METALLOORGANIC DEPOSITION OF TUNGSTEN-OXIDE FILMS FROM ALKYLAMMONIUM TUNGSTATE SOLUTIONS

This paper describes a simple and inexpensive metallo-organic deposition (IMOD) process for forming electrochromic tungsten oxide (WO3) films on glass. The thin films of WO3 were made by air firing (500-700-degrees-C) films from xylene/2-propanol solutions of bis-(di-n-octylammonium) tetratungstatel [(n-C8H17)2NH2]2[W4O13]. The process coats glass with undoped films ranging in colour from faint yellow to dark brown, and can be used to make gradients of these colours. The colour is determined by the firing parameters and results from residual carbon and tungsten suboxides in the film due to incomplete firing. Increased firing temperatures or longer firing times removes the carbon and produces films with higher crystallinity. Electrochemical doping with acid (H+) switches the colour gradient films to a uniformly blue colour.