Preparation And Photophysical Properties Of Cadmium Telluride Quantum Dot Films

The particle size of the CdTe quantum dot material is about several nanometers,and has unique physical characteristics and optical linearity compared with the CdTe bulk material.Because the stability of the quantum dot itself is good and the monodispersity of the particle is relatively good,the emission wavelength can be adjusted to be applied to bio fluorescent tags,solar cells,temperature sensors,laser protection and other fields.Quantum dot film materials are made of quantum dots and polymer polymerization have higher stability,and provide more possibilities for studying the physical properties of quantum dots.Therefore,it is very important to study the physical properties and optical properties of quantum dots and their thin films.First,this paper performed material preparation and characterization.In the process of preparing CdTe quantum dots,four different sizes of CdTe quantum were synthesized by using fresh sodium hydride solution as a reactant and thioglycolic acid as a stabilizer,by changing the pH and reaction time of the solution.The CdTe/PVA composite films were prepared by injecting CdTe solutions with four different sizes of QDs into polyvinyl alcohol(PVA).The above samples were characterized by UV-visible and fluorescence spectra.The influencing factors of the experimental results are analyzed and the physical mechanism was given.And then,in this paper,low-temperature fluorescence spectroscopy experiments were performed on four kinds of films.The temperature was reduced with liquid nitrogen,and the temperature control instrument was used to control the temperature.The step length was 20 K and the variation range was 80~300 K.Through theoretical analysis and numerical fitting,the peak intensity,peak wavelength,and the variation of the spectral full width at half maximum with temperature were analyzed,and the quantum size effect,the energy activation transition of heat activation defects,and the coupling of exciton phonons in the temperature change process were obtained.The last,In this paper,under the experimental conditions of output pulse of 130 fs and output wavelength of 800 nm,nonlinear optical experiments were performed on different sizes of CdTe quantum dot solutions and films.The nonlinear absorption transmittance curves were studied to study the nonlinear optical properties of the material.The effect of quantum dot size on the nonlinear absorption coefficient was studied,and the nonlinear absorption characteristics of the solution and the thin film were compared to provide a theoretical basis for studying the photophysical properties of the material.