Rapid synthesis and mechanochemical reactions of cesium copper halides for convenient chromaticity tuning and efficient white light emission

Abstract

Lead halide perovskites are emerging as important candidates for many photoelectric applications; however, the toxicity of the heavy metal Pb poses a barrier to such applications. Thus, intense research efforts have been directed to developing lead-free photoelectric materials. Here, we report on the synthesis and transformation of the cesium copper halides Cs₃Cu₂I₅ and CsCu₂I₃. These Cu based halide compounds are synthesized through a rapid antisolvent crystallization process with the use of isopropanol. The Cs₃Cu₂I₅ has blue emission at 445 nm with a full width at half maximum (FWHM) of ∼81.7 nm; CsCu₂I₃ has a yellow emission at 575 nm with a FWHM of ∼119.9 nm. Notably, these two compounds can be interconverted through mechanochemical reactions. Therefore, standard white light emission can be obtained from a mixture of these two halides at an appropriate ratio and a white light emitting diode device is fabricated. We report a convenient route for rapid synthesis and easy tuning of Commission Internationale de l’Eclairage chromaticity coordinates to achieve white light emission. These findings might promote the large-scale synthesis of lead-free all-inorganic compounds for future applications in optoelectronic devices.