【摘要】 采用低温水热技术,分别以柠檬酸、聚乙二醇(PEG400)和甲硫氨酸为稳定剂,在水相中合成了核壳型CdSe/CdS量子点,研究了稳定剂、CdSe与CdS物质的量比对量子点发光性能和结构的影响。XRD结果表明,当CdSe∶CdS在1∶3~4时,CdS主要在CdSe的外延生长,形成核壳型纳米粒子,当比例达到1∶5时,CdS单独成晶现象严重。CdSe∶CdS=1∶4时,核壳型量子点具有较高的荧光发射效率。TEM研究表明CdS在CdSe外表面生长形成较为完整的壳层,有效钝化CdSe表面,减少表面缺陷,从而显著提高CdSe量子点的发光效率。CdSe核尺寸为2~3nm的核壳型纳米粒子外包裹一层SiO2壳后,荧光发射效率没有显著提高,发射峰位置无明显红移。量子点包壳后能有效提高该量子点的光化学稳定性,提高量子点的生物相容性。更多还原

【Abstract】 Core-Shell CdSe/CdS semiconductor quantum dots at different molar ratio for CdSe vs CdS were synthesized in aqueous solution at room temperature using citric acid as stabilizer followed by encapsulation of CdSe/CdS quantum dots in SiO2.The prepared CdSe/CdS QDs and water-soluble SiO2 coated CdSe/CdS were characterized by IR spectra,fluorescent emission spectra,X-ray powder diffraction and eclectronic transmission microscopy(TEM).The results showed that core-shell CdSe/CdS nanorods obtained the best fluorescence quantum yields at molar ratio of 1∶4 and CdSe core were about 2 nm in diameter.The fluorescence properties of the CdSe/CdS quantum dots were sensitive to the stabilizer used in reaction.The surface of CdSe quantum dots was passivated by CdS,which resulted in the effective reduction of the surface traps and the enhancement in PL intensity.Encapsulation of CdSe/CdS quantum dots in SiO2 provided CdSe/CdS nanocrystal with good stability and biocompatibility.更多还原