Blue-excited Broadband Near-infrared Emission from Zero-dimensional Organic-inorganic Hybrid Metal Halides

Luminescent metal halides have garnered significant attention due to their tunable emission characteristics and exceptional optoelectronic properties. Nevertheless, achieving metal halides that exhibit near-infrared (NIR) emission upon blue-light excitation remains a significant challenge. In this study, blue-light-induced NIR emission was successfully realized in the zero-dimensional (0D) (BTP)ZnBr:Sb single crystal [BTP:(3-Bromopropyl) triphenylphosphonium cation] via a straightforward energy transfer from the host (BTP)ZnBr to the self-trapped exciton (STE) state generated by Sb. Upon excitation with blue light, (BTP)ZnBr:12.5 % Sb exhibits broad NIR emission characterized by a peak at approximately 725 nm, a Stokes shift of about 295 nm, and a notably large full width at half maximum (FWHM) of 179 nm. Additionally, the analysis of experimental data in conjunction with density functional theory (DFT) calculations elucidated the blue light emission mechanism of the host as well as the doped NIR emission. The study demonstrated potential night vision applications by utilizing the (BTP)ZnBr:12.5 % Sb phosphor combined with a 430 nm light-emitting diode (LED) chip in the dark.