Preparation And Application Of Scintillator Of Cs₃Cu₂X₅ Nanocrystals

In recent years,metal halide perovskite nanocrystals(NCs)have a low-cost solution process,high fluorescence quantum yield(PLQY)(?100%),narrow emission line-widths(12?42 nm),and wide color gamut(?140%NTSC)and other advantages,and is widely used in the field of optoelectronic devices,such as lighting-emitting diodes(LED),solar cells(PV)and photodetectors.Recently,all-inorganic perovskites NCs as scintillators have shown great application potential in the field of X-ray detection and imaging.However,the presence of toxic element lead hinders the commercial development of perovskite NCs photovoltaic devices.Second,due to the small Stokes Shift of lead-halogen perovskite NCs,there is a serious Self-absorption effect,which will greatly reduce the optical coupling output efficiency of NCs thin films,further limiting its potential application in the field of scintillators.Therefore,it has become a research hotspot and difficulty to develop non-toxic,large Stokes Shift and high fluorescence quantum yield all-inorganic metal halide NCs in this field.In this paper,zero-dimensional all-inorganic copper-based halides Cs₃Cu₂X₅NCs(X=Cl,Br,I)were prepared by using non-toxic element monovalent copper and introducing the In X₃ precursor to inhibit the nucleation growth process of nanocrystal.The growth mechanism and luminescence mechanism of Cs₃Cu₂X₅ NCs were systematically studied.Finally,Cs₃Cu₂I₅ NCs were prepared scintillator films,and their scintillation properties and X-ray imaging were studied.The main research results of this work are as followed:(1).Specifically,Cu X and In X₃ are used as precursors,and cesium oleate is used as a cesium source.By adjusting the injection temperature,growth temperature,and the ration of the amount of Cu and In,the emission wavelength of Cs₃Cu₂X₅ NCs is adjustable between 445?520 nm.What's more,the fluorescence quantum yield of blue light Cs₃Cu₂I₅ NCs is 73.7%.(2).By characterizing the photophysical properties of Cs₃Cu₂X₅ NCs,we can conclude that Cs₃Cu₂X₅NCs are self-trapped exciton luminescence,this is mainly due to the zero-dimensional crystal structure of Cs₃Cu₂X₅NCs,which leads to a strong quantum confinement effect of this material.The photogenerated electron-hole pairs are strongly confined in the isolated[Cu X₅]^3-structure,which isn't easy to separate,so there is a high chance of radiation recombination,with a high fluorescence quantum yield.(3).Based on the excellent advantages of Cs₃Cu₂I₅ NCs,we have prepared Cs₃Cu₂I₅ NCs scintillator films,and characterized the performance and X-ray imaging application of Cs₃Cu₂X₅ NCs scintillator.Its light output is about 3.8 times of lead halide perovskite NCs,It is used for X-ray imaging and exhibits a high imaging resolution with a resolution of up to 0.32 mm.