Luminescence Properites And Mechanism Of Inorganic Glass Stabilized Fluorescent Silver Quantum Clusters

Silver nanoclusters[Agm]n+ QCs,which is composed of several to several tens of metal atoms,exhibit a discrete electronic state and size-dependent fluorescence as molecules-like property,due to their size is too small to be comparable to the electron Fermi wavelength.By adjusting the size of[Agm]n+ QCs,it exhibits strong fluorescence from visible to near-infrared.Therefore,[Agm]n+ QCs has broad application prospects in the fields of bio-nanotechnology,flexible display,white light illumination,and solar cells.However,since[Agm]n+ QCs are highly susceptible to strong interaction with each other and irreversibly agglomerate to reduce surface energy,it is necessary to stabilize[Agm]n+ QCs with a ligand and uniformly disperse it while retaining the fluorescence activity.Using inorganic glass network structure to stabilize and disperse[Agm]n+ QCs,the obtained silver-doped inorganic luminescent glass has shown broad spectrum and high-efficiency characteristics,and has great application potential in white LED illumination field,but the emission of silver nanoclusters[Agm]n+ QCs is lack of red light components,and the color rendering index is low,which limits its application in white light illumination.At present,the bottleneck of inorganic glass stabilized[Agm]n+ QCs for LED illumination is that the[Agm]n+ QCs luminescence mechanism is still unclear,and no efficient red luminescent center has been developed.For this reason,this paper uses a differential phase strategy to form the blue luminescene center Ag+,green luminescene center[Agm]n+ QCs and red luminescene center[Ag2]2+ in boroaluminosilicate glass by fluorine-rich phase,boron-rich phase,silicon-rich phase,ZnO-Al2O3-rich and SrO-Al2O3-SiO2-rich phases.This paper solved the problem of silver quantum cluster doped inorganic luminescent glass in LED illumination by the formation of high-efficiency red[Ag2]2+ luminescence center.Specifically,this paper mainly carried out the following research:(1)B2O3-Ag2O,B2O3-SiO2-Ag2O,B2O3-Al2O3-Ag2O and B2O3-Na2O-Ag2O glass were successfully prepared by melt quenching method.The effects of the concentration of Ag,glass comosition and glass network structures on the formation of Ag+/[Ag2]2+/[Agm]n+ QCs and their spectroscopy properties were well studied.According to density functional theory(DFT),the configuration,electronic structure and energy state of free state and B2O3 stabled[Agm]n+ QCs have been studied in detail,which figure out the energy level transition of Ag+/[Ag2]2+/[Agm]n+ QCs by energy configuration coordinate(CCD)diagram.The effect of B2O3 on[Agm]n+ QCs luminescence is explained by ligand-metal charge transfer theory(LMCT).(2)Further,a phase separation strategy was proposed to study the glass forming ability,phase separation behavior and crystallization behavior of SiO2-Al2O3-B2O3-SrO/SrF2-ZnO/ZnF2-Na2O-Ag glass system,and by obtaining Ag+/[Agm]n+ QCs enriched B2O3 differential phase,[Agm]n+ QCs enriched SrO-Al2O3-SiO2 and[Ag2]2+enriched ZnO-Al2O3 differential phase,white light emission glass or glass ceramic has been achieved.The enrichment behaviors of different states of Ag,including Ag+,[Ag2]2+,[Agm]n+ QCs and Ag nanoparticles,in different phase regions of glass were investigated by doping concentration,glass composition,phase separation structure and heat treatment regime,as well as the effect on the absorption,excitation and emission spectra.A class of silver quantum cluster doped glass and glass ceramics with high-efficiency,broad-spectrum,low-color temperature and high color rendering index fluorescent emission bands in the visible light band were obtained.This provided a new material basis for high power LED lighting devices based on glass and glass ceramic fluorescent blocks.