非铅双钙钛矿纳米晶-玻璃复合闪烁体的高分辨X射线成像研究

The exploration and development of scintillators for X-ray imaging has always been an important research topic. In recent years, metal halide perovskites have become the most promising new generation of scintillator materials due to their high X-ray absorption capacity, fast light attenuation, low cost and easy preparation. Currently, the most high-profile metal halide perovskite scintillators are lead-based. However, the low light yield, high biological toxicity and phase instability greatly limit their application in high-end X-ray imaging. To this end, this project intends to select halide double perovskite as the research object, which is the most stable phase in lead-free perovskites. To optimize the carrier transport process, the mechanism of action between X-ray and lead-free halide double perovskite scintillator will be clarified. Further, combined with glass-ceramic preparation technology, the lead-free halide double perovskite nanocrystal-glass composite scintillator with high light yield, fast light decay, high transmittance and high stability will be obtained. Finally, X-ray imaging with low radiation dose, high resolution and high imaging speed will be achieved. The implementation of this project is expected to unfold huge potentials to explore scintillators beyond lead halide perovskites for X-ray imaging and lay the foundation for the development of high-quality, high-stability X-ray scintillation screens and X-ray imaging technology.

用于X射线成像的闪烁体的探索和开发一直是一项重要的研究课题。近年来，金属卤化钙钛矿由于其高的X 射线吸收能力、较快的辐射发光速率、低成本及简单易制备等特点成为最有应用前景的新一代闪烁体材料。目前，最受瞩目的金属卤化钙钛矿闪烁体均为铅基，但其强的自吸收效应、较低的光产额、相不稳定性及生物毒性极大地限制了其在实际X射线成像中的应用。为此，本项目拟选择非铅体系中物相最为稳定的卤化双钙钛矿作为研究对象，研究非铅卤化双钙钛矿闪烁体在X射线下的发光机理，优化X射线转换效率，并结合微晶玻璃制备技术，获得高光子产额、快衰减、高光透、高稳定的非铅卤化双钙钛矿纳米晶-玻璃复合闪烁体，最终实现低辐射剂量、高成像分辨率、高成像速度的X射线成像。本项目的实施可以开拓非铅卤化钙钛矿类闪烁体用于X射线成像的新领域，对高质量、高稳定性的X射线闪烁屏的开发和X射线成像技术的发展具有重要意义。

X射线成像技术在医学诊断、国防安检及工业无损检测等众多领域有着重要的应用，作为间接型X射线成像系统的核心部件——闪烁体的探索和开发一直是一项重要的研究课题。针对新型金属卤化钙钛矿闪烁体的强自吸收、低光产、相不稳定及生物毒性等缺陷，本项目提出研究大斯托克斯位移的非铅类闪烁体，通过结构、组分的设计调控，获得了多种高效闪烁体，并系统分析了不同类型闪烁体在X射线下的发光机理、辐射发光特性、辐照稳定性以及X射线成像性质等。研究得到六例高效发光的锰基卤化物，其中一例稀有五配位的锰配合物光致发光效率高达95%，斯托克斯位移超过100 nm，并实现基于该系列有机-无机杂化金属锰配合物的X射线探测与成像；通过探究稀土氟化物纳米晶体和有机弹性基质间的作用机制，实现了高质量柔性闪烁体薄膜的可控制备，该闪烁体薄膜透过率超过90%，其X射线成像分辨率高达18.6 lp/mm；此外，我们首次将磺酸基MOF用于X射线探测研究，系统分析了有机配体和稀土离子间的能量转换机理，该类闪烁体展现出优异的辐照稳定性和X射线响应灵敏度。本项目的研究成果为发展高质量非铅类闪烁体及高分辨闪烁体屏提供了新方案。