Designing and fabrication of electrochromic windows using tungsten oxide films prepared through sol-gel coating on a glass

Abstract

In this study, a sol-gel peroxotungstic acid sol was employed to deposit tungsten oxide (WO3) films by the spin-coating technique. In view of smart window applications, electrochromic windows were then designed and fabricated using a thin tungsten oxide film. For this purpose, Glass/ FTO/ WO3/ electrolyte/ FTO/Glass could be of use due to its special structure that consists of an electrochromic layer (WO3) on a transparent conductor (FTO), an electrolyte containing Li+ cations, and a transparent conductor layer. A voltage was applied on the fabricated sample, which was later assesed for its transmission, switching speed, and coloration efficiency. An increase in the coloration efficiency from 87 cm2/C-1 to 99.1 cm2/C-1 was found associated with an increase in the deposition speed. Moreover, the increase in the deposition speed led to a decrease in the coloration and bleaching time duration from 11.4 s to 6.2 s and from 12.8 s to 5.2 s respectively. The results obtained on the thin film WO3 can be useful for electrochromic applications.