Zero-Dimensional Hybrid Cuprous Iodide Clusters for X-ray Imaging

Metal halide clusters have recently emerged as promising scintillators for X-ray detection and imaging owing to their high X-ray absorption coefficients, excellent environmental stability, and tunable luminescence. Here, we report two zero-dimensional (0D) hybrid cuprous iodide clusters, (4-popy)₄Cu₂I₂ and (4-popy)₄Cu₄I₄ (4-popy = 4-phenoxypyridine, C₁₁H₉NO), featuring isolated [Cu₂I₂] rhomboid dimers and [Cu₄I₄] cubane tetramers for X-ray detection and imaging. Due to the unique 0D configurations, both clusters exhibit broadband emissions, large Stokes shifts, and near-unity photoluminescence quantum yields. Notably, the (4-popy)₄Cu₄I₄ clusters, benefiting from their higher effective atomic number and denser framework, demonstrate an exceptional X-ray light yield of 52,000 photons·MeV^-1. Embedded into a poly(vinyl alcohol) matrix, flexible scintillation films based on (4-popy)₄Cu₄I₄ clusters achieve a low X-ray detection limit of 167 nGy·s^-1 and a high spatial resolution of X-ray imaging up to 20 lp·mm^-1. These results establish hybrid cuprous iodide clusters as a promising class of solution-processable and high-performance scintillators for low-dose, high-resolution X-ray imaging.