01789nas a2200205   4500008004100000245005300041210005300094260001200147300001000159490000800169520118600177653001801363653002901381653001901410653001901429100002301448700002301471700001701494856007201511       1996                        eng d00aOptical Indices of Electrochromic Tungsten Oxide0 aOptical Indices of Electrochromic Tungsten Oxide  c08/1997  a10-160 v3063 a<p>Tungsten trioxide (WO<sub>3</sub>) is the most widely used material for the active layer of electrochromic devices. Knowledge of the complex refractive index over the range of coloration states is required for device design. Optical constants of WO<sub>3</sub> over the whole solar spectrum were determined as a function of injected charge. Films of WO<sub>3</sub> were prepared by electron-beam evaporation, then colored in several steps by reduction with lithium (Li) up to 68 mC cm<sup>-2</sup> µm<sup>-1</sup> injected charge. Measurements included variable-angle spectroscopic ellipsometry and spectroscopic transmittance and reflectance at normal incidence. Analysis was complicated by the fact that a transparent-conducting layer of indium tin oxide (ITO) was required to perform lithiation. Optical indices of the glass substrate and ITO transparent conductor were determined separately and then fixed in the model. The indices of WO<sub>3</sub> could then be extracted from measurements on the complete structure. A parametric dispersion model corresponding to Gaussian broadening of the oscillators was used to represent the dielectric response of WO<sub>3</sub>.</p>10aColored state10aComplex refractive index10aelectrochromic10atungsten oxide1 avon Rottkay, Klaus1 aRubin, Michael, D.1 aWen, Shi-Jie  uhttps://facades.lbl.gov/publications/optical-indices-electrochromic