Thermally Activated Delayed Fluorescent Scintillators Based on Mononuclear Copper(Ⅰ) Halide Complexes for High-Resolution X-Ray Imaging

摘要

Scintillators have attracted tremendous attention due to their great potentialin radiation detection, industrial non-destructive testing, and medicaltheranostic applications. Thermally activated delayed fluorescence (TADF)based scintillators can simultaneously harvest radiation-induced singletand triplet excitons for high-efficient X-ray excited luminescence. However,pure organic TADF materials composed of light elements exhibit low X-rayabsorption coefficients, resulting in relatively weak X-ray excited luminescence.Herein, a series of novel high-performance X-ray scintillators basedon TADF mononuclear Cu(I)-halide complexes are successfully developed.Together with high X-ray absorption coefficient of heavy halogen elementsand halide-to-ligand charge transfer characteristics, these TADF scintillatorsdisplay excellent performance with high X-ray relative light yields (as high as28385 ± 1335 photons MeV~(?1)), good linear response to X-ray dose rate andhigh resistance to humidity and radiation. X-ray imaging tests show that arelatively high spatial resolution of 9.8 lp/mm is realized based on their flexiblescintillator films. These features suggest that it is a promising strategyto realize strong X-ray excited luminescence by incorporating heavy halogenelements in TADF materials, providing more possibilities for exploring newlow-cost and high-performance scintillators.