Study On Preparation And Property Of Fe-doped Znse Core-shell Structure Fluorescent Nanoparticles

Semiconductor fluorescence quantum dots,have become one of the research hotpot in the past dozen years due to their superior optical properties.The toxicity of Cd-based QDs limit their further application in the field of biological analysis.Compared with Cadmium-based QDs,Zn-based QD have lower toxicity,which has attracted much attention.Considering the influence of PL QY and stability on its further application,it is of great significance to synthesize Zn-based QDs with high PL QY and good stability.Therefore,a layer of ZnSe or ZnSe/ZnS shell with suitable shell thickness have been overcoated on the surface of ZnSe-doped quantum dots aim to improve the fluorescence quantum yield.Additionally,to further enhances the stability and functionality of the quantum dots,a layer of inert silica is coated on the quantum dots.The results are as follows:1)Water-dispersed ZnSe:Fe/ZnSe core/shell quantum dots have been synthesized successfully using L-cysteine as a stabilizer thought an epitaxial growth method.The influence of shell thickness,Zn/Se raw material ratio,and the different concentrations of NaCl,H₂O₂ and PH buffer solution on the fluorescence properties of the as-obtain quantum dots were investigated systematically.The as-prepared product were characterized by X-ray power diffraction?XRD?,transmission electron microscope?TEM?,infrared spectrum?IR?,UV-Vis absorption spectrum?UV-Vis?and photoluminescence spectrum?PL?.The results show ZnSe:Fe/ZnSe core/shell quantum dots owe to the cubic zinc blende structure,approximate sphere and have good monodispersity.When mol ratio of n?ZnSe:Fe?to n?ZnSe?is 1:0.2,and the ZnSe shell raw material mol ratio of Zn²⁺to n Se^2-is 1:1,the fluorescence quantum yield of as-prepared quantum dots increased from 8.9%to 15.68%.Compared with ZnSe:Fe quantum dots,the stability of ZnSe:Fe/ZnSe core/shell quantum dots enhance obviously.2)Water-dispersed ZnSe:Fe/ZnSe/ZnS core/shell/shell quantum dots have been synthesized successfully using L-cysteine as a stabilizer thought an epitaxial growth method.The influence of shell thickness,Zn/Se ratio,and the different concentrations of NaCl,H₂O₂ and PH buffer on the fluorescence properties of the as-obtain quantum dots were investigated.The resulting product were characterized by XRD,EDX,TEM,IR,UV-Vis and PL.The results show ZnSe:Fe/ZnSe/ZnS core/shell/shell quantum dots are the cubic zinc blende structure,approximate sphere and have good monodispersity.The fluorescence quantum yield of the as-obtain quantum dots increased from 15.68%to 26.19%after ZnS shell formed.Compared with ZnSe:Fe/ZnSe core/shell quantum dots,the stability of ZnSe:Fe/ZnSe/ZnS core/shell/shell quantum dots enhance obviously.3)Water-dispersed ZnSe:Fe/ZnS/SiO₂-NH₂ nanoparticle have been synthesized by Stober method.The influence of reaction pH,reaction temperature,reaction time,amount of quantum dots,amount of TEOS and amount of APTES on the fluorescence properties of ZnSe:Fe/ZnS/SiO₂-NH₂ nanoparticle were investigated systematically.The as-prepared nanoparticle were characterized by XRD,EDX,TEM,IR,UV-Vis,PL and Zata potential.The results showed that ZnSe:Fe/ZnS/SiO₂-NH₂ nanoparticle are spherical,have good monodispersity.Compared with ZnSe:Fe/ZnS quantum dots,the quantum yield increased from 18.9%to 20.45%,the stability of ZnSe:Fe/ZnS/SiO₂-NH₂ nanoparticle enhance obviously.