All inorganic oxide solid state thin film electrochromic devices with variable reflectance

All inorganic oxide solid-state thin-film electrochromic (EC) devices with variable reflectance were fabricated by electron beam (EB) evaporation deposition technology. Multilayer thin film configuration was deposited in NiOx/SiOx/WO3/Al order onto a glass substrate precoated with indium tin oxide (ITO) transparent conductive layer. We designed and developed a comprehensive test system to measure the optical, electrical and electrochromic characteristics of such a device. A composite virtual instruments in the system may generate a square wave or triangle wave to drive EC unit, and also can collect and store all optical and electrical data occurred in EC processes. For reflective EC devices, their optical switching and modulating characteristics, response and open- circuit memory behavior and optical reflective spectra are investigated. Reflective changes as large as 60% at 633.3 nm wavelength are obtained. Optimal coloring and bleaching time are 3.5 sec and 2 sec respectively. Several hundreds coloration and bleaching cycles of such devices have been carried out without any degradation. All results indicate that such a device is highly suitable for potential applications such as automotive rear-view mirror and other variable transmittance devices.