Electrochromic properties of the V,05 thin films prepared from a spinnable organic vanadium solution were investigated. The films heat-treated at 400 "C showed clear two-step electrochromism, deep blue F? greens yellow, with its response time for obtaining AOD = 0.5 being -2 s. The yellow and green colors showed good memory effects for more than 20 h, while the blue one was considerably degraded within 10 h.

Electrochromic properties of V2O5-TiO2 thin films prepared by a spin-coating method were strongly dependent on the film compositions and heat-treatment temperatures. It was found that the nearly amorphous film of V2O5-TiO2 (3:7 in molar ratio) heat-treated at 400 °C showed coloration to reddish brown when polarized at −0.8 V vs SCE. This new coloration was concluded to be ascribable to amorphous vanadium oxide.

A new wet process was developed for preparing a V2O5 thin film for use in an electrochromic display device. V2O5 powder was dissolved into a mixed solution of benzyl alcohol and iso-butanol to obtain a vanadium solution, which was then spin-coated on an ITO glass followed by a heat treatment at temperatures above 300°C, preferably at 400°C. The resulting crystalline V2O5 thin film was excellent in reversibility of the electrochromism.

The composite thin films of Au-V2O5 were prepared by means of an alternating thermal deposition technique. The electrochromic properties of the films were dependent on Au contents and calcination temperature. The composite film containing 26 at. % Au calcined at 400 °C gave clear electrochromism of reddish-violet (cathodic polarization) ↔ green (anodic). The film had a strong optical absorption peak ascribable to the dispersed Au particles at 615 nm (cathodic) or 555 nm (anodic). The shift of this absorption peak, coupled with that of the absorption edge of the V2O5 matrix, was responsible for the new electrochromism.

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