修饰剂链长变化对核壳结构CdS纳米晶尺寸和光学性质的影响

采用液液两相法,在甲苯和水的两相体系中制备了由不同烷基链长单硫醇修饰的具有无机-有机核壳结构的CdS半导体纳米晶.使用透射电子显微镜(TEM)、X射线粉末衍射(XRD)和紫外-可见吸收光谱(UV-Vis)对样品的结构和组成进行了表征.结果表明,样品CdS半导体纳米晶是由无机纳米核及其表面化学吸附的硫醇组成的,而且壳层有机修饰剂对无机纳米核的尺寸和光学性质影响很大.进一步分析发现,层修饰剂的烷基链长和CdS纳米核的尺寸之间存在着类似抛物线的关系.这主要是由于在两相体系中,Cd纳米核的形成和成长两个阶段受到修饰剂在有机相中的迁移率以及其在纳米核表面的组装有序度两种关键因素竞争结果的控制.

Effect of Difference of Modifiers' Chain on Size and Optical Property of Core-shell CdS Nanocrystals

Core-shell CdS nanocrystals, which were modified by different-chain length alkyl thiols, were chemically synthesized by a new liquid-liquid two-phase method. The structure and composition were investigated with UV-Vis absorption spectra, X-ray diffraction, and transmission electron microscopy. The results showed these as-prepared samples consisting of a nano-CdS core and a capped-layer of thiols chemically absorbed on the surface, and the modifiers had a great effect on the size and optical property of the inorganic nano-core. According to further analysis, it was found that the size of CdS nano-core had a quasi-parabola relation with the chain length of the modifiers, which was caused by the competitive result of the surface mobility and self-assembly order of the modifiers in the course of nucleation and growth of CdS nano-core