Room Temperature Processed Electrochromic Smart Windows with Flexible Film

Electrochromic (EC) devices, which dynamically change color under applied potential, are widely studied for use in energy-efficient smart windows. To improve the viability of smart windows, many researchers are utilizing nanomaterial, which can provide electrochromic devices with improved coloration efficiencies, faster switching times, longer cycle lives, and potentially reduced costs. We report the synthesis of nanomaterials for transparent conducting electrodes (TCE).  The smart window characteristics were measured and studied.

For fabrication of smart window, WO₃ ink was spin-coated on ITO/glass and electrolyte of ethylene carbonate, dimethyl carbonate, and lithium perchlorate was used. The counter TCE was fabricated by bar coating method with silver nanowires (Ag NW) on PET film, which has 25 ohm/sq of sheet resistance and 90% of transmittance. EC device with Ag NW TCE was assembled and sealed with epoxy. The performances of smart window were characterized with the performance of Ag NW TCE. The potential range for coloring was 1.5 – 2.5 V and the transmittance was 87 %. The bleaching was observed at -2.5 V and the transmittance was below 40 %. The flexible TCE can be applied flexible and bendable smart window with low process cost.