Electrochemical Analysis of Photoelectrochromic Device Combined Dye-Sensitized Solar Cell

In this study, the photoelectrochromic device (PECD) is combination of dye-sensitized solar cell with electrochromic device (ECD) on flexible ITO/PET substrate. First, the presintering titanium dioxide was fabricated on flexible ITO/PET substrate by a screen-printing technique. Second, the tungsten trioxide (WO3) thin film was fabricated by radio frequency sputtering as electrochromic layer with different working pressures, which obtain optimal parameters in order to improve property and applied to PECD. The transmittance variation (Delta T%), optical density change (Delta OD), and coloration efficiency of optimal WO3 thin film which applied to flexible ECD and PECD were investigated. In addition, the electron transfer property of flexible PECD was analyzed by electrochemical impedance spectroscopy under dark and illumination. The Nyquist diagram indicates that the difference between dark and illumination is a diffusion phenomenon, and the charge transfer resistance between electrode and electrolyte can be observed. According to Bode plot, the phase value of flexible PECD is decreased under illumination. It indicates that the mobility of charge increases at the interface which is between titanium dioxide (TiO2) layer and electrolyte. Through Nyquist diagram and Bode plot, we can assert that the performance of the WO3 thin film which sputtered at 30 mtorr and applied to flexible ECD and PECD could obtain the optimal characteristics.