Electrochromic performance of hybrid tungsten oxide films with multiwalled-CNT additions

In this study, tungsten oxide films were prepared by sol–gel technique. Various amounts of multiwalled carbon nanotubes (MWCNTs) were added during sol–gel process to obtain hybrid WO3/MWCNT films. The original and hybrid films were characterized by thermogravimetric analysis, X-ray diffraction analysis, and scanning electron microscopy analysis, whereas the electrochromic performance was evaluated by measuring changes in the optical transmittance caused by potentiostatic charge–discharge intercalation. The influence on the structure and properties of tungsten oxide film due to MWCNT addition was also investigated. The results showed that all of the films were amorphous and exhibited porous microstructure. The electrochromic performance of pristine WO3 film was improved by adding MWCNTs that served as a template for the growth of WO3 and resulted in more porous microstructure. The hybrid tungsten oxide films with 0.1 wt.% MWCNT addition exhibited the best electrochromic performance.