Thermally Activated Delayed Fluorescence Coinage Metal Cluster Scintillator

Coinage metal clusters are a promisingclass of X-ray scintillatorsto substitute for traditional commercial ones in X-ray imaging dueto their comprehensive advantage. X-ray scintillatorsare widely used in medical imaging, industrialflaw detection, security inspection, and space exploration. However,traditional commercial scintillators are usually associated with ahigh 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 friendlyand highly stable to water and oxygen. The TADF property of 1 endows it with an ultrahigh exciton utilization rate. Combinedwith the effective absorption of X-ray caused by the heavy-atom effectand a limited nonradiative transition caused by close packing in thecrystal state, 1 exhibits an excellent radioluminescenceproperty. Moreover, 1 has good processability for fabricatinga large, flexible thin-film device (10 cm x 10 cm) for high-resolutionX-ray imaging, which can reach 40 & mu;m (12.5 LP mm(-1)). The properties mentioned earlier make the coinage metal clusterpromising for use as a substitute for traditional commercial scintillators.