A Zero-Dimensional Zn(II)-Based Organic–Inorganic Hybrid Metal Halide with Blue-Green Emission for White Light-Emitting Diode Application

Organic–inorganic hybrid metal halides (OIMHs), especially zero-dimensional (0D) ones, have been recognized as an excellent class of luminescent materials due to their structural diversity and tunable emission properties. In this work, using the environmentally friendly Zn(II) ion as the central metal and 1,4,7,10-tetraazacyclododecane (Cyclen) as the organic component, we successfully synthesized a novel OIMH, (H3Cyclen)(ZnBr4)·Br·H2O. Single-crystal X-ray diffraction analysis reveals that (H3Cyclen)(ZnBr4)·Br·H2O possesses a 0D structure, in which the [ZnBr4]2− tetrahedra are uniformly separated by the organic amine cations. This structural feature is expected to enhance the material’s stability and optimize its optoelectronic properties. Under UV lamp irradiation, (H3Cyclen)(ZnBr4)·Br·H2O emits bright blue-green light. Therefore, we systematically investigated its luminescence properties. The emission mechanism was further elucidated using UV–vis absorption spectroscopy and DFT calculations. Finally, (H3Cyclen)(ZnBr4)·Br·H2O was employed as a luminescent material to fabricate a white light-emitting diode (WLED), demonstrating its potential as an excellent phosphor material.