All sol-gel electrochromic system for plate glass

Abstract

The development on an all sol-gel electrochromic system for large area devices is described. Previously developed syntheses routes for tungsten oxide, WO3, coating sols and cerium oxide-titanium oxide sols, CeO2-TiO2, were employed, which enabled large substrates (35 X 35 cm2) to be coated homogeneously and without visible cracking. Optoelectrochemical measurements were employed to determine the variation of the electrochromic properties (change in optical density, ΔOD, and switching times) of WO3 layers, investigated as a function of coating parameters, such as chamber humidity and the temperature of heat treatment. A novel composite electrolyte system, based on organically modified silanes, was developed, which has an ionic conductivity of 10-5 S cm-1 at 25°C. Cells were constructed in two formats: 10 X 15 cm2 and 35 X 35 cm2. Switching times less than one minute were achieved for the smaller format with a change in transmission from 75% to 20% (at λ = 0.633 µm).