電解析出法によるエレクトロクロミックなV₂O₅薄膜の生成

抄録

A uniform and adherent deposit of V₂O₅ thin film onto electroconductive glasses (ITO) has been obtained by electrolyzing colloidal V₂O₅ solution.
A V₂O₅ sol was prepared from dilute solution of ammonium metavandate by passing the solution through an ion-exchange column (filled with Dowex 50 WX2 resin). The sol was then allowed to stand in a 40°C thermostat for 80 hrs. The viscosity of this sol increased with time, The measurement of the zeta potential of this sol indicated that the sol was negatively charged. Cathodic deposition of V₂O₅ is not a simple electrophoretic nature, since actually the V₂O₅ deposition occurred at the negative pole. We propose a following mechanism; the reduction of polyvanadic acid sol yielded a kind of vanadium bronze which coagulated onto the cathode (ITO) to form a solid film.
On cathodic reduction the color of V₂O₅ film changes to green and on anodic oxidation it changes to light orange. The intermediate color tone has been also obtainable, therefore this system can be used as a multicolor device. The reversibility and durability for the electrochromic uses was almost comparable to a vacuum evaporated film.