Hybrid Cuprous(I) Iodide Scintillator with Ultra-High Water Resistance for Underwater X-ray Imaging

Scintillators, the luminescent materials that convert high-energy radiation into photons with lower energy, act widely as the key component in X-ray imaging systems. The scintillators would typically have high light yield, low detection limit, as well as high environmental stability, which enables them to work in outdoor harsh environments. Herein, we report a novel one-dimensional hybrid copper(I) halide, N,N,N',N'-tetramethylethylenediamine copper(I) iodide ([TMEDA]Cu₂I₄). The bulk single crystals are obtained by solvent evaporation. The sample shows broadband blue emission under UV excitation, attributed to the emission of self-trapped excitonic states, with a photoluminescence quantum yield of nearly 30%. The material shows excellent water stability, virtually unaffected by 120 days of immersion in water under ambient conditions, and the water stability is credited to the structure with organic cations tightly wrapped around inorganic chains through weak hydrogen bonding to insulate water molecules. Working as a scintillator, [TMEDA]Cu₂I₄ shows a light yield of up to 14,400 photons/MeV. A scintillation film of more than 175 cm³ is fabricated with [TMEDA]Cu₂I₄ powder blended with poly(methyl methacrylate) (PMMA), showing both excellent water stability and excellent irradiation stability, enabling X-ray imaging under underwater conditions.