The development of materials with outstanding performance for sensitive and selective detection of multiple analytes is essential for the development of human health and society. Luminescent metal–organic frameworks (LMOFs) have controllable surface and pore sizes and excellent optical properties. Therefore, a variety of LMOF-based sensors with diverse detection functions can be easily designed and applied. Furthermore, the introduction of energy transfer (ET) into LMOFs (ET-LMOFs) could provide a richer design concept and a much more sensitive and accurate sensing performance. In this review, we focus on the recent five years of advances in ET-LMOF-based sensing materials, with an emphasis on photochemical and photophysical mechanisms. We discuss in detail possible energy transfer processes within a MOF structure or between MOFs and guest materials. Finally, the possible sensing applications of the ET-LMOF-based sensors are highlighted.

https://pubs.acs.org/doi/pdf/10.1021/acsami.1c24759

Energy Transfer in Metal–Organic Frameworks for Fluorescence Sensing

The weak X-ray capture capability of organic scintillators always leads to poor imaging resolution and detection sensitivity. Here, we realize an efficient and reabsorption-free organic scintillato...

Perovskite-Nanosheet Sensitizer for Highly Efficient Organic X-ray Imaging Scintillator

Flexible copper halide films of 400 cm2 area were fabricated with outstanding mechanical stability, excellent film uniformity, nearly 100% photoluminescence quantum yields, and resistance to water and heat. The re-absorption-free X-ray imaging scintillators engineered based on these films exhibit superior scintillation performance with a detection limit as low as 48.6 nGy/s and 17 lp/mm X-ray imaging resolution, representing the highest imaging resolution for powder-based screens. 

Large-Area Perovskite-Related Copper Halide Film for High-Resolution Flexible X-ray Imaging Scintillation Screens

Summary 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.

Nearly 100% energy transfer at the interface of metal-organic frameworks for X-ray imaging scintillators

Detecting hard X-rays and γ-rays with high energy resolution is critical for medical and industrial applications, high-energy fundamental physics, and homeland security. Two types of radiation detectors, indirect-conversion (scintillators) and direct-conversion (solid-state) detectors, are the most widely used technologies. Semiconductor-based detectors that can directly convert γ-rays into an electrical signal and operate at room temperature are especially important as portable and cost-efficient detectors with high sensitivity and energy resolution. Recently, lead halide perovskites have attracted enormous interest for γ-ray detection, and significant progress has been made toward practical detectors using perovskites as active materials. In this Review, we start with the fundamentals of γ-ray detection and review the recent developments in halide perovskite γ-ray detectors. The key factors affecting the detector performance are summarized. We also give an outlook on the field, with emphasis on the challenges to be overcome. 

Jian-Xin Wang

Papers

Perovskite-Nanosheet Sensitizer for Highly Efficient Organic X-ray Imaging Scintillator

Nearly 100% energy transfer at the interface of metal-organic frameworks for X-ray imaging scintillators