Fabrication of Large-Area Colloidal Crystals by Electrophoretic Deposition in Vertical Arrangement

Fabrication of large-area colloidal crystals (400 mu m(2)) with superb uniformity in multiple layers (similar to 128 layers) from SiO2 microspheres (similar to 400 nm) was achieved by electrophoresis in vertical arrangement. With a large difference in electrode areas and selection of ethanol as the solvent, we investigated self-assembly with SiO2 suspensions at various pH and electric fields of 20-100 V cm(-1). Colloid formations with negligible vacancies and small-angle grain boundaries were obtained at a suspension of pH approximate to 10 and electric field of 20 V cm(-1). Our fabrication scheme enables construction of colloidal crystals with significantly reduced structural disorders as compared to conventional routes. (C) 2008 The Electrochemical Society.