Preparation And Luminescent Properties Of Quantum Dots(M=Cd,Zn)MSe

In this paper, a series of CdSe, ZnSe, Cd_xZn_1-xSe quantum dots are prepared by thermal decomposition and aqueous phase refluxing. The main contents and results as following:?1? The band structure, and the density of states of CdSe, ZnSe, Cd_xZn_1-x Se quantum dots are obtained using first-principles and calculation software of CASTEP, and the electrical structure also is analyzed.?2? Monochromatic CdSe quantum dots are synthesized by thermal decomposition at280 ? using CdO and selenium powder as the precursor and different chain length of amine as coating agent. By the XRD diffraction analysis, the crystal phase of CdSe indicates CdSe quantum dots are synthesized. The species of functional groups of the coating agents are characterized by near infrared spectroscopy, and the size and morphology of CdSe quantum dots are characterized by TEM patterns. The relults indicate that particles of samples are uniformly distributed and size of particles is from 2.6nm to 3.5nm. The effects of different chain of amine ligands on the properties of CdSe quantum dots are studied by the excitation,emission and absorption spectra. The emission spectrum of samples prepared with different amines as ligands shifts from 546 nm to 570 nm.?3? CdSe quantum dots are synthesized at 100 ? for 1.5h using CdCl₂, SeCl₄ as precursor and 3-MPA as the coating agent by the aqueous phase refluxing. The material composition is characterized by XRD diffraction and Raman spectrum. The size of CdSe quantum dots is characterized by TEM transmission electron microscopy, and size of particles is from 2.7nm to 3.7nm. The excitation, emission and absorption spectra of the CdSe quantum dots are studied under different Cd/Se in precursor.?4? ZnSe quantum dots are synthesized at 100 ? using ZnCl₂, SeCl₄ as precursor and3-MPA as the coating agent by the aqueous phase refluxing. The material composition is confirmed by XRD diffraction and Raman spectrum. The size of ZnSe quantum dots is characterized by TEM transmission electron microscopy, and size of particles is about 2.3nm to 2.5nm. The excitation, emission and absorption spectra of ZnSe quantum dots are affectedby different Zn/Se in precursor, and emission spectrum shifts from 466 nm to 471.4nm.?5? Cd_xZn_1-xSe quantum dots are synthesized at 100 ? using ZnCl₂, CdCl₂ and SeCl₄ as precursor and 3-MPA as the coating agent by the water heating refluxing reaction?Cd/Zn=0.01, 0.03, 0.05, 0.1 and 0.15?. The material composition, morphology and optical properties are characterized by XRD diffraction, Raman spectrum, TEM patterns, the excitation, emission and absorption spectra. The results reveal Cd_xZn_1-x Se quantum dots are pure phase and the size and the spectra of quantum dots vary regularity with the increasing of Cd/Zn in precursor.