Facile and Rapid Fabrication of Opal Photonic Crystals by Electrophoretic Deposition

The use of photonic crystals (PCs) is gaining interest regarding the interaction between light and organized structures. However, there are limitations to their use, such as production cost, rate, and substrate size. This study demonstrates an efficient and cost-effective fabrication of an opal structure based on the electrophoretic deposition (EPD) of self-made silica particles. The process allows one to reduce the fabrication time compared to classical evaporation or sedimentation methods, which can take days (evaporation) or weeks to months (sedimentation), while this method takes only 2 min. Silica particles with a diameter of less than 300 nm exhibit a markedly low sedimentation rate. Nevertheless, when they form a close-packed structure, they display a partial band gap in the visible region. The resulting opals are iridescent, from blue to red, and display additional angle-dependent colors. Furthermore, the synthesis of silica particles was completed within a 2 h time frame. Their washing, including a centrifugation step, did not result in the formation of aggregates. Such particles tend to break the long-range order in the PCs.