Ordered dispersion of ZnO quantum dots in SiO_2 matrix and its strong emission properties

摘要

ZnO nanoparticles in the form of quantum dots (QDs) have been dispersed in SiO_2 matrix using St?ber method to form ZnO QDs-SiO_2 nanocomposites. Addition of tetraethyl orthosilicate (TEOS) to an ethanolic solution of ZnO nanoparticles produces random dispersion. On the other hand, addition of ZnO nanoparticles to an already hydrolyzed ethanolic TEOS solution results in a chain-like ordered dispersion. The photoluminescence spectra of the as-grown nanocomposites show strong emission in the ultraviolet region. When annealed at higher temperature, depending on the sample type, these show strong red or white emission. Interestingly, when the excitation is removed, the orderly dispersed ZnO QDs-SiO_2 composite shows a very bright blue fluorescence visible by naked eyes for few seconds indicating their promise for display applications. The emission property has been explained in the light of structure-property relationship.