Thermally Activated Delayed Fluorescence Coinage Metal Cluster Scintillator

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.