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 dep osition on ITO glass supports from aqueous-ethanol colloidal solutions of m onodisperse submicrometersized negatively charged polystyrene latex spheres . The technique offers the possibility to produce uniform single-crystal co lloidal multilayers on the time scale of minutes, which is a drastic accele ration in comparison with the gravity sedimentation technique that needs we eks or even months. SEM and AFM images of colloidal crystals reveal that cl ose-packed 3D fee ordering of the latex spheres extends over large areas. E lectrophoretically 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 electr ophoretic deposition has also been used for the impregnation of 3D colloida l, crystals with luminescent CdTe nanocrystals. The luminescence spectrum o f CdTe nanocrystals shows a dip at the wavelengths corresponding to the spe ctral position of the photonic stopband of the colloidal crystal.