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 Tb3+ and Eu3+ 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−1, 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.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/advs.202207004

High‐Performance X‐Ray Imaging using Lanthanide Metal–Organic Frameworks

Scintillators with high X-ray imaging performance are highly desired. The traditional inorganic scintillators are restricted by the rigorous preparation conditions and easy deliquescence. While the organic scintillators are suffered from...

Rational design and synthesis of scintillating lanthanide coordination polymers for high efficient X-ray imaging

Smart control of ionic interactions is a key factor to manipulate the luminescence dynamics of lanthanides and tune their emission colors. However, it remains challenging to gain a deep insight into the physics involving the interactions between heavily doped lanthanide ions and in particular between the lanthanide sublattices for luminescent materials. Here we report a conceptual model to selectively manipulate the spatial interactions between erbium and ytterbium sublattices by designing a multilayer core-shell nanostructure. The interfacial cross-relaxation is found to be a leading process to quench the green emission of Er3+, and red-to-green color-switchable upconversion is realized by fine manipulation of the interfacial energy transfer on the nanoscale. Moreover, the temporal control of up-transition dynamics can also lead to an observation of green emission due to its fast rise time. Our results demonstrate a new strategy to achieve orthogonal upconversion, showing great promise in frontier photonic applications.

Selectively Manipulating Interactions between Lanthanide Sublattices in Nanostructure toward Orthogonal Upconversion.

Materials with tunable emission colors has attracted increasing interest in both fundamental research and applications. As a key member of light-emitting materials family, lanthanide doped upconversion nanoparticles (UCNPs) have been intensively demonstrated to emit light in any color upon near-infrared excitation. However, realizing the trichromatic emission in UCNPs with a fixed composition remains a great challenge. Here, without excitation pulsed modulation and three different near-infrared pumping, we report an experimental design to fine-control emission in the full color gamut from core-shell-structured UCNPs by manipulating the energy migration through dual-channel pump scheme. We also demonstrate their potential application in full-color display. These findings may benefit the future development of convenient and versatile optical methos for multicolor tuning and open up the possibility ofconstructing full-color volumetric display systems with high spatiotemporal resolution.

Xintong Zhang

Papers

High‐Performance X‐Ray Imaging using Lanthanide Metal–Organic Frameworks

Orthogonal Trichromatic Upconversion with High Color Purity in Core-Shell Nanoparticles for a Full-Color Display.