Preparation And Optical Properties Of Doped ZnSe Quantum Dots

In recent years,quantum dots(QDs)have attracted great interest from many scholars at home and abroad due to the special physicochemical properties.In this paper,we prepare the doped ZnSe QDs,whicn can extend the fluorescence wavelength range to 700 nm and study the optical properties of quantum dots.And then as-synthesized QDs were prepared QDs films.The optical properties and surface morphology of QDs films are investigate.The specific conte nt of this dissertation is as follows:(1)In this thesis,ZnSe:Cu QDs with excellent fluorescence and non-toxic were prepared after the copper impurities were doped into ZnSe QDs by the cationic-reversed-injection method in aqueous solution and growth-doping method,using thioglycolic acid(TGA)as a surfactant.The effects of p H value,reaction temperature and reactant molar ratio on the microstructure and optical properties of ZnSe:Cu QDs were investigated.The experimental results indicate that when the p H value of the reaction solution was 9 and the reaction temperature was 90�C,the molar ratio of the reactant was n _Zn²⁺:n _Cu²⁺=1:0.1 and the reaction time was 2 h,the as-synthesized ZnSe:Cu QDs have strong band edge emissions between the conduction band and the valence band.ZnSe:Cu QDs with the average particle size of 3.0�0.2 nm show approximately spherical and belong to the zinc blende structure.The central luminescence wavelength and full width at half maximum(FWHM)of ZnSe:Cu QDs is approximately 503 nm,and 90 nm,respectively.In addition,the fluorescence quantum yield(QY)and average fluorescence lifetime of ZnSe:Cu QDs is about 20%and 113.8 ns,respectively.(2)ZnSe:Cu,In QDs was synthesized after the copper and indium impurities were doped into ZnSe QDs by growth-doping method in aqueous solution.The effects of p H value,reaction temperature and reactant molar ratio on the microstructure and optical properties of ZnSe:Cu,In QDs were investigated.The experimental results show that ZnSe:Cu,In QDs with excellent performance was successfully prepared when the p H value of the reaction solution was 7.5,the reaction temperature was 90�C,the molar ratio of the reactants was n _Zn²⁺:n _Cu²⁺:n _In³⁺=1:0.1:0.3,and the reaction time was 2 h.ZnSe:Cu,In QDs with with the average particle size of 4.29�0.2 nm show approximately spherical.The central emission wavelength and FWHM of ZnSe:Cu,In QDs is approximately 622 nm and 110 nm,respectively.In addition,the fluorescence QY and average flurescence lifetime of ZnSe:Cu,In QDs is around 12.4%and 139.05 ns,respectively.(3)In this paper,a photolithography technology was employed to prepare a square bank on a glass substrate.As-synthesized QDs were filled into the square bank by spin-coating and titration method and a quantum dots films were successfully prepared.The effects of the concentration of QDs ink,the thickness and the annealing time on the uniformity and optical properties of QDs film were discussed.The experimental results show that the ZnSe:Cu and ZnSe:Cu,In QDs films have excellent film qualities and optical properties,which are prepared at an ink concentration ratio of 1:3 and 1:2,respectively,the film thickness of 6.9?m,and the annealing time of 20 min.The transmittance of ZnSe:Cu QDs film was above 60%,the fluorescence lifetime was around 47.64 ns,and the color coordinate was(0.2183,0.4352).The transmittance of ZnSe:Cu,In QDs film was above 55%,the fluorescence lifetimewas 66.25 ns,and the color coordinates are(0.5569,0.384).ZnSe:Cu and ZnSe:Cu,In QDs films can convert green light and red light by an ultraviolet LED.which can provide the theoretical basis in combining quantum dots with UV LEDs to achieve color conversion of LEDs and provides an alternative method for display applications.