Thermally Activated Delayed Fluorescence Coinage Metal Cluster Scintillator

Abstract

X-ray scintillators are widely used in medical imaging, industrial flaw detection, security inspection, and space exploration. However, traditional commercial scintillators are usually associated with a high use cost because of their substantial toxicity and easy deliquescence. In this work, an atomically precise Au−Cu cluster scintillator (1) with a thermally activated delayed fluorescence (TADF) property was facilely synthesized, which is environmentally friendly and highly stable to water and oxygen. The TADF property of 1 endows it with an ultrahigh exciton utilization rate. Combined with the effective absorption of X-ray caused by the heavy-atom effect and a limited nonradiative transition caused by close packing in the crystal state, 1 exhibits an excellent radioluminescence property. Moreover, 1 has good processability for fabricating a large, flexible thin-film device (10 cm × 10 cm) for high-resolution X-ray imaging, which can reach 40 μm (12.5 LP mm −1 ). The properties mentioned earlier make the coinage metal cluster promising for use as a substitute for traditional commercial scintillators.

Highly Efficient Stable Luminescent Radical-Based X-ray Scintillator

“…X-ray scintillators have widespread applications in medical imaging, X-ray nondestructive inspection, electron microscopy, and high-energy particle detectors. − The development of X-ray scintillators with high X-ray excited luminescence (XEL) efficiency has attracted widespread attention. − For classic closed-shell X-ray scintillators whose electrons are in pairs, the radioluminescence originated from the radiative transition of excitons from the singlet/triplet state to the ground state (Figure A). However, suffering from spin-forbidden transition, the triplet exciton utilization rate is usually limited. , Thus, the major challenge for the development of high-performance X-ray scintillators was to find an effective strategy to increase the triplet exciton utilization rate. , In recent years, phosphorescent scintillators and thermally activated delayed fluorescence (TADF) scintillators have been reported in succession, which significantly increased the triplet exciton utilization rate and pointed a new direction for the development of high-performance X-ray scintillators. − Nevertheless, the molecular design and material synthesis of these new X-ray scintillators are still a challenge, and it is of great significance to find a universal strategy to design high-performance X-ray scintillators with a high exciton utilization rate.…”

Hybrid Thermally Activated Nanocluster Fluorophores for X-ray Scintillators

“…X-ray scintillation plays an indispensable role in medical diagnosis, industrial inspection, and security, given its ability to convert high-energy ionizing radiation into readily detectable low-energy visible photons. − New scintillators with enhanced abilities for converting X-rays to visible light are actively being explored to improve radioluminescence (RL) intensity and imaging quality. − One promising avenue of investigation is the use of thermally activated delayed fluorescence (TADF) materials, − particularly the hybrid organic–inorganic TADF-like Cu­(I) complexes. Theoretically, these TADF-like Cu­(I) complexes can achieve up to 100% internal quantum efficiency through the reverse intersystem crossing (RISC) process.…”

Coinage Metal Cluster Scintillator for X-ray Imaging

“…Given the extensive applications of X-ray imaging technology, ranging from security checks to medical diagnostics, the design and construction of versatile X-ray imaging scintillators have received widespread attention. In this issue of ACS Central Science , Kai Li, Shuang-Quan Zang, and co-workers report a coinage metal cluster scintillator with thermally activated delayed fluorescence (TADF) activity for high-performance X-ray imaging . TADF emitters produce light by harvesting both singlet and triplet excitons and show great promise in the application of photonics.…”

“…In their recent work published in ACS Central Science , the authors synthesized a gold–copper (Au–Cu) cluster using a simple and mild one-pot method (Figure a). With the introduction of heavy atoms, the Au–Cu cluster exhibited excellent X-ray absorption and emitted bright radioluminescence under X-ray excitation, with a minimum detection limit of 31.7 nGy s –1 (Figure b), lower than that of CsPbBr 3 scintillators (∼50 nGy s –1 ).…”

“…(e) X-ray image of a computer mouse as produced using the large-scale scintillator flexible device. Reproduced with permission from ref . Copyright 2022 American Chemical Society.…”