Aqueous grinding synthesis of high-performance alkali/alkaline earth metal-tuned copper(I) iodide cluster scintillators for underwater x-ray imaging

Cu(I) halides have emerged as promising scintillator candidates for underwater x-ray imaging applications, owing to their exceptional stability in water environment and outstanding optical properties. However, the reliance on toxic organic solvents and low production yield in conventional synthesis methods pose obstacles to practical application. In this work, an aqueous grinding method is presented for the efficient synthesis of Cu(I)-iodine cluster halides powder (C₁₂H₂₄O₆)₂X₂Cu_mI_n (XCuI, X represents different alkali metals or alkaline earth metals), which exhibits bright luminescence with a high photoluminescence quantum yield (PLQY). The proposed approach is characterized by its simplicity, cost-effectiveness, environmental friendliness and safety. Given its high PLQY of 95.86% and rich photophysical properties, the scintillation performance of NaCuI is systematically investigated. The NaCuI powder achieves a low detection limit of 54.8 nGy_air s⁻¹ and a high relative light yield of 61 986 photons MeV⁻¹. Building upon these foundations, we fabricated a large-area and highly flexible NaCuI scintillation screen, which achieves an outstanding spatial resolution of 10.84 lp mm⁻¹. Furthermore, integration of the scintillator screen with a thin-film transistor backplane array enabled real-time digital imaging of various test objects. The resulting x-ray flat-panel detector demonstrated exceptional imaging performance, capturing well-defined contours of imaged subjects and remarkably detecting underwater objects with notch defects. This research provides a new strategy for the synthesis and application of highly efficient luminescent scintillators with low-cost, high yield, and environmental friendliness. (Figure presented.).