Electrophoretic deposition of latex-based 3D colloidal photonic crystals: A technique for rapid production of high-quality opals

Three-dimensional colloidal crystals have been grown by electrophoretic deposition on ITO glass supports from aqueous-ethanol colloidal solutions of monodisperse submicrometersized negatively charged polystyrene latex spheres. The technique offers the possibility to produce uniform single-crystal colloidal multilayers on the time scale of minutes, which is a drastic acceleration in comparison with the gravity sedimentation technique that needs weeks or even months. SEM and AFM images of colloidal crystals reveal that close-packed 3D fee ordering of the latex spheres extends over large areas. Electrophoretically deposited colloidal crystals show a pronounced photonic stopband in the visible spectral range in the normal incidence transmission spectra with a position depending on the size of latex spheres. The electrophoretic deposition has also been used for the impregnation of 3D colloidal, crystals with luminescent CdTe nanocrystals. The luminescence spectrum of CdTe nanocrystals shows a dip at the wavelengths corresponding to the spectral position of the photonic stopband of the colloidal crystal.