Blue-emitting small silica particles incorporating ZnSe-based nanocrystals prepared by reverse micelle method.

ZnSe-based nanocrystals (ca. 4-5 nm in diameter) emitting in blue region (ca. 445 nm) were incorporated in spherical small silica particles (20-40 nm in diameter) by a reverse micelle method. During the preparation, alkaline solution was used to deposit the hydrolyzed alkoxide on the surface of nanocrystals. It was crucially important for this solution to include Zn(2+) ions and surfactant molecules (thioglycolic acid) to preserve the spectral properties of the final silica particles. This is because these substances in the solution prevent the surface of nanocrystals from deterioration by dissolution during processing. The resultant silica particles have an emission efficiency of 16% with maintaining the photoluminescent spectral width and peak wavelength of the initial colloidal solution.