Quasi-symmetric electrochromic device for light modulation.

A new quasi-symmetric electrochromic device is described for transmission modulation of a switchable window. The calculation technique to design such an electrochromic window for transmission (or reflection) modulation is applied to the (electrode/WO(3)/electrolyte/WO(x)/electrode) system. Advantages and limits of such a quasi-symmetrical system are also discussed.

Optical properties of sol-gel spin-coated TiO(2) films and comparison of the properties with ion-beam-sputtered films.

Transparent and optical-grade TiO(2) coatings were prepared by sol-gel spinning and ion-beam sputtering techniques. We investigate process parameters for the fabrication of sol-gel spin-coated TiO(2) films exhibiting high optical quality comparable with that of ion-beam-sputtered TiO( 2) films. X-ray diffraction studies showed the sol-gel-deposited films to be amorphous for heat treatments below 350 degrees C, whereas the ion-beam-sputtered films were slightly crystalline and exhibited the anatase structure. The refractive index and the extinction coefficient were evaluated from transmittance characteristics in the ultraviolet, visible, and nearinfrared regions. Transmission spectra and ellipsometric measurements showed that spin-coated films were essentially optically equivalent to those prepared by ion-beam sputter deposition.

Tungsten oxide films by reactive and conventional evaporation techniques.

Tungsten oxide films (WO(3)) are deposited by thermal evaporation techniques using the starting materials of tungsten (W) and tungsten oxide (WO(3)). By varying deposition parameters, three main types of WO(3) film exhibiting different optical properties form. These are blue, gray, and colorless films. The samples are characterized optically and morphologically. Blue-colored samples exhibit a broad selective absorption peak around 1000nm. Absorption of gray-colored samples spreads out in the visible region in an exponential form. The refractive indices of samples are between 1.9 and 2.1. The energy gap of blue and colorless samples is 3.32 eV, but that of the gray-colored samples is 3.18 eV and smaller. X-ray diffraction studies reveal that evaporated WO(3) films are amorphous. Fourier transform infrared spectra of samples were studied to evaluate bond properties. Colorless near-stoichiometric tungsten oxide films exhibit three absorption peaks in the 1000-600-cm(-1) window. These peak locations, in terms of cm(-1) window. These peak locations, in terms of cm(-1), are 669,737, and 813. In the colored samples, these three absorption peaks split into two peaks ~20 cm(-1) apart.

Optical properties of spray-deposited tin oxide films.

Optical properties of spray-deposited tin oxide (TO) films are studied here. Optical grade TO films were deposited using monobutyl tin chloride and dibutyl tin diacetate solutions. The refractive index and extinction coefficient, n(lambda) and k(lambda), respectively, and film thickness of TO films are evaluated from spectrophotometric transmittance characteristics examined in the visible and UV regions. Since the interference effects are suppressed by the optical absorption in the near-IR region, both reflectance and transmittance spectra are used to evaluate n(lambda) and k(lambda) values. Spray-deposited TO films are found to be an indirect band gap material exhibiting an absorption minimum at ~1.0 microm (k less, similar 10(-3)), an energy gap at ~3.7 eV. A transition from a bounded electron model to a free electron model occurs at lambda approximately 1.4 microm.