Development of electrochromic devices of tungsten oxide thin film integrated with p-i-n photodetector

In this paper, a new electro-chromic device (ECD) is developed by tungsten oxide (WO3) thin film integrated with a-Si1-xGex:H pin photodetector. With the addition of the palladium (Pd) film to ionize hydrogen gas, the WO3 thin film will react with hydrogen ion and transfer from transparency to blue color. This color change will degrade the absorption of light with wavelength larger than blue color. First, we determine the most suitable condition (by increasing the partial oxygen pressure) to produce a-WOx films, thus offering a good electro- chromic performance for opto-switching applications. Then, the photo current generated by a-Si1-xGex:H pin photodetector will be lowered down, thus detecting the existing of hydrogen gas. Especially, the WO3-pin hydrogen sensor also shows highly selectivity with hydrogen gas to separate from CO and C2H5OH gases.