Anodically formed transparent mesoporous TiO2 electrodes for high electrochromic contrast

In the present work, we show that metallic Ti thin films on FTO glass can be completely anodized to a mesoporous oxide layer using a glycerol-K2HPO4 electrolyte at elevated temperatures (similar to 180 degrees C). This results in highly transparent mesoporous oxide coated electrodes that provide a significantly enhanced transparency compared with the classic nanoparticle layers or TiO2 nanotube layers. We show that in electrochromic switching experiments these electrodes therefore exhibit a significantly higher contrast compared to other TiO2 nanostructures. Moreover, this type of anodic titania layer is produced in a fluoride-free electrolyte and adheres very well to the FTO glass, both features that are highly beneficial in view of an application in electrochromic devices.