Achieving Near-Unity Red Light Photoluminescence in Antimony Halide Crystals via Polyhedron Regulation

Exploration of efficient red emitting antimony hybrid halide with large Stokes shift and zero self-absorption is highly desirable due to its enormous potential for applications in solid light emitting, and active optical waveguides. However, it is still challenging and rarely reported. Herein, a series of (TMS)₂SbCl₅ (TMS=triphenylsulfonium cation) crystals have been prepared with diverse [SbCl₅]^2- configurations and distinctive emission color. Among them, cubic-phase (TMS)₂SbCl₅ shows bright red emission with a large Stokes shift of 312 nm. In contrast, monoclinic and orthorhombic (TMS)₂SbCl₅ crystals deliver efficient yellow and orange emission, respectively. Comprehensive structural investigations reveal that larger Stokes shift and longer-wavelength emission of cubic (TMS)₂SbCl₅ can be attributed to the larger lattice volume and longer Sb⋅⋅⋅Sb distance, which favor sufficient structural aberration freedom at excited states. Together with robust stability, (TMS)₂SbCl₅ crystal family has been applied as optical waveguide with ultralow loss coefficient of 3.67 ⋅ 10^-4 dB μm^-1, and shows superior performance in white-light emission and anti-counterfeiting. In short, our study provides a novel and fundamental perspective to structure-property-application relationship of antimony hybrid halides, which will contribute to future rational design of high-performance emissive metal halides.