Optimize Synthesis Of Compound Semiconductor Nanomaterials In The Mild System

Semiconductor nanoparticles, also known as quantum dots (QDs), is a kind of range of bulk materials and single molecules of the nanocrystals. Due to its small size effect, surface-interface effect, quantum size effects, etc, nanocrystal has demonstrated excellent performance in the light, electricity, magnetism, heat and other aspects, making nano-semiconductor material in optoelectronics, catalysis, sensing, biological, and other areas have shown a potential broad application prospects.â…¡-â…¥type semiconductor nanomaterials, especially CdS, CdSe these two important quantum dots, both in the application or in the synthesis of research have aroused widespread concern.Based on the predecessors, this dissertation has studied synthesis of CdS, CdSe quantum dots and the core-shell CdSe/CdS quantum dots in the two-phase system:(1) In a mild and control easily condition, a solution of CdOA and oleic acid (OA) in toluene and a solution of thiourea in water, by controlling the reaction time, can synthesize different sizes of CdS nanocrystals at the liquid-liquid interface; (2) At room temperature or in the autoclave, a solution of CdOA and oleic acid (OA) in cyclohexane, NaHSe as a selenium precursor composition of water-soluble in water phase, CdSe quantum dots can be generated in the two-phase interface. By optimizing the ratio of reactants, reaction temperature, reaction time, the amount of monomer Se, quantum dots can be controlled particle size, surface defects, finally we has obstained different colors of CdSe quantum dots solution; (3) A solution of CdOA and oleic acid (OA) in cyclohexane, NaHSe as a selenium precursor composition of water-soluble in water phase, CdSe quantum dots can be generated first, then adding oleic acid and thiourea aqueous solution into the original solution, finally we can coated successfully outside the CdSe shell with a layer of CdS. By altering conditions of the amount of monomer Se, thiourea monomer amount, reaction temperature, reaction time of cladding, we can synthesized a series of different particle size of CdSe/CdS core-shell quantum dots. Besides compared to the nuclear quantum dots, the optimization of synthesized core-shell quantum dots'fluorescence were improved a lot. X-ray powder diffraction (XRD), transmission electron microscopy (TEM) technique, Fluorescence Spectrometer and UV-spectrophotometer were used to analyze the as-synthesized QDs' crystal. As a result, the sythesized QDs with narrow size distribution were cubic structure and have good optical property.This experiment's advantages are operated simply, mild conditions, inexpensive reagents, non-toxic harmless, suitable for promotion. Quantum dots can be used as fluorescent modification in protein, DNA, RNA and other biological macromolecules, thus to achieve molecular diagnostic testing, analysis is of great significance.