Showing papers on "Electrochromism published in 1981"

A Model for Electrochromic Tungstic Oxide Microstructure and Degradation

Abstract: Despite much investigation of the electrochromic (EC) coloration process in films, such displays have not yet become commercially viable because of limited useful device life. Device degradation occurs by film dissolution on the shelf and erosion during cycling. Water plays a crucial role in both efficient coloring/bleaching and in film degradation. To better understand the degradation process and the role of water, dissolution of EC films in aqueous media was studied. The results strongly suggest that EC films formed by evaporation are amorphous molecular solids consisting of trimeric molecules bound weakly to each other through water‐bridge, hydrogen, and van der Waal's bonding. The nature of this microstructure is responsible for the high solubility. Films subjected to ion bombardment show decreased dissolution rates as well as decreased electrochromism and, while amorphous, are believed to have a random network rather than molecular microstructure.

Electro-optical device and electro-optical light controlling device

Abstract: An electro-optical device comprising an electrolyte layer held between a pair of electrodes and an electrochromic material placed on at least one of said electrodes, wherein said electrolyte layer comprises an organic material and a chelating agent and an electro-optical light controlling device comprising an electrolyte layer held between a pair of transmissive electrodes and an electrochromic material placed on at least one of said electrodes; wherein said electrolyte layer comprises a non-liquid material of an adhesive or tacky high polymer and a material having coordinating function to a metal.

Improved Electrochromic Behavior of Reactively Sputtered Iridium Oxide Films

Abstract: We report deposition parameters for improved electrochromic behavior of reactively sputtered iridium oxide films (SIROF's). When operated in electrolyte, SIROF's deposited under these conditions may be bleached to a state exhibiting, to within experimental error (<0.4%), zero transmission loss in the visible. SIROF's which can be fully colored to an optical density (OD) of 0.45 (single pass), show a response time for coloring or bleaching (through a ΔOD of 0.3) of 40 msec under constant voltage address. This may be reduced to 20 msec in each direction if IR compensation is employed. Preliminary data show no difference in color/bleach cycle lifetime from that of SIROF's deposited under slightly different conditions. No change in contrast is perceivable after cycles at room temperature.

Electrochromic recording paper

Abstract: A medium for electrochromic recording is provided by treating paper with a water soluble leuco methylene blue compound having the formula ##STR1## wherein R is a sulfonated aromatic or sulfonated aliphatic moiety.

Cathodic Electrochromism of Lutetium Diphthalocyanine Films

Abstract: Cathodic electrochromism of lutetium diphthalocyanine films on insulating substrates was investigated by a moving‐boundary technique. Reduction occurred by injection of electrons from a gold contact and cations from a liquid electrolyte. Light blue products formed with aqueous or organic solutions of alkali metal salts, while a dark violet product formed with aqueous hydrochloric acid. The dark material had a charge‐carrier mobility of and an estimated bulk resistivity of 1800 Ω‐cm. Reduced forms of the dye appear to be solid cation conductors.

Investigations into the Electrochromism of Lutetium and Ytterbium Diphthalocyanines

Abstract: A comparison was made between the infrared, electronic, and electron spin resonance spectroscopic properties of lutetium and ytterbium diphthalocyanines, in the solid state as analytically pure powders, and after vacuum sublimation as thin deposited films. No significant differences were observed. Spectroscopic analysis of the sublimed films during electrochromic changes showed that the lutetium and ytterbium complexes behaved in a similar manner. Both gave identical variations in their electronic spectra with potential. Electron spin resonance data demonstrated that the oxidative color change is not associated with a change in paramagnetism, although the shape of the signal from the lutetium complex was altered upon oxidation. The ytterbium complex displayed no ESR signal before or after electro‐oxidation.

Volume Changes Induced by the Electrochromic Process in Sputtered Iridium Oxide Films

Abstract: We report volume changes induced by the electrochromic process in sputtered iridium oxide films (SIROF's). We show that SIROF's expand on incorporation of water. The rate of water uptake is greatly increased by initial potential cycling, i.e., coloring and bleaching. Hydration increases the kinetics of electrochromism by about an order of magnitude. We show also that electrochromic coloring and bleaching reversibly modulates the thickness of partially hydrated SIROF's. As‐deposited SIROF's significantly contract upon initial cathodic bleaching which supports the anion mechanism of electrochromism in iridium oxide films.

Electrochromic display device

Abstract: PURPOSE:To realize an electrochromic display device which has small variations in electrode potential, low resistance and stability to an electrolyte, and to simplify a process of manufacturing electrodes, by forming counter electrodes by using a carbon-mixed conductive silicone rubber compound which sets at the normal temperature CONSTITUTION:An electrochromic display device (ECD) has a display substrate 1 equipped with a transparent substrate 11, a transparent conductive layer 12 adhered to one surface of the transparent substrate 11, and an electrochromic material film 13 provided on the surface of the transparent conductive layer 12, and counter electrodes 8 arranged opposite the side of the electrochromic material film 13 of the display substrate 1 across and electrolyte 5 The counter electrodes 8 are made of a carbon-mixed conductive silicone rubber compound which sets at the normal temperature or by being heated The ECD having the counter electrodes like these has less variations of electrode potential, low resistance and chemical stability to the electrolyte because of the advantage of a carbon electrode, and a process of manufacturing the counter electrodes is simplified

The Electrochromic Properties of Thermally Decomposed Films of an Organic Tungsten Compound

Abstract: The electrochromic properties of thermally decomposed films of an organic tungsten compound are investigated. The films are prepared by spin-coating a toluene solution of hexaphenoxy-tungsten onto transparent conductive substrates and thermally decomposing the coated films in air. Films decomposed at relatively low temperatures (about 200°C) show good electrochromic properties, comparable to ordinary vacuum evaporation films. The write-erase property of the film becomes poorer as the decomposition temperature is increased. This degradation is due mainly to crystallization of the tungsten oxide.

Electrochromic display element

Abstract: PURPOSE:To expand the available surface area and to provide a high-speed responding property by making the electrochromic material layer porous. CONSTITUTION:Benzyliologen is used as an EC substance, a water-insoluble polyelectrolyte of vinyl polymer having a quat. ammonium salt structure in the side chain is used as a high molecular substance, and they are mixed in 1:2 molar ratio and dissolved in methanol to prepare a methanol soln. Finelly powdered azobisisobutyronitrile as a thermally decomposable org. foaming agent is added to the soln. and uniformly dispersed. The dispersion is applied thin and uniformly to an SnO2 display electrode 2 on a transparent glass plate 1 by means of a spinner, and by evaporating the solvent, a high molecular EC layer is formed. The foaming agent in the layer is then decomposed by heating to 90- 100 deg.C to obtain a porous filmlike EC layer 6. An ECD element is fabricated using the resulting glass substrate, and the element is filled with an aqueous K2SO4 soln. 7. By applying a DC voltage to the ECD element using the display electrode as a cathode, the color of the EC layer is turned purple, and by reversing the applied voltage, the color is returned to the original white.

Electrochromic Display Device Based on Amorphous WO 3 and Solid Proton Conductor

Abstract: An amorphous WO3 electrochromic display device (a-WO3ECD) employing a solid proton conductor was investigated. The resistivity of the solid proton conductor composed of p-toluenesulfonic acid (p-TsOH) and urea (1.2:1 in molar ratio) was 102~103 Ω cm at a relative humidity of 60% (20°C). The a-WO3ECD using the mixture of p-TsOH/urea and glycerin (20 wt.%) exhibited satisfactory EC performances such as response time (0.4 s) and open-circuit memory (over 2 hours). The most attractive feature of the ECD was an excellent visual appearance in a white and diffuse background of the solid electrolyte layer.

Electrochromic display device

Abstract: PURPOSE:To obtain a long-life display device which prevents coloring by reduction of transparent electrodes, dislodging thereof from a transparent electrode, etc. by coating the surface of the transparent electrodes of an electrochromic display device (ECD) with a transparent protecting film which is electrochemically inert. CONSTITUTION:After transparent electrodes 2 consisting of metal oxide such as In2O3 are formed on a transparent substrate 1, a transparent protecting film 3 such as gold or silver which is electrochemically inert is formed on the electrodes 2 to about 150Angstrom thickness by a vacuum vapor deposition method, a sputtering method, etc. An EC layer such as WO3 is formed on the film 3, then a substrare 7 having a counter electrode 6 and the substrate 1 are sealed by means of a spacer 8 by sandwiching a solid, semi-solid or liquid electrolyte therebetween. Thus coloring of the electrodes 2 on account of their convertion to the metal by reduction, generation of H2 or the like and the stripping of the electrodes from the substrate 1 are prevented.

Observation of electrochromism in solid‐state anodic iridium oxide film cells using fluoride electrolytes

Abstract: Thin film cells of composition SnO2/AIROF/fluoride/Au have been constructed, where AIROF is anodic iridium oxide film and fluoride is PbF2 on PbSnF4. These devices exhibit reversible electrocoloration and bleaching, with response times as low as 0.1 sec. The behavior of these cells is consistent with the anion insertion mechanism for AIROF electrochromism.

The influence of metal overlayers on electrochromic behavior of Wo3 films

Abstract: Metallic overlayers have been deposited on vapor-deposited WO3 to control the kinetics of coloration and bleaching in a WO3-liquid electrolyte electrochromic cell. These over-layers, when porous, have been found to increase the rate of coloration/bleaching and the proton transfer rate at the WO3-electrolyte interface, when appropriate voltages were applied. This effect has been characterized with potentio-static and galvanostatic measurements and compared to the coloration and bleaching of WO3 (without metallic overlayers). Coloration of WO3 films is influenced at short times by resistance and electric field effects, in disagreement with the general assumption of high conductivity in vapor-deposited WO3. The rate of coloration was also influenced by mixed barriers at the WO3-electrolyte interface. The barriers consist of a Schottky barrier at the WO3 surface and a Helm-holtz double layer. The coloration and bleaching mechanisms for WO3 with overlayers have been discussed based upon dif-fusion of electrons through the WO3, WO3-overlayer interface, or the SnO2-WO3 interface, and proton diffusion at the WO3-electrolyte interface. Resistance effects in the WO3 were found to be reduced by the overlayer. Electron injection in WO3 occurred both at the SnO2 and the overlayer inter-faces, thus increasing the rate of proton transfer, and the rate of coloration/bleaching.

Electrochromic device containing acid copolymer electrolyte

Abstract: In electrochromic devices having a layer of electrochromic material, eg tungsten oxide, in contact with a polymeric electrolyte layer, the stability and speed of the device are improved by using a copolymer of 2-acrylamido-2-methylpropanesulfonic acid and vinyl sulfonic acid as the polymeric electrolyte

Electrolytic apparatus having a stable reference electrode and method of operating such apparatus

Abstract: Electrolytic apparatus employing a reference electrode, e.g. an electrochromic display of the type employing potentiostatic control of write or erase operations, has at least one reference electrode on which a predetermined coating thickness of electrochromic or other electrodepositable material is maintained or replenished by intermittent connection of the electrode to a source of write current. Such a coated reference electrode has a stable potential with respect to the solution which is necessary for potentiostatic control. Two such reference electrodes may be used alternately such that one is being erased and rewritten while the other is connected as a reference.

Matrix‐addressable electrochromic display cell

Abstract: We report an electrochromic display cell with intrinsic matrix addressability. The cell, based on a sputtered iridium oxide film (SIROF) and a tantalum‐oxide hysteretic counterelectrode, has electrochromic parameters (i.e., response times, operating voltages, and contrast) similar to those of other SIROF display devices, but in addition, has short‐circuit memory and voltage threshold. Memory and threshold are sufficiently large to allow, in principle, multiplexing of electrochromic display panels of large‐screen TV pixel size.

Electrochromic display using rare-earth diphthalocyanines and a low-freezing-point electrolyte

Abstract: An electrochromic display utilizing a rare-earth diphthalocyanine complex as the electrochromic material and a low-freezing-point aqueous solution of a metal chloride as the electrolyte is disclosed. Displayed information can be switched in less than 50 milliseconds. The display has multicolor and color reversal capabilities even at very low temperatures.

Materials for electrochromic display devices

Abstract: A display device containing an electrochromic solution comprising a para substituted triphenylamine compound having the formula ##STR1## wherein R is lower alkoxy, lower alkyl or halogen.