Abstract
In this work, we describe a highly efficient and reabsorption-free X-ray-harvesting system using luminescent metal-organic framework (MOF)-fluorescence chromophore composite films. The ultrafast time-resolved experiments and density functional theory calculations demonstrate that a nearly 100% energy transfer from a luminescent MOF with a high atomic number to an organic chromophore with thermally activated delayed fluorescence (TADF) character can be achieved. Such an unprecedented efficiency of interfacial energy transfer and the direct harnessing of singlet and triplet excitons of the TADF chromophore led to remarkable enhancement of radioluminescence upon X-ray radiation. A low detection limit of 256 nGy/s of the fabricated X-ray imaging scintillator was achieved, about 60 times lower than the MOF and 7 times lower than the organic chromophore counterparts. More importantly, this detection limit is about 22 times lower than the standard dosage for a medical examination, making it an excellent candidate for X-ray radiography.
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•Metal-organic framework for X-ray imaging applications•Efficient energy transfer at the interface of the metal-organic framework•Energy transfer enabled good X-ray imaging resolution and low detection limit
High-performance scintillators are almost exclusively limited to ceramic and perovskite materials, which are typically prepared under harsh conditions or with poor air and light stability along with high toxicity and significant light reabsorption. In contrast, organic scintillators exhibit good processability and stability, but their low imaging resolution and detection sensitivity due to the limited effective atomic number significantly impede their practical applications. In this work, we address these great challenges through a highly efficient (nearly 100%) energy transfer strategy using a composite film of newly synthesized metal-organic frameworks and thermally activated delayed-fluorescence organic chromophores. With this new design, we successfully achieved reabsorption-free X-ray imaging scintillators with good imaging resolution and a low detection limit along with high air and light stability.
A high-performance X-ray imaging scintillator was successfully fabricated using an efficient energy transfer strategy between a luminescent metal-organic framework (MOF) and an organic emitter. This finding not only provides a new design principle for fabricating stable, reabsorption-free, and low-cost X-ray imaging scintillators along with an excellent performance, but also expands inorganic scintillators to MOF-chromophore nanocomposite films as a promising new alternative.