Keywords: CdSe nanocrystals, cadmium selenide, single-step synthesis, reaction temperature, ligand concentration, nanocrystal shape, crystalline structure, optical properties, nanotechnology, morphology
Effect of reaction temperature and ligand concentration on the shape of CdSe nanocrystals
Colloidal CdSe nanocrystals were synthesised in octadecene solvent using oleic acid and trioctylphosphine as ligands for cadmium and selenium precursors respectively. The reaction parameters, including temperature and ligand concentration, were investigated. The morphology, crystalline structure and optical properties of CdSe nanocrystals were studied by transmission electron microscopy, X-ray diffraction, optical absorption and photoluminescence spectra. It was observed that the reaction parameters greatly affect the shape of nanocrystals. Dot-shaped CdSe nanocrystals were synthesised at high reaction temperature and low oleic acid concentration. In contrast, CdSe tetrapods were formed at lower reaction temperature and higher oleic acid concentration. Simultaneously, the ligand concentration results in the changes in core diameter and aspect ratio of tetrapod arms. The formation of CdSe nanocrystals of various shapes is discussed in relation to the nucleation and growth of CdSe nanocrystals in noncoordinating solvent. The obtained results demonstrate the possibility for controlling the shape of CdSe nanocrystals in single-step synthesis.