Electrochromic properties of MoO3-WO3 thin films prepared by a sol-gel method, in the presence of a triblock copolymer template

Hybrid MoO3-WO3 thin films were deposited on conductive indium tin oxide (ITO) glass substrates by a sol-gel dip-coating technique. The influence of the annealing temperature (200–500°C), concentration of MoO3 (0–10%), and Pluronic P123 triblock copolymer (0–20% w/v) used as a template, were investigated. It was found that the 5% MoO3-95% WO3 films prepared without template and annealed at 200°C, exhibited the highest coloration efficiency, the best cycling stability and shortest response time, an overall improvement with respect to a WO3 film. It is thought that the surface roughness and the low crystallinity of the films contribute to their improved electrochromic properties. In addition, porous MoO3-WO3 films with well-connected micro-pores, prepared with 2% w/v Pluronic P123 and annealed at 300°C, showed significantly improved electrochromic performance.