Quasi-Solid-State Electrochromic Cells with Energy Storage Properties Made with Inkjet Printing

Abstract

In common commercially available electrochromic glass panes, the active materials such as WO3 and NiOx films are typically deposited by either physical vapor or sputtering under vacuum. In the present studies, we report on the inkjet printing method to deposit both electrochromic and ion storage electrode layers under ambient conditions. An ion storage layer based on cerium modified TiO2 and electrochromic nanocrystalline WO3 were both prepared under the wet method and deposited as inks on conductive substrates. Both compounds possess porous morphology facilitating high ion diffusion during electrochemical processes. In particular, the ion storage layer was evaluated in terms of porosity, charge capacity and ion diffusion coefficient. A scaled up 90 cm2 electrochromic device with quasi-solid-state electrolyte was made with the aforementioned materials and evaluated in terms of optical modulation in the visible region, cyclic voltammetry and color efficiency. High contrast between 13.2% and 71.6% for tinted and bleached states measured at 550 nm was monitored under low bias at +2.5 volt and −0.3 volts respectively. Moreover, the calculated energy density equal to 1.95 × 10−3 mWh cm−2 and the high areal capacitance of 156.19 mF cm−2 of the device could combine the electrochromic behavior of the cell with energy storage capability so as to be a promising candidate for future applications into smart buildings.