Fabrication of solid electrolyte Ta2O5 thin film by reactive dc magnetron sputtering suitable for electrochromic all-solid-state switchable mirror glass

We investigated the fabrication conditions of a solid electrolyte Ta2O5 thin film suitable for an electrochromic (EC) all-solid-state switchable mirror glass to reduce material and processing costs. The film was deposited by reactive dc magnetron sputtering in a mixture gas of argon and oxygen. The electrochemical properties of the film on a WO3/ITO/glass substrate and the optical switching properties of the EC switchable mirror device were investigated, considering the thickness of the Ta2O5 thin film. All the films on WO3/ITO/glass substrates in this work exhibited similar current density, as measured by cyclic voltammetry. The electrochemical properties of the film with thickness reduced by 75% were almost the same as those of the conventional film. However, the device constructed with the thinner film displayed poor optical switching properties. Switching from the reflective state to the transparent state upon application of a voltage, the device with a 100-nm-thick film required a switching time that was 3 times longer than that of the conventional device constructed with a 400-nm-thick film. These results indicate that suitable fabrication conditions for the solid electrolyte Ta2O5 thin film of EC all-solid-state switchable mirror glass can potentially be found that reduce consumption of materials and shorten processing time. (c) 2011 The Ceramic Society of Japan All rights reserved