Showing papers on "Electrochromism published in 1983"

Reversible oxidation and rereduction of entire thin films of transition-metal phthalocyanines

Abstract: Thin films (1000 to 2000A thick) of iron(II) (Fe), cobalt(II) (Co), nickel(II) (Ni), copper(II) (Cu), and zinc(II) (Zr) phthalocyanines (Pc) on gold or indium oxide electrodes undergo stoichiometric oxidation and rereduction. Except for FePc and CoPc, the process is essentially reversible. Chronocoulometry showed that ZnPc films oxidized to the extent of 1.21 electrons per ZnPc molecule; CoPc required 1.92 electrons per molecule. Charge compensation is attained upon oxidation by uptake of anions from the electrolyte and by expulsion of anions upon reduction. Auger electron spectrometry allowed detection of the ions and characterization of their distributions. In partially oxidized films, the anions appear to be homogeneously distributed. Oxidation seems to proceed at all grains with equal probability, with anions entering and departing along grain boundaries. Smaller anions allow full oxidation at rapid rates; larger ones inhibit the oxidation with respect to rate. Optical spectroscopy showed evidence for reorganizaton of the crystalline lattices. The rereduced form is not the same as the original material, but it can be restored to the original form by annealing at 125/sup 0/C. In cyclic oxidations and rereductions, there is a gradual loss of charge-consuming ability, apparently related to electrical isolation of small domains, perhaps grains. Themore » oxidations and rereductions are electrochromic, and the various color changes are described. 10 figures, 1 table.« less

Electrochromic Polymers Covalently Anchored to Electrode Surfaces. Optical and Electrochemical Properties of a Viologen‐Based Polymer

Abstract: Fonctionnalisation d'electrodes de platine et d'oxyde d'etain par le polymere redox derive du dibromure de {N,N'-bis [(trimethoxysilyl)-3 propyl] bipyridinium-4,4}

High near‐infrared reflectivity modulation with polycrystalline electrochromic WO3 films

Abstract: A near‐infrared reflectivity exceeding 60% at 2.5‐μm wavelength has been observed for a polycrystalline, rf sputter‐deposited electrochromic (EC) WO3 film in a deeply colored state. This reflectivity is considerably higher than that previously reported for a thermally evaporated EC‐WO3 film that was crystallized by a post‐deposition thermal anneal. The shapes of the x‐ray spectra of the two films are also different. The results of ellipsometry measurements of the optical constants provide convincing evidence for the validity of a free‐electron Drude model to explain the reflectivity modulation observed in polycrystalline EC‐WO3.

Electrochemical Properties of WO 3 · x ( H 2 O ) I . The Influences of Water Adsorption and Hydroxylation

Abstract: Electrochemcial properties of evaporated amorphous films on conductive glass substrates have been studied in organic electrolytes in order to clarify the influence of water in the films on electrochromism. Compositions of water in the film have been analyzed by using FT‐IR spectra and 1H‐NMR. We conclude that the water adsorbed in the film during the evaporation and from ambient air not only leads to a fast electrochromic reaction at first, but also reacts gradually with by hydroxylation and/or hydrolysis to shift the potential of the cathodic reaction to the negative side and that the hydroxylated film layer loses the electrochromic coloration density.

Kinetic Study of Li x WO 3 Electrochromism

Abstract: Coloring/bleaching processes of LixWO3 electrochromism were examined in terms of emf, chronoamperometry, voltammetry and ac impedance measurements. The current-potential relation was found to be ohmic in the short time region and expressed by i=(Eapp-emf (x))/R. Satisfactory fittings were obtained for chronoamperometry and voltammetry measurements on the basis of the assumption of diffusion-limited process with above i-E relation. Diffusion coefficient was estimated to be about 5×10-10 cm2/sec. It was elucidated from the detailed analysis of impedance that R was given by the summation of the resistances of solution, electrode, charge transfer and material transfer. Since it was found that the WO3 film was regarded as a large condenser with a serially connected resistor, color/bleach processes were understood as charging/discharging processes of WO3 film.

Electrochromic display element

Abstract: PURPOSE: To provide an electrochromic display element which has good memory and quick response, produces yellow color and, when combined with other color developing substances, display colors which have so far been unobtainable and makes dichroic switching possible, prepared by using an iron-cobalt cyano complex as electrode material CONSTITUTION: An iron-cobalt cyano complex of the formula (where 3≤X≤4; 2≤Y≤3) is used as electrochromic substance for at least one of electrode materials in an electrochromic display element which develops and extinguish color by redox reaction The display element has good memory and quick response and can be used for facing electrodes in place of Ir 2 O 3 and NiO When oxidized, the compd develops yellow color and when reduced, it becomes colorless Thus the compd makes possible display in yellow color which has so far been unobtainable under a stabilized condition and when combined with other color- developing and color extinguishing substances, it produces display colors which have so far been unobtainable and makes dichroic switching feasible COPYRIGHT: (C)1984,JPO&Japio

The Effect of Repeated Operation on Electrochromism in an All-Solid-State Device Using Li-Doped MgF 2 Thin-Film Electrolyte

Abstract: We have fabricated a thin-film electrochromic device consisting of WO3 and Li-doped MgF2 films. Although the device exhibited excellent coloration and bleaching response (coloration period: ~100 ms, bleaching period: ~200 ms), the following changes in the device characteristics were observed upon retreated operation: 1) bleaching was impaired, 2) spontaneous coloration increased while spontaneous bleaching decreased and 3) the threshold voltage for coloration decreased. We have found that these changes can be attributed to the change in the free energy or the Li+ ion.

Electrochromic display element

Abstract: PURPOSE:To form an oxidation coloring type electrochromic layer without coloring of the film itself in the stage of filming by using a composite material of an oxidation coloring type electrochromic material and a metallic oxide in constituting an oxidation coloring type electrochromic layer CONSTITUTION:Iridium oxide is used as an oxidation coloring type electrochromic material and tantalum pentoxide as a metallic oxide, and a film is formed from these materials by a reactive ion plating method An ion plating device has a pair of crucibles 12a, 12b, electron guns 13a, 13b for generating electron beams, a high frequency coil 14 and a holder 15 in a bell-jar 11 evacuated to a vacuum A substrate 18 formed by depositing by evaporation a transparent conductive material 17 on a glass plate 16 is fixed on the holder 15 in a way that the plate 16 faces the holder 5 Oxygen O2 is introduced as reactive gas into the bell-jar 11 An iridium metal 19 is installed as a vapor deposition source in the crucible 12a, and tantalum pentaoxide 20 is installed as a vapor deposition source in the crucible 12b The element having the electrochromic layer consisting of the composite oxide of tantalum pentaoxide and iridium is thus obtd

Electrochromic display element

Abstract: Disclosed is an electrochromic display element having an electrochromic material layer (3) and an ion-conductive material layer (4) being in contact therewith, characterized in that said electrochromic layer (3) comprises a transistion metal oxide and said ion-conductive material layer (4) comprises a light-transmissive organic polymeric resin and an inorganic ion-conductive material

Solar optical materials for innovative window design

Abstract: New and innovative optical materials and coatings can greatly improve the efficiency of window energy systems. These potential materials and coatings increase energy efficiency by reducing radiative losses in the infrared, or reducing visible reflection losses or controlling overheating due to solar gain. Current progress in heat mirror coatings for glass a polymeric substrates is presented. Highly doped semiconducting oxides and metal/dielectric interference coatings are reviewed. Physical and optical properties are outlined for antireflection films and transparent aerogel insulation media. The potential for optical switching films as window elements includes discussions of electrochromic, photochromic and other physical switching processes.

Electrochromism for organic materials in polymeric all‐solid‐state systems

Abstract: This letter reports a new electrochromic polymeric film system consisting of a polymer, an electrochromic (EC) dye which is pyrazoline or tetrathiafulvalene (TTF), and lithium perchlorate (LiClO4) The electrochromic cell structure is glass/ITO/polymeric EC film/Au film The cell using pyrazoline as an EC dye exhibited yellow coloration at 10 V and the cell with TTF exhibited red coloration at 35 V These cells exhibited memory

Electrochromic display device

Abstract: An electrochromic display device containing at least two electrodes and electrolyte in contact therewith is disclosed, wherein the electrolyte is an electrolytic solution which has been gelated by polymer.

Physical Structure and the Electrochromic effect in Tungsten Oxide Films

Abstract: In all previous studies of tungsten oxide films it has been implicitly assumed that the film is uniform except for grain boundaries in polycrystalline films. In this study we show that amorphous tungsten oxide thin films contain highly anisotropic void networks which not only dominate their physical structure but also control their electrochromic behaviour. The void network structure is controlled primarily through ion bombardment of the growing film during deposition while the film stoichiometry HyWO3−x is controlled by the reactive sputtering processes of tungsten in Ar/O2/H2 atmospheres. The evolutionary growth model of physical structure was studied in detail by both transmission and scanning electron microscopy. On the basis of physical structure-property correlations we are able to consistently explain the basic electrochromic characteristics and chemical stability of the films. Such information leads to better understanding of the problems and limitations inherent in thin film electrochromic devices.

Electrochromic Materials For Controlled Radiant Energy Transfer In Buildings

Abstract: Windows and building envelopes with an externally variable light transmission can be used to reduce significantly heating and cooling loads. Thin film, large area electrochromic structures are conceptualized which would permit reversible aperture control through applica-tion of small dc electrical currents. The structures have the generalized geometry TEC/EC1/FIC/EC2/TEC, where TEC is a thin transparent electrical conductor, EC1. and EC2 are complementary electrochromic layers, and FIC is a fast ion conductor. Measurements of the optical properties of the polycrystalline electrochromic oxide HxWO3 show large increases in reflectivity on increasing x, an effect not pronounced in the more frequently investigated amorphous material. The variation of the optical constants with x are used to demonstrate the dominance of free electron scattering in determining the optical properties. It is therefore concluded that electrochromic windows based on polycrystalline electrochromic layers may be operated in a reflectivity mode, which has several important advantages over variable absorption operation.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Electrochromic display body

Abstract: PURPOSE:To obtain a matrix display type electrochromic display body (ECD) causing no cross-effect phenomenon by forming one of transparent and counter electrodes on the display side as a divided electrode, diving a solid or semisolid proton donor layer into parts, and filling the gaps with an insulating layer. CONSTITUTION:Tungsten oxide is vacuum-deposited on a display section by an electron beam heating system to form an EC layer 4. Antimonic acid as a solid electrolyte is kneaded with glycerol and water in 5:1.2:0.5 weight ratio to prepare ink, and a PS layer 5 is formed by screen printing with the ink and drying. The layer 5 is coated with a mixture of 10 parts electrically conductive carbon-base paste with 3 parts Prussian blue as a reversibly oxidizable substance by screen printing to form a reversibly oxidizable counter electrode 6. After forming a collector layer 7 with electrically conductive Ag-base paste, the layer 7 is coated with a photosetting resin adjusted to V4-V5 viscosity with a Gardner-Holdt viscometer by screen printing, and the resin is immediately photoset by exposure to an ultraviolet metallic halide lamp of 3kW set apart from the resin by 20cm distance for about 10sec to form an intermediate insulating layer 8. Leads 10 are then formed by screen printing with electrically conductive Ag-base paste.

Viologen‐based electrochromic light scattering display

Abstract: In conventional viologen‐based electrochromic displays, contrast changes are achieved by modulating light using the optical absorbance of the electrodeposited film. A display technique is described which uses instead the light scattering properties of the same film to produce intensity variations. Under practical conditions, contrast ratios of 60:1 can be achieved by electrodepositing 1 mC cm−2 of the n‐heptyl viologen cation radical with a 1‐ms current pulse. The display also has memory and is compatible with integrated drive schemes.

Modification of vapor‐deposited WO3 electrochromic films by oxygen backfilling

Abstract: The effects of oxygen backfilling during WO3 vapor deposition have been studied. Rutherford backscattering and secondary ion mass spectrometry were used to show that the O/W ratio and alkali/W ratio were increased by oxygen backfilling. The durability of the deposited films in H2SO4 was shown to be limited by two mechanisms—a general uniform film dissolution and an interfacial attack resulting in delamination. The amount of degradation was reduced as the O/W ratio increased. the electrochromic coloration speed remained unchanged, the bleaching speed and self‐erasure rates were faster, and the maximum optical density was lowered for oxygen‐enriched films. The mechanisms by which these modifications were achieved are discussed.

Poly (2,2' - bithiophene) : an electrochromic conducting polymer

Abstract: We present the optical properties of poly (2,2' bithiophene) and show that this material exhibits electrochromic behavior.

Phenothiazine leucodyes for electrochromic recording

Abstract: An electrochromic recording substrate comprising bromide ions and a leucodye having the structure ##STR1## wherein R is lower alkyl, lower alkoxy, lower thioalkyl, lower dialkylamino, or diarylamino.

Electrochromism in a Thin-Film Device Using Li 2 WO 4 as an Li-Electrolyte

Abstract: A thin-film electrochromic device using Li2WO4, which is shown to be an Li electrolyte by the fact that the coloration response is independent of the atmosphere, is found to exhibit quick response (coloration: 50 ms, bleaching: 200 ms). The spontaneous coloration is suppressed by the deposition of a WO3 film at low pressure (10-6 Torr), and by using a metal with a small work function as the counter-electrode. The threshold voltage for coloration increases as the work function of the counter-electrode material decreases. Supressions of the spontaneous coloration and the threshold voltage shift are induced by the potential difference between the WO3 and the counter-electrode introduced by the difference in the Fermi levels. Complete bleaching of the device is achieved in a device with a WO3 film deposited at 10-6 Torr at a substrate temperature of 160°C, while it is not achieved in a device with a WO3 film deposited at 10-4 Torr. This suggests that Li2WO4 is colored by proton injection from WO3 into Li2WO4, which arises from the electrolysis of water in the WO3 film deposited at high pressure.

Electrochromic display element

Abstract: PURPOSE:To obtain an EC display element which permits setting of optical colors according to purposes of use by providing display electrodes and a counter electrode, providing transition metallic oxides as an EC layer between the transparent electrode films and a solid insulating layer, and heat-treating the same at prescribed temps. CONSTITUTION:Transparent display electrodes 2 of ITO films or the like are provided on a transparent glass substrate 1. For example, WO3 is selected from EC materials which are transition metallic oxides such as WO3, V2O5, MoO3, TiO2, and is vacuum-deposited to provide a coloring layer 3. Thereafter, said layer is treated under heating for 5 minutes at 300-400 deg.C to form a white- colored thin film. A solid insulating layer 4 (CaF2) is provided thereon and a counter electrode 5 formed with Au is laminated on this layer, whereby an EC display element is obtained. If positive potential is applied on the electrodes 2, the heat-treated WO3 coloring layer 3 generates the wavelength-transmittance characteristics changing from transparency to a pale yellow color. Even when not only the layer 3 but a V2O5 layer is used, the original color changing arises. Thus the EC display device having more variety in colors than in the prior art is obtained by using the transition metal oxides.