Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Material, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou, 510006, China.
SZU-NUS Collaborative Innovation Center, ICL 2DMOST, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen, 518060, China.
Adv Sci (Weinh). 2023 May;10(15):e2207004. doi: 10.1002/advs.202207004. Epub 2023 Mar 22.
Scintillating materials that convert ionizing radiation into low-energy photons hold great potential for radiation detection, nondestructive inspection, medical radiography, and space exploration. However, organic scintillators are characterized by low radioluminescence, while bulky inorganic scintillators are not suitable for the development of flexible detectors. Here, high-resolution X-ray imaging using solution-processable lanthanide-based metal-organic frameworks as microscale scintillators is demonstrated. Mechanistic studies suggest that lanthanide ions absorb X-rays to generate high-density molecular triplet excitons, and excited linkers subsequently sensitize lanthanide ions via nonradiative resonance energy transfer. Furthermore, the crystalline nature offers a delocalized electronic feature rather than isolated subunits, which enables direct trapping of charge carriers by lanthanide emitters. By controlling the concentration ratio between Tb and Eu ions, efficient and color-tunable radioluminescence of lanthanide ions can be achieved. When coupled with elastic, transparent polymer matrices, these metal-organic framework-based microscintillators allow the fabrication of flexible X-ray detectors. Such detectors feature a detection limit of 23 nGy s , which is 240 times lower than the typical radiation dose for medical diagnosis. X-ray imaging with resolution higher than 16.6 line pairs per millimeter is further demonstrated. These findings provide insight into the future design of hybrid scintillators for optoelectronics and X-ray sensing and imaging.
闪烁材料将电离辐射转化为低能量光子，在辐射探测、无损检测、医学放射照相和太空探索方面具有巨大潜力。然而，有机闪烁体的辐射发光效率较低，而体积庞大的无机闪烁体不适合开发柔性探测器。在此，展示了使用可溶液加工的镧系金属-有机骨架作为微尺度闪烁体进行高分辨率 X 射线成像。机理研究表明，镧系离子吸收 X 射线产生高密度分子三重态激子，受激配体随后通过非辐射共振能量转移敏化镧系离子。此外，晶体性质提供了非定域的电子特性，而不是孤立的亚基，这使得电荷载流子可以被镧系发射器直接捕获。通过控制 Tb 和 Eu 离子的浓度比，可以实现镧系离子的高效且可调色彩的辐射发光。将这些金属-有机骨架基微闪烁体与弹性透明聚合物基质结合，可以制造出柔性 X 射线探测器。这种探测器的探测极限为 23 nGy·s，比医学诊断的典型辐射剂量低 240 倍。进一步展示了分辨率高于 16.6 线对/毫米的 X 射线成像。这些发现为光电和 X 射线传感与成像的混合闪烁体的未来设计提供了思路。
