High Quality ZnSe and ZnS Nanocrystals Formed by Activating Zinc Carboxylate Precursors

Nearly monodisperse ZnSe and ZnS nanocrystals were formed in noncoordinating solvents using alternative precursors. The parameter window for the growth of high quality zinc chalcogenide nanocrystals was found to be much narrower than that of the corresponding cadmium chalcogenide nanocrystals. In contrast to syntheses performed in coordinating solvents, generic oxygen containing ligands, such as fatty acids, were found to be reasonable ligands for the formation of ZnSe and ZnS nanocrystals. Activation of the zinc precursor (zinc fatty acid salts) by alkylamines was found to be critical for the formation of high quality ZnSe nanocrystals. The photoluminescence (PL) quantum yield (QY) of ZnSe nanocrystals reached as high as 50% with a full width of half-maximum (fwhm) as narrow as 14 nm. The band gap PL of ZnS nanocrystals was always mixed with a deep-trap tail. The PL fwhm of the band gap emission of the ZnS nanocrystals was typically between 10 and 12 nm.