Synthesis And Characterization Of PbSe_1-xS_x Alloyed Quantum Dots Via Cation Exchange

Compared to binary quantum dots?QDs?, ternary alloyed QDs have so many advantages of electrical and optical properties that ternary alloyed QDs attracted numerous researchers' interest and intensive attentions. Ternary alloyed QDs have the potential application in different areas. But ternary alloyed QDs are different from binary QDs. the difficulty in synthesis is that the reaction rate changes with various reactants in mixed solution. A major challenge for the synthesis of ternary alloyed QDs is to obtain a random distribution of alloyed QDs, which requires controlling the reaction of different precursor's solution, therefore QDs it is very difficult in the synthesis of ternary alloyed.In this dissertation, the basic conception and properties of ternary QDs and the research background and present situation of development were firstly introduced, some of its mechanisms of synthesis were analyzed and discussed, and then the synthesis method of ternary CdSe_1-xS_x and PbSe_1-xS_x alloyed QDs were described in details. Synthesis of precursor CdSe_1-xS_x ternary QDs is basically matured and process is not complicated, which is easy to get a good uniform distribution of QDs. The cation exchange method was employed to synthesize ternary PbSe_1-xS_x alloyed QDs. A series of characterization and analysis were utilized for precursor and the ultimate samples.UV-visible absorption and photoluminescence spectroscopy were used to analyze the dimensional change of ternary alloyed QDs and the relationship between the absorption peak and injection Se/S ratio, respectively. Photoluminescence spectroscopy was used to analyze the stability of alloyed QDs in ambient environment. X-ray fluorescence spectrometry?XRF? was employed to determine the elements composition and ratio. X-ray diffraction?XRD? was utilized to determine the lattice structure of synthesized ternary QDs. The microstructures and distribution of the alloyed QDs were observed, and determined the uniformity of distribution by Field Transmission Electron Microscope?FTEM?.