Zero-dimensional antimony halides with tunable photoluminescence via halogen ligand modulation

Organic-inorganic metal halides are undergoing booming development in terms of their diverse structures and attractive optical performances, summoning the exploration of the structure-property relationship of such materials. Herein, we report two luminescent metal halides, [AVIm](3)SbCl6 and [AVIm](3)SbBr6 (AVIm = 1-allyl-3-vinylimidazolium cation), and investigate the effect of halogen ligands on their emission properties. The single crystals of the two compounds with different space groups were obtained at ambient temperature, where antimony halide complex anions were surrounded by organic cations to form 0D frameworks. Based on the self-trapped exciton (STE) mechanism, [AVIm](3)SbCl6 emitted yellow light at 535 nm, while [AVIm](3)SbBr6 exhibited orange emission with dual bands at 470 nm and 575 nm. When the halogen ligand altered from Cl- to heavier Br-, the increased orbital coupling accelerated the radiative transition process, leading to a shorter luminescence lifetime of [AVIm](3)SbBr6. In comparison, [AVIm](3)SbCl6 presented superior photophysical performances, combined with the excellent chemical and thermal stability, making it a suitable phosphor for white light-emitting diode (WLED) devices. This work reveals the differences in photoluminescence properties from the halogen ligand perspective, providing valid insight into highly emissive antimony halides.