Tunable photoluminescence of hybrid copper(I)-based halide single crystals achieved through halogen atom substitution

Low-dimensional hybrid Cu(I)-based halide materials are a new class of materials with low toxicity and excellent photoluminescent properties. In this work, five novel single crystals of [1,4-BDA]Cu 2 X 4 (X = Cl, Br, I) (1,4-BDA: 1,4-butanediamine) and [1,3-PDA] 2 Cu 3 X 7 (X = Cl, Br) (1,3-propanediamine) were obtained using a solvent evaporation method. The [1,4-BDA]Cu 2 X 4 (X = Cl, Br, I) crystals all have 1D structures, while the [1,3-PDA] 2 Cu 3 X 7 (X = Cl, Br) crystals have 0D structures. All five single crystals exhibit broadband blue emissions under 254 nm UV excitation at room temperature. Interestingly, both crystals show a gradual blueshift of the emission peaks with increasing halogen atomic mass, realizing tunable emission from the dark blue to sky blue range. The energy transfer process of the [1,4-BDA]Cu 2 Br 4 single crystal was studied using temperature-dependent photoluminescence spectroscopy. Combined with density-functional theory calculations, the reason for the shift of the PL emission peaks is explained. Notably, by altering the chemical composition, different photoluminescent halide materials can be obtained. Providing insight into the discovery of new low-toxicity, low-cost Cu(I)-based halide materials.