Cage-like Organic Cation-Engineered 0D Hybrid Bromide [S3(CH2)4.5]2(SbBr6): Synthesis, Structure, and Photoluminescence and Radioluminescence Properties

Abstract Zero-dimensional (0D) organic–inorganic hybrid metal halides have attracted considerable attention for their exceptional luminescence properties. Guided by a design strategy that employs cage-like organic cations to spatially isolate inorganic luminescent centers for enhanced luminescence, a novel 0D hybrid metal bromide, [S3(CH2)4.5]2(SbBr6), has been successfully synthesized. Its structure is characterized by a typical 0D architecture, which is composed of discrete (SbBr6)3– octahedral anions and cage-like [S3(CH2)4.5]1.5+ cations. The compound exhibits bright yellow-green photoluminescence centered at 542 nm, attributed to self-trapped exciton (STE) emission, with a broad full-width at half-maximum (fwhm) of 115 nm, a large Stokes shift of 172 nm, and a remarkable photoluminescence quantum yield (PLQY) of 84.91%. Furthermore, [S3(CH2)4.5]2(SbBr6) demonstrates X-ray radioluminescence with an emission maximum at 538 nm and a high light yield of 21 050 photons MeV–1. Meanwhile, the [S3(CH2)4.5]2(SbBr6)@PVA composite film exhibits efficient X-ray imaging performance with a spatial resolution of 5 lp mm–1. These results highlight the effectiveness of utilizing cage-like organic cations in constructing high-performance 0D hybrid metal halide phosphors and scintillators.