Abstract: The optical absorption and contrast obtainable in electrochromic devices are enhanced by the appropriate construction of such devices. This construction includes tailoring the electrochromic electrode to produce a desired optical path length while at the same time adapting the surface of this electrode so that incident light strikes it at angles other than 90 degrees.

Abstract: Electrochromic devices based on anodic iridium oxide as the electrochromic material have been made. These devices exhibit long term stability, memory, and good response times, e.g., less than 80 msec. for reflectivity changes of about 70% (50 msec. for 50% changes). Devices using an anodic iridium oxide film immersed in a sulfate electrolyte have been operated for more than 6.times.10.sup.5 coloration/bleaching cycles at 0.5 Hz without noticeable change in properties. Response times and stability are also improved by a heat treatment of the anodic iridium oxide at temperatures between 40 and 100 degrees C.