Tungsten Oxide Electrochromic Display

We have constructed tungsten oxide (WO₃) electrochromic displays (ECDs) with the display characters having a seven segment format. The displays are electrochemically symmetric with both the counter electrode and display electrodes composed of WO₃. The WO₃ was deposited using a variable geometry angle evaporation technique to obtain highly porous electrodes. Several lithium salts in various organic electrolytes have been used with the predominant number of displays filled with lithium hexafluoroarsenate (LiAsF₆) dissolved in acetone. Either ZrO₂ felt or sinterred Al₂O₃ has been used as a porous, white background material to the display segments. Response times of the displays vary with electrode size from approximately 200 ms for 4 mm digits to approximately 1 s for 25 mm digits. The displays exhibit cycle lifetimes in excess of 10⁶ cycles.