經過以上兩部份的各層材料分析後，由其中選出製備電致變色元件的最佳化參數。在研究最後利用選出之參數成功製備出可撓性電致變色元件。 ;WO3 is known to be an electrochromic material which can switch its color between transparent (bleach state) and dark blue (color state) by externally applied voltages. In this study, a stack of IZO/NiO/Ta2O5/WO3/IZO electrochromic device was fabricated on flexible substrate (polyethylene terephthalate, PET) by sputtering. Before stacking all layers, each material was separately deposited on a substrate and tested for their structure, compositions, properties and functions. These characterizations for materials are carried out by the following instruments: surface profiler and FE-SEM to inspect the thickness and surface morphology; XRD and Raman spectrometers to examine microstructures; EDX and XPS for the study of chemical compositions; UV-visible-NIR spectrometer for the assessment of optical properties; 4-point probe and Hall effect sensor to measure the electrical resistivity. The electrochromic function was achieved by the chemical insertion of cations (Li+) and electrons into WO3 and NiO layers before stacking. The potential static and cyclic voltammetry then is used to test the efficiency of color change in the devices. Based on the transparency of films by UV-visible-NIR spectroscopy, coloration efficiency and energy consumption in electrochromic function, we can determine the optimal sets of process parameters in sputtering. These parameters are crucial in the fabrication of flexible electrochromic devices by current PVD technologies for the display in mobile devices.