Ordered dispersion of ZnO quantum dots in SiO2 matrix and its strong emission properties

ZnO nanoparticles in the form of quantum dots (QDs) have been dispersed in SiO2 matrix using StÖber method to form ZnO QDs-SiO2 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-SiO2 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.

Graphical abstractA strong white emission during optical excitation and a bright blue fluorescence after removing the excitation from an orderly dispersed ZnO quantum dots in SiO2 matrix indicate possible display applications.Figure optionsDownload full-size imageDownload high-quality image (71 K)Download as PowerPoint slideResearch highlights► ZnO quantum dots have been dispersed in SiO2 matrix randomly and in chain-like ordered form depending on the addition of the precursors using StÖber method. ► Randomly and orderly dispersed ZnO QDs-SiO2 nanocomposites respectively show strong red and white emissions. ► The nanocomposite with ordered dispersion shows a strong blue fluorescence for few seconds after removal of the optical excitation source which is promising for display applications.