Thin films of Pr oxide were made by dc magnetron sputtering at different oxygen contents in the plasma. Films, ranging in color from dark orange (presumably PrO₂-like) to transparent, were made by varying the O₂/Ar ratio from 0.025 to 0.005. The electrochromic properties were studied under Li ion and proton intercalation. The charge capacity ranged from being comparable to that of W oxide for oxygen rich films to virtually zero for oxygen depleted films. The initially dark films showed strong anodic electrochromism and gave a rather neutral optical appearance in a device incorporating a W oxide film.

Cerium titanium oxide samples produced by sol-gel have been compared against sputtered and pulsed laser deposited films over a wide range of different compositions. X-ray diffraction was used to investigate the structural properties of the compound material existing in a two-phase mixture M_AO₂-M_BO₂. The optical properties were evaluated over the whole solar spectrum by variable angle spectroscopic ellipsometry combined with spectrophotometry. The spectral complex refractive index was determined for CeO₂ and TiO₂, as well as for their compounds. To reduce the large number of permutations in composition of multi-component oxides it would be useful to be able to predict the properties of the mixtures from the pure oxide components. Therefore these results were compared to those obtained by effective medium theory utilizing the optical constants of CeO₂ and TiO₂. In order to investigate the performance as passive counter-electrode in Li⁺ based electrochromic devices the films were tested by cyclic voltammetry with in-situ transmission control. Chemical composition was measured by Rutherford backscattering spectrometry. Surface morphology was analyzed by atomic force microscopy.

Voltage-time curves, concentration profiles and surface concentration of lithium for the electrochromic process at WO₃ electrodes have been calculated using a model based on constant current charge injection into electrochromic WO₃. The simulated data agree well with the experimental data for both sol-gel and sputter deposited WO₃ films. Parameters such as diffusion coefficient, series resistance and ion mobility can be estimated from theoretical fitting to the experimental data. The results are comparable to those obtained by the AC impedance measurements. The model predicts a higher concentration of Li⁺ ions in the region near the electrolyte/WO₃ interface than in the region far from the interface. For higher diffusion coefficients, a more homogeneous lithium distribution is established in the film at the conclusion of the coloration part of the cycle. This result has significant implications for the long term testing of electrochromic devices, as testing to reflect real device conditions should ensure that bleaching starts when the charge distribution in the device is the same as in a window which has been colored for several hours. It is well known that Li_xWO₃ is not reversible for x greater than 0.4. The contours of diffusion coefficient in charge density-current density plane obtained from the model show that for a given current density a lower diffusion coefficient corresponds to a smaller allowable amount of charge injection for a reversible cycle, while for a given diffusion coefficient a smaller current density allows a larger amount of charge injection. This gives a quantitative way to determine appropriate operational limits for electrochromic devices.

The preparation and optical properties of sol-gel deposited iron oxide films are investigated in this study. The films are deposited on glass by spin-coating from polymeric sol-gel solutions. The coating solutions were prepared from Fe(OCH₃H₇)₃ and isopropanol. Fe₂O₃ films were obtained at a firing temperature 180 degrees Celsius. The films were characterized by x-ray diffractometry (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and UV-Vis spectroscopy. The electrochemical properties of the films were studied in 0.5 M LiClO₄/propylene carbonate (PC) solution. The CV results showed reversibility of the Li⁺/e^- insertion/extraction process in the Fe₂O₃ films up to 200 cycles. Reduction and oxidation of the amorphous films in 0.5 M LiClO₄-PC solution caused noticeable changes in optical absorption. XRD of the films showed that they had an amorphous structure. Fourier transform infrared spectroscopy (FTIR) measurements showed that the composition of the film is Fe₂O₃. In-situ spectrophotometric measurements indicated that these films show weak electrochromism in the spectral range of 350 - 800 nm. The optical band gap is estimated to be 1.92 eV for the amorphous film. The spectroelectrochemical properties clearly indicated that cyclic stability of the iron oxide films deteriorated above 200 cycles.

The association of polyaniline, PANI, (colored in anodic polarization) and tungsten oxide (colored in cathodic polarization), separated by a solid electrolyte (PAMPS) led to interesting all solid-state electrochromic devices (ASSED). Here, significant improvements are brought to the different ASSED elements, concerning in particular the compositions of the cathodic material and of the solid electrolyte, the pH of which (in the range 0.65 - 7.65) as well as the water content (in the range 0 - 5.2%) are varied. The optimization of the thickness of the PANI layer is discussed. Another crucial point is the choice of the coloration potential (1 V or 1.2 V) allowing to associate a high coloration efficiency with an excellent stability. One knows that the blue colored PANI form appearing at high pH, which is optically the most suited to solar application, with its exciton absorption band at 2 eV, does not allow stable cycling in liquid inorganic electrolyte. On the contrary, with PAMPS, it is possible to use high pH, keeping the reversibility up to 20,000 cycles, probably in reason of the presence of free-carriers at pH as high as 4.5, which also is discussed.

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.

Based on our previous studies on the rf reactive sputtered nickel oxide films with nanostructure and its electrochromism which was supposed that electrochromic effect of the films is attributed to the reversible change of the non-stoichiometry in the nanocrystalline grain boundaries and interfaces due to the injection and ejection of Li⁺ ions, a prototype of all-solid-state NiO/WO₃ complementary electrochromic device using Li_xTaO_y thin film as inorganic electrolyte was designed and prepared. The results indicate that the solar reflectance of the device could be modulated from 0.15 in colored state to 0.60 in bleached state with excellent cyclic reversibility, durability and high response speed (less than 0.3 sec from colored state to bleached state).

Initial accelerated durability testing efforts of approximately 12" (0.3 m) x 12" (0.3 m) electrochromic windows (ECWs) suitable for buildings applications are reported. A brief overview is given about using ECWs for saving energy, the concomitant performance criteria, degradative factors that may limit ECW durability, and accelerated life testing (ACL T) methods. The ACLT methods are required because no widely accepted procedures have been established for the real-time testing ofECWs and because we cannot wait 20 or more years for the real-time evaluation for each window design. These methods include (a) the rapid but realistic I-V cyclic tests emphasizing the electrical properties, (b) the ACL T parameters that are typically used in durability tests by standards organizations, (c) the ACLT parameters we have been using to test large-area ECWs, and (d) how the results must be related to real-time testing. We present the quantitative parameters in (a) - (c) and include a detailed description of the procedures for using an Atlas XR-260 chamber with a 4' x 6' horizontal test plane on which the ECWs are positioned. The uniformity of the xenon-produced simulated solar irradiance and UV in the test plane, the variation in ECW temperatures during coloring and bleaching cycles, the stability of the chamber temperature, the methods of temperature and UV measurement, and our rationale for not using high relative humidity during testing is described. The procedures used for continuous and cyclic coloring and bleaching of the ECW s and the electro-optical measurement or the transmittance before and after cycling at 60 ±5°C in the environmental chamber are described. Typical results reported to the manufacturers of the ECW s are illustrated for the trapezoidal voltage waveform for coloring and bleaching, the corresponding luminous transmittance spectra and their changes with cycling, and the decrease in the luminous transmittance ratio resulting from ECW degradation. Keywords: electrochromic windows, accelerated life testing, large-component environmental chambers, durability criteria, largearea devices, degradation factors, degradation stresses, energy savings.

The current cost of electricity generated by PV power is still extremely high with respect to power supplied by the utility grid, and there remain questions as to whether PV power can ever be competitive with electricity generated by fossil fuels. An objective approach to this important question was given in a previous paper by the authors which introduced analytical tools to define and project the technical/economic status of PV power from 1988 through the year 2010. In this paper, we apply these same tools to update the conclusions of our earlier study in the context of recent announcements by Amoco/Enron-Solar of projected sales of PV power at rates significantly less than the U.S. utility average.

We have fabricated 13.7%-efficient CuIn_1-xGa_xSe₂ (CIGS)-based devices from electrodeposited precursors. As- deposited electrodeposited precursors are Cu-rich films. Additional In, Ga, and Se were added to the electrodeposited precursor film by physical evaporation to adjust the final composition to CuIn_1-xGa_xSe₂. Three devices with Ga/(In + Ga) ratio of 0.16, 0.26, and 0.39 were fabricated from electrodeposited precursors. The films/devices have been characterized by inductive-coupled plasma spectrometry, Auger electron spectroscopy, x-ray diffraction, electron-probe microanalysis, current-voltage characteristics, capacitance- voltage, and spectral response. The electrodeposited device parameters are compared with those of a 17.7% physical vapor deposited device.

The crystal structure of three efficient Ru-sensitizers of TiO₂ anatase nanopowders are discussed in terms of formation of two-dimensional molecular packings on the anatase surfaces. The surface areas of sensitizer molecules on the flat semiconductor surfaces are calculated. The symmetry of the (001) and (101) surface of naturally grown TiO₂ anatase has been investigated using low-energy electron diffraction (LEED) technique. The first results on the orientation of sensitizer molecules on the mostly exposed surface (101) of anatase single crystal are obtained from HRTEM data. The amount of sensitizer molecules on the mostly exposed faces of anatase nanocrystals in thin colloidal TiO₂ anatase films could be estimated using crystal structure data on both sensitizers structures and anatase surface.

The x-ray structure determination of three efficient Ru complex sensitizers of TiO₂ nanopowders was carried out. The coordination of Ru was analyzed in terms of asymmetric ligand surrounding of metal atom and influence of chelate (pi) -conjugated ligands on the bonding of Ru with ligands and on the intermolecular association of complexes. The layered character of all three studied crystal structures could be correlated with the peculiarities of their molecular structures (polarity, presence of (pi) -conjugated moieties), what opens the possibility of using of molecular engineering methods to influence the anchoring and ordering of sensitizer molecules on semiconductor surfaces.

Electrochromic films have been combined with photoelectrochemical electrodes to make a self-powered smart window. These 'photoelectrochromic' smart windows combine the advantages of photochromic films, namely that they are self- powered by the incident light, with the advantages of electrochromic windows, such as the ability to control the state of coloration externally when desired. When the windows are short-circuited, the observable process is photochromism, but the mechanism is unique and has several potential advantages over conventional photochromic films. The light absorbing process is physically separate from the coloration process, allowing each to be individually optimized. The materials constraints are greatly relaxed compared to single- component photochromic films in which one material must meet all criteria (color change, switching speed, photostability, etc.). Furthermore, since the coloration process in a PEC cell requires an external electrical current between the two electrodes, a particular state (transparent, absorbing, or imaged) can either be stored when the electrodes are at open circuit, or can be changed when the electrodes are connected. The light-absorbing function in the PEC cell is performed by a dye-sensitized semiconductor electrode that produces a photovoltage sufficient to color the electrochromic film deposited on the counterelectrode. We describe the dye sensitization process, its advantages over conventional photovoltaic devices in applications such as smart windows, and recent developments in photoelectrochromic smart windows.

A comparative analysis of photoresponse characteristics of single component photoelectrodes of WO₃ and TiO₂ and bicomponent WO₃/TiO₂ photoelectrode was performed for front and back side illumination of the films sensitized by rhodamine B and 3,3'-diethyl-9-methylthiacarbocyanine iodide. A considerable increase in the photocurrent was achieved for the bicomponent photoelectrodes in comparison with the single component photoelectrodes. Increased photocurrent was caused by a decreasing in the surface recombination of the photoinjected electrons due to an efficient removal of the electrons from the conduction band of the TiO₂ nanocrystals into the bulk of the WO₃ matrix-layer.

The technical feasibility of photocatalytic oxidation and reduction technology for the removal of hazardous chemicals or micro-organisms from contaminated water and air is well established. The heterogeneous process based on titanium dioxide photocatalysts is the most developed but homogeneous systems are also under development. Treatment equipment using fluorescent lamps as the photon source and supported heterogeneous photocatalysts are commercially available and one-sun and parabolic solar reactor designs have been demonstrated. Cost and performance of the solar processes have not yet reached levels that make them attractive relative to conventional alternatives. Cost reductions and increased performance require improvements in optical materials for reactors, reactor/collector design and materials of construction, durable catalyst materials and support structures, and significant improvement in the utilization of the solar spectrum in the photochemical processes. The current state of the art for solar reactors for treatment of contaminated air and water are presented and the opportunities for improvement are identified.

Commercially available anodized aluminum, vacuum evaporated aluminum foil, and roofing aluminum have been optically characterized in the wavelength range 300 - 2500 nm in a single beam Edwards sphere at oblique angle of incidence (60 degrees). The first two materials are long-term stable, which makes them promising to use as external reflectors. The third one is of interest because of its low cost. A model is proposed for the correction factors for the single beam sphere. A comparison between the single beam sphere and a Beckman 5240 standard spectrophotometer equipped with an integrating sphere was made. The agreement between the measurements was excellent. Furthermore, angle resolved measurements were made with a scatterometer at 633 nm at the incidence angle 60 degrees for all three samples. These data were used in a simulation model to calculate the intensity in the collector plane, assuming a semi-infinite collector and dito external reflector. A calculation of a two-dimensional ideal Lambertian sample was also made. It is shown that optically dull materials, such as roofing aluminum, which has rolling grooves that scatter light, perform equally well as optically smooth materials, provided the scatter is confined to low angles. It is also concluded that integrating sphere measurements of the specular component of diffuse sample in standard spectrophotometers are misleading. The low-angle scattering of diffuse samples also contributes to the intensity in the collector plane and should therefore also be included in the measurement. For Lambertian samples the scatter is too high and such a surface is not a feasible choice of material.

Magnesium indate powder has been synthesized from the carbonate as well as nitrate precursors by the ceramic method. Details of the preparation and preliminary characterization of the product are reported. Variation of resistivity of the sample with temperature was studied and found to be stable up to 320 degrees Celsius.

Quantum efficiency of long-base n⁺p junction silicon solar cells with SiO₂ layer deposited on the top cell, and with one-dimensional gratings etched in the cell's top is considered. It is assumed that the region where the useful absorption occurs is outside the grating region. The efficiency is independently optimized by adjusting the layer depth, and the grating dimensions, respectively. It is shown that optimum efficiency of the cells with grating is higher than that of the cell with SiO₂ layer.

Chemical bath deposition techniques for bismuth sulfide, bismuth selenide, antimony sulfide, and antimony selenide thin films of about 0.20 - 0.25 micrometer thickness are reported. All these materials may be considered as solar absorber films: strong optical absorption edges, with absorption coefficient, (alpha) , greater than 10⁴ cm^-1, are located at 1.31 eV for Bi₂Se₃, 1.33 eV for Bi₂S₃, 1.8 eV for Sb₂S₃, and 1.35 eV for Sb₂Se₃. As deposited, all the films are nearly amorphous. However, well defined crystalline peaks matching bismuthinite (JCPDS 17- 0320), paraguanajuatite (JCPDS 33-0214), and stibnite (JCPDS 6-0474) and antimony selenide (JCPDS 15-0861) for Bi₂S₃, Bi₂Se₃, Sb₂S₃ and Sb₂Se₃ respectively, are observed when the films are annealed in nitrogen at 300 degrees Celsius. This is accompanied by a substantial modification of the electrical conductivity in the films: from 10^-7 (Omega) ^-1 cm^-1 (in as prepared films) to 10 (Omega) ^-1 cm^-1 in the case of bismuth sulfide and selenide films, and enhancement of photosensitivity in the case of antimony sulfide films. The chemical deposition of a CuS/Cu_xSe film on these V_x- VI_y films and subsequent annealing at 300 degrees Celsius for 1 h at 1 torr of nitrogen leads to the formation of p-type films (conductivity of 1 - 100 (Omega) ^-1 cm^-1) of multinary composition. Among these, the formation of Cu₃BiS₃ (JCPDS 9-0488) and Cu₃SbS₄ (JCPDS 35- 0581), CuSbS₂ (JCPDS 35-0413) have been clearly detected. Solar energy applications of these films are suggested.

The feasibility of producing safety glass made from 3 mm sheet glass coated with chemically deposited CuS, ZnS-CuS, Sb₂S₃-CuS, and PbS-CuS thin films are presented. The coatings are produced on the sheet glass from dilute solutions containing metal complexes and a source of sulfide ions such as thiourea, thioacetamide, or thiosulfate. Films of thickness ranging from 0.05 micrometer to 0.3 micrometer are deposited at different temperatures, 10 degrees Celsius - 50 degrees Celsius, with durations of depositions of 1 h to 6 h. These coatings are laminated using commercially available poly(vinyl butyral) based laminating polymer sheets and clear sheet glass at temperatures of 120 degrees Celsius to 140 degrees Celsius under 10 - 12 kg cm^-2 pressure in an autoclave. The optical transmittance and reflectance spectra of the safety glasses show that a wide choice of solar control parameters are possible with these glazings: T_VIS, 2.5 - 45%; R_VIS, 10 - 25%; and shading coefficient (SC), 0.25 - 0.45.

This study covers advances in solar selective absorbers. The classes of selective absorbers are discussed along with their characteristics and physics. From much of the research and development on solar coatings in the 1970s and early 1980s only black chrome and nickel-pigmented aluminum have been largely commercially adopted. Black chrome still has the best proven overall operational characteristics for the higher flat plate collector temperatures. New types of coatings are being developed by vacuum and chemical deposition processes. Some coatings are being developed for increased temperature applications. The new coatings are known as 'black crystal,' a dendritic black nickel, TiN_xO_y, and sputtered black nickel. These coatings are emerging in the marketplace, but long-term testing has not been performed yet. The characteristics of these coatings are discussed. Several issues concerning coating and process ecology are also discussed.

The thermal oxidation of small metallic particles have been studied using infrared spectroscopy. The oxidation has been quantified by measuring the absorption of p-polarized light at 60 degree angle of incidence at the wavelengths around the longitudinal optical (LO) phonon mode of the created oxide. The case presented in this report is nickel rods embedded in alumina (Ni-Al₂O₃) exposed to temperatures in the range between 300 and 500 degrees Celsius from 1 to 500 hours. The rate of oxidation was found to be somewhat lower than previously reported for large particles and bulk nickel.

The aim of this paper is to elucidate the stability of WO₃ films for electrochromic glazing. Different properties of WO₃ films made by EB evaporation and dc sputtering are examined in terms of optical and photoelectrochemical characteristics.

The developing field of switchable chromogenic materials for smart windows and other large-area applications is discussed. A selection of switchable glazing devices that change color electrically are detailed. The types of devices covered are the electrochromic which color electronically, covering electrochromic, dispersed liquid crystal and dispersed particle glazing that switch under an applied electric field. Device structures and switching characteristics are compared. The status of prototype and commercial devices from commercial and university labs through out the world are covered. A discussion of the future of this technology is made including areas of necessary development for the realization of large area glazing in excess of 1 m².

Light valve using suspended particles was invented first by Edwin H. Land. But it could not be made to large area because it was a liquid cell containing a suspension of the particles between both transparent conductive layers. For several years, so many trials have been to make a large size of light valve. Recently we could make the light valve of large size which is film type by phase separation and/or emulsification methods. In this paper, we are introducing the light valve film made by HGI.