Tunable Dual-Band White Light Emission from Gua_3CuCl_4 and Gua_7Cu_3X_10·3DMF (X = Br, I)

Abstract

ll-inorganic copper(I) halides have recently emerged as attractive alternatives to lead-based halide perovskites and rare-earth-doped inorganics for light emission applications. Most of the newly discovered all-inorganic Cu(I) halides demonstrate high-efficiency blue emission albeit with unusually poor tunability of photoluminescence (PL) properties. This work reports the facile preparation of three new copper(I) halides based on the guanidinium cation: (CN3H6)3CuCl4, (CN3H6)7Cu3Br10·3(C3H7NO), and (CN3H6)7Cu3I10·3(C3H7NO). A comprehensive characterization of PL is presented for these novel materials, which have highly tunable, dual blue–yellow emission responsive to both excitation wavelength and vacuum annealing. These have remarkable photoluminescence quantum yield (PLQY) values of up to 34.6% and color-rendering indices (CRI) up to 97% for tunable, single-phase white light emission with correlated color temperatures (CCT) ranging from 4851 to 18 921 K, demonstrating the excellent potential of Cu(I) halides for light emission applications.