Antimony Doping in A2ZnCl4 (A= Rb, Cs) Metal Halides Enabling Tunable Near-Infrared Emission

Lead-free metal halides with stable and tunable emission have shown great promise for broad application prospects in the visible light range. However, it remains a fundamental challenge to realize tunable near-infrared (NIR) luminescence in these metal halide materials. Herein, a cation regulation strategy in zero-dimension organic metal halides A 2 ZnCl 4 :Sb 3+ (A = Rb, Cs) to achieve tunable NIR luminescence is reported. The prepared A 2 ZnCl 4 :Sb 3+ (A = Rb, Cs) halides exhibited efficient broadband NIR emission, which originates from selftrapped excitons of the [SbCl 4 ] - polyhedron. Based on the regulation of cation, the [SbCl 4 ] - tetrahedral distortion capacity changes, exciton -phonon coupling is enhanced, leading to a red shift of the emission wavelength. The results provide inspiration for the regulation of the self-trapped excitons luminescence of halides and demonstrate potential as a non-visible light source for night vision.