One-pot synthesis and self-assembly of colloidal copper(I) sulfide nanocrystals

A simple one-pot method is developed to prepare size- and shape-controlled copper(I) sulfide (Cu(2)S) nanocrystals by thermolysis of a mixed solution of copper acetylacetonate, dodecanethiol and oleylamine at a relatively high temperature. The crystal structure, chemical composition and morphology of the as-obtained products are characterized by powder x-ray diffraction (PXRD), x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The morphology and size of the Cu(2)S nanocrystals can be easily controlled by adjusting the reaction parameters. The Cu(2)S nanocrystals evolve from spherical to disk-like with increasing reaction temperature. The spherical Cu(2)S nanocrystals have a high tendency to self-assemble into close-packed superlattice structures. The shape of the Cu(2)S nanodisks changes from cylinder to hexagonal prism with prolonged reaction time, accompanied by the diameter and thickness increasing. More interestingly, the nanodisks are inclined to self-assemble into face-to-face stacking chains with different lengths and orientations. This one-pot approach may extend to synthesis of other metal sulfide nanocrystals with different shapes and sizes.