COMPARISON OF TUNGSTEN AND NICKEL-OXIDE ELECTROCHROMISM IN SINGLE FILMS AND IN ALL-SOLID-STATE DEVICES

Electrochromism has been investigated in cathodically (WO3) and anodically (NiO(x)H(y)) coloured single films and two types of all-solid-state devices (ASSDs) for variable reflectance. The ASSDs contain only WO3 or both electrochromic materials respectively. Characterization was done by means of electrical and optical methods and electron spectroscopy for chemical analysis (ESCA). Spectral dependences of refractive indices n, extinction coefficients k and colouration efficiencies (CEs) are determined for single films as a function of the injected charge. The CE is 37 cm2 C-1 for WO3 and 46 cm2 C-1 for NiO(x)H(y) at a wavelength of 550 nm. On the basis of these findings, different types of multilayer ASSDs are analysed and optimized.