Near-Unity Energy Transfer from Triplet to Self-Trapped Excitons in Transparent Hybrid Metal Halide Glasses for High-Resolution X-ray Imaging

Hybrid metal halides are promising scintillators due to their strong X-ray absorption and efficient self-trapped exciton (STE) emission. However, their practical applications are largely hindered by poor processability, severe light scattering, and substantial energy loss during secondary electron relaxation, leading to low spatial resolution in X-ray imaging. Here, we report a solvent-assisted rapid evaporation method for fabricating a class of hybrid metal halide glasses with excellent processability and high optical transparency. A molecular design strategy is further introduced by incorporating triphenylphosphonium-based organic phosphorescent cations to effectively reclaim the energy dissipated during the relaxation of secondary electrons. In addition to the direct X-ray excitation of the inorganic STE state, the harvested triplet excitons can further sensitize STE emission with near-unity energy transfer efficiency. This dual-sensitization pathway synergistically enhances the scintillation performance. A large-area scintillation screen is successfully fabricated, achieving high-resolution X-ray imaging with a spatial resolution of 22.5 lp mm–1.