Flexible WO3 based electrochromic displays using proton conducting solid electrolytes

Abstract

All solid-state flexible electrochromic displays were fabricated based on WO3 films deposited below 50 °C by heating a hot wire in a rough vacuum of the order of 1 Torr. Indium Tin Oxide (ITO) covered polyethylene tetraphthalate (PET) substrates and gel-like organic electrolytes were used. These proton conductive electrolytes were based on poly(methyl methacrylate) (PMMA) into which a strong Brönsted phosphododecatungstic acid (H 3FW12O40-POM) was added at various concentrations. Tnnsrrdttance measurements were recorded and it was found that all displays exhibited an intense, reversible electrochromic effect. The coloring voltage was found to depend strongly on the content in solids of the electrolyte, the POM's concentration and the basicity of the polymeric matrix. For devices polarized by voltage pulses it was found that the response time was of the order of 500 ms; coloration and bleaching times were comparable. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA,.