Photoelectrochromic devices based on sputtered WO3 and TiO2 films

- Sputtered TiO2 and WO3 are applied for PEC devices with a light induced switching from 61 down to 15%.
- Annealing of TiO2 improves the dye adsorption.
- Electrochromic device, dye sensitized solar cells and photoelectrochromic devices are compared applying the same coating.
- Different layer configurations are compared with the variation of the WO3 and TiO2 layers.

The photoelectrochromic (PEC) device, a combination of a dye solar cell and an electrochromic film, can be used for the dynamic solar control of buildings under illumination or with an external voltage. Typically, titanium oxide (TiO2) and tungsten oxide (WO3) films are being prepared from colloids or sol-gel chemistry with high porosity and high surface area as functional layers for a photoelectrochromic device in lab scale. We have, for the first time, successfully developed a PEC device with conventionally sputter deposited TiO2 and WO3 films. This coating technique is attractive due to the well documented upscaling capability and industrial viability for window applications. The functional layers WO3 and TiO2 were deposited onto fluorine doped oxide (F:SnO2) coated glass . Characterization of WO3 and TiO2 was performed in an electrochromic cell and in a dye solar cell, respectively. Three types of PEC devices with different layer configuration were constructed and their performance based on visual transmissions was compared. In best case, the visual transmission could be switched from 61 down to 15% in 30 min under 1.5 A.M. illumination.