Fabrication Of Thermally Activated Delayed Fluorescence Cuprous Halide Complex-based Scintillators For X-ray Imaging

Scintillators,with the ability to convert high-energy photons(e.g.,X-ray,γ-ray)into visible light,have attracted tremendous attention due to their great potential in radiation detections,industrial nondestructive testing and medical theranostic applications.However,almost all of commercial scintillator materials rely on costly bulk crystals and are grown by the Czochralski method under harsh preparation conditions,which is expensive to produce and is often accompanied by problems such as strong hygroscopicity,which greatly limits their practical application.In this regard,eco-friendly Cu(I)halide complexes are strongly motivated by their low cost,high structural diversity,high environmental stability,rich excited state properties and efficient luminescence behavior.Therefore,the design,preparation,luminescence performance control and Xray imaging of Cu(I)halide complexes scintillators are of great significance for expanding scintillator material systems and developing low-cost,high-resolution,low-dose and flexible compatible X-ray imaging techniques.The major research works are as follows:1.Design,synthesis and X-ray detection application of copper(I)halide complexes scintillators based on phosphonic nitrogen ligand.Aiming at the problems of harsh preparation conditions and strong hygroscopicity of existing commercial scintillator materials,we selected Cu(I)halide complexes with high environmental stability,low cost and rich excited state properties as the research objects.Two mononuclear copper(I)complexes and two dual-core complexes were synthesized by a simple solution reaction.The luminescence principle and structure-activity relationship of copper(I)complexes were explored by testing the photophysical properties of complexes.The excitation state properties,luminescence color and luminescence lifetime can be regulated by regulating the core structure of the copper(I)complex.The experimental results show that the Cu(I)complex scintillator material exhibits excellent radiative luminescence performance,and confirms the important role of thermal activation delayed fluorescence(TADF)process in scintillator radiation luminescence.Furthermore,the flexible scintillator film is obtained by a simple drip coating method,the scintillator film resolution and imaging performance test confirm that the obtained flexible scintillator film has good imaging ability and can achieve clear X-ray imaging.2.Design,synthesis and X-ray detection application of scintillators based on single-core copper(I)halide complexesScintillator materials with thermally activated delayed fluorescence(TADF)can capture both radiation-induced singlet and triplet excitons,enabling efficient X-ray excitation luminescence.However,pure organic TADF materials composed of light elements exhibit a low X-ray absorption coefficient,resulting in relatively weak X-ray excitation luminescence.In this chapter,we study the effects of heavy elements on X-ray luminescence and imaging performance by designing TADF mononuclear Cu(I)complexes containing different halogen atoms.The experimental results show that,the TADF mononuclear Cu(I)complex combines the high X-ray absorption performance of halogen atoms and make full utilization of singlet and triplet excitons induced by X-ray radiation,which result in excellent X-ray light yield,high spatial resolution and low detection limits.The research results fully show that the realization of strong X-ray excitation luminescence by doping heavy halogen elements into TADF materials is a promising strategy,which provides more possibilities for exploring new low-cost,environmentally friendly and high-performance scintillators.