Thermally Activated Delayed Fluorescence Hybrid Copper(I) Iodide Scintillator for Fast Neutron and X-ray Imaging.

Developing high-performance dual imaging applications, such as fast neutron and X-ray applications, using a single material presents a very significant challenge across chemistry, material science, physics, and engineering. Integrating both imaging capabilities into a single material for specialized detection applications will simplify device design and significantly reduce overall detection costs. This work represents the first demonstration of a lead-free system designed for high-performance dual imaging applications. It features a multifunctional hybrid copper(I) iodide scintillator, in which hydrogen-rich and luminescent units are synergistically coupled at the molecular level, enabling the simultaneous imaging of fast neutrons and X-rays. The perfect synergy of exciton confinement and thermally activated delayed fluorescence (TADF) effects empowers this material with exceptional dual imaging capabilities. The confined structure formed by heavy-atom modules at the core imparts a high exciton binding energy, suppressing the nonradiative recombination of excitons. The TADF mechanism channels phonons generated by high-energy radiation into the radiative recombination process. Additionally, the lack of self-absorption guarantees efficient photon utilization. Leveraging these properties, the material achieves an impressive X-ray light yield of approximately 42,000 photons/MeV and an exceptional spatial resolution of 25.8 lp/mm for X-ray imaging, surpassing most commercial scintillators available in the X-ray market. Furthermore, the material demonstrates an outstanding spatial resolution of 1.47 lp/mm in fast neutron imaging, representing the best level reported to date for a Pb-free scintillator. This environmentally friendly and high-performance multifunctional scintillator significantly advances next-generation scintillation materials, presenting exciting opportunities for high-precision and dual imaging applications at a low cost.