Parallel-Plate Conductive Electrodes for the Fabrication of Larger 2D Colloidal Photonic Crystals

Abstract

A new dielectrophoretic force-induced parallel-plate assembly technique was used to achieve close-packed 2D large colloidal photonic crystals on gold electrodes (∼200 nm thick). The electrodes were patterned on a glass substrate using a conventional UV lithography technique. The experimental tests conducted with 5.3 μm carboxyl functionalized polystyrene particles at various ac and dc voltages, frequencies, and particle concentrations showed that larger size (0.25×3 mm2) colloidal photonic crystals were fabricated on the ground electrode rather than on the working electrode. To date, this is the largest colloidal photonic crystal fabricated using this method. The reason behind this phenomenon can be attributed to the electro-osmotic flow in the colloidal system and dipole-dipole attractions between the colloidal particles.