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.