Synthesis of water-soluble ZnO nanocrystals with strong blue emission via a polyol hydrolysis route

Abstract

ZnO nanocrystals with strong blue emission have been synthesized via a facile polyol hydrolysis route. The as-synthesized ZnO nanocrystals were stable in water, even at basic or acidic aqueous conditions. The water stability of such ZnO nanocrystals was provided by the hydroxyl groups of triethylene glycol (TREG) and also the carboxyl group of oleic acid (OA) on their surfaces. We found that heat temperatures, heat times and concentrations of OA were all important factors that influence the particle size and the crystallinity of the ZnO nanocrystals. Interestingly, the photoluminescence properties of ZnO nanocrystals were not dependent on the particle size, but were attributed to the surface defects on ZnO which were closely related to the process of ZnO nanocrystals coated by TREG. Such ZnO water-disperse nanocrystals with intense blue fluorescence are expected to be of use for further practical applications, such as for the applications in biological fluorescence labelling.