High Pressure Restrains the Photo-Induced Polyhedra Distortion in 0D Antimony-Based Metal Halide

Recently, dual emission phenomena based on excitation-dependent emission are increasingly observed in 0D antimony-based metal halides. However, the origins of these two emissions remain debated. Herein, high pressure is employed to investigate the structural-optical relationship of the typical 0D antimony-based metal halides (TTA)₂SbCl₅ (TTA = tetraethylammonium) and uncover mechanisms behind its emission. As pressure increases, the dual emission of (TTA)₂SbCl₅ under 303 nm excitation, characterized by high energy and low energy emission peaks, transitions to a single low energy emission peak at ≈5.7 GPa. Meanwhile, a single broadband emission peak excited by 355 nm maintains a distinct low energy emission peak throughout the compression process, exhibiting an excitation-dependent emission color response. Combining experiment results with density functional theory calculations, the observed phenomenon is attributed to pressure restrain of photo-induced distortion in the [SbCl₅]²⁻ polyhedra in (TTA)₂SbCl₅. These finding reveals the relationship between the local structure and excitation-dependent emission, providing new perspectives and insights into the modulation of Sb-based metal halides.