides exhibit excellent optical as well as luminescence properties. Among them, non-toxic copper-doped halide Cs2ZnCl4 with high stability is a promising material. However, the conventional method for preparing these materials, using the hot injection technique, is unsuitable for mass production. Therefore, herein, we suggest a simple and low-temperature (below 100 °C) method without using special equipment, regents, and treatments. Cu-doped Cs2ZnCl4 was successfully synthesized using the water-assisted solid-state reaction (WASSR) method, and the oxidation state of Cu in the samples was estimated through the iodometric titration technique. The optical and luminescence properties were investigated using the absorption and photoluminescence excitation/emission spectra. Significantly, Cu-doped Cs2ZnCl4 exhibited unique green emission centered at 3520 nm under ultraviolet irradiation. Moreover, the oxidation of Cu in the Cs2ZnCl4 lattice was suppressed owing to the low-temperature conditions in the WASSR.