Spontaneous Self-Assembly of Thiol-Capped CdTe Nanoparticles Into Nanowires Under Dark Conditions

Thiol-capped cadmium telluride (CdTe) nanoparticles (NPs) self-assembled into nanowires (NWs) under dark conditions, and the evolutionary process was investigated. Thiolglycolic acid (TGA) was selected as one of the stabilizers and a TGA-to-Cd ion ratio of 1.3 rather than the traditional 2.4 ratio was used. The reduced amount of the stabilizer and the oxidation of tellurium ions on CdTe NP surface under dark conditions resulted in reorganization from individual NPs into NWs consisting of multi-layers of individual NPs. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were performed to characterize the synthesized nanostructures. The NWs produced were straight and long, with lengths ranging from 500 nm to 10 μm. Photoluminescence (PL) showed that the nanostructure wavelengths were slightly blue-shifted from 546 to 539 nm. Both control of the amount of stabilizer and oxidation of Te ions acted as driving forces to form NWs. Thus, small modifications in synthesis yielded a major difference in the final nanomaterial structure. The suggested synthetic procedure provides a viable pathway for the fabrication of nanomaterials.