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 A2ZnCl4:Sb3+ (A = Rb, Cs) to achieve tunable NIR luminescence is reported. The prepared A2ZnCl4:Sb3+ (A = Rb, Cs) halides exhibited efficient broadband NIR emission, which originates from self-trapped excitons of the [SbCl4]− polyhedron. Based on the regulation of cation, the [SbCl4]− 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.