Showing papers on "Electrochromism published in 1990"

Large-area chromogenics: Materials and devices for transmittance control. Volume IS 4

Abstract: Chromogenic materials can alter their optical properties in a persistent yet reversible manner when subjected to a change in external conditions such as irradiation intensity, temperature, or electric-field strength. In the future chromogenic materials may be used on large scale to regulate the throughput of radiant energy for windows in buildings and cars, so that comfortable lighting and temperature are maintained without excessive air conditioning. The purpose of this book is to give a broad coverage of large-area chromogenics and to discuss their applications. The book is divided into the following areas: applications; photochromic materials; thermochromic materials; inorganic electrochromic materials; inorganic electrochromic materials; organic electrochromic materials; conductors for ions and electrons in electrochromic devices; electrochromic devices; and liquid crystals materials and devices. Separate abstracts were prepared for 33 papers in this book.

Prolonged coloration electrochromic assembly

Abstract: An electrochromic assembly useful for rearview mirrors, windows, vehicle sunroofs, information displays, office partitions and other structures which allows prolonged coloration substantially indefinitely without voltage or concentration gradient induced color segregation The assembly includes a pair of optically aligned, electrochromic devices defined by at least one transparent sheet, first and second layers of electrochromic material adjacent opposing surfaces of the sheet, the transmittance of said layers being variable when an electrical field is applied, and electrical conductors for applying such an electrical field Electrical energy is switched alternately from one device to the other for short periods of time while the remaining device is alternately bleached The switching can continue cyclically for any desired period A reflective coating may be included to allow operation as a dimming mirror Anti-reflection and index of refraction matching coatings may be included to enhance transmission Electrical energy may also be applied to both devices simultaneously to provide a deeper level of coloration than is possible from either device alone

Electrochromic Materials for optical switching devices

Abstract: The basic principles of electrochromism have been reported and discussed using the example of WO3, and some other important electrochromic materials have been described which have a number of interesting technical applications. Both compounds and materials used in ECDs were discussed and the principles of device design were portrayed, using as an example a reflective ASSD. By continuing the search for new electrochromic compounds and by further improving device design and cost optimization the applications of these materials are bound to increase.

Electrochromic and optical waveguide studies of corona-poled electro-optic polymer films

Abstract: Real-time monitoring of the corona-poling process that is used to create a bulk second-order nonlinear-optical susceptibility was accomplished by observing electrochromic shifts and intensity decreases of charge-transfer absorption bands in both dye-doped and covalently functionalized polymer films. By measuring small changes in the refractive-index anisotropy, the optical waveguiding technique was demonstrated to be a sensitive measure of the poling-induced order and its relaxation. The guest–host systems were formed from the dyes N,N-dimethylaminonitrostilbene, N,N-dimethylindoaniline (Phenol Blue), and 4-(N-(2-hydroxyethyl)-N-ethyl)-amino-4′-nitroazobenzene (Disperse Red 1), each dissolved in a poly(methyl methacrylate) matrix. The covalently functionalized polymers contained pendant para-nitroaniline (PNA) moieties. The first, poly(N-(4-nitrophenyl)allylamine), was formed from a poly(allylamine) derivative and is called PPNA. The second was based on poly(hydroxystyrene), with PNA attachment occurring between the phenol group and the PNA hydroxyethyl group; this polymer is named PHS-MENA. The final polymer is a linear epoxy (bisphenol A) with the PNA amino N atoms forming a link in the main chain; it is called Bis A-NA. A sample calculation demonstrated the use of experimental electrochromic spectral data to estimate the electro-optic coefficients.

Reduced first surface reflectivity electrochromic/electrochemichromic rearview mirror assembly

Abstract: A reduced first surface reflectivity electrochromic/electrochemichromic rearview mirror assembly provides improved glare reduction and substantially less noticeable double imaging. Preferably, the assembly includes an anti-reflective layer or coating on the outermost, front surface of the front glass substrate/panel. The coating can be a single thin film or a multiple layer thin film stack of suitable durability and index of refraction. Alternately, a gradient refractive index layer produced by surface leaching, dip coating and heating, or ion implantation may be used. The invention is especially useful in electrochemichromic mirror assemblies having a laminated front glass where unwanted total reflection and double imaging could otherwise be pronounced because of opportunities for nonparallel attachment of the multiple glass substrates.

Dip-coated TiO2CeO2 films as transparent counter-electrode for transmissive electrochromic devices☆

Abstract: The dip-coating process is an attractive way for the preparation of thin films used in the field of electrochromism. The scope of the present paper is focused on the TiO 2 CeO 2 compounds since they exhibit a reversible electrochemical insertion of lithium ions maintaining a high optical transmissivity. These films can be used as transparent counter-electrode in an all solid state electrochromic transmissive device with, for example, WO 3 as electrochromic material and a lithium conductive polymer as electrolyte.

Electronic properties of mixed valence oxide gels

Abstract: Transition metal ions exhibit several valence states. Redox reactions occur during the sol-gel synthesis of transition metal oxides. Mixed valence compounds are obtained. Their electronic properties arise from electron exchanges between metal ions in different valence states. Thermally activated electron hopping leads to semiconducting materials. Optical absorption arising from intervalence transfers gives rise to reversible optical switching. They can be used for making electrochromic display devices. Electron and ion transfers can occur at the oxide-water interface. They seem to be typical of mixed valence oxides having a spinel structure and lead to chemical modifications of both the oxide network and the solution.

DIP-COATED TiOz-CeO 2 FILMS AS TRANSPARENT COUNTER-ELECTROD E FOR TRANSMISSIVE ELECTROCHROMIC DEVICES

Abstract: The dip-coating process is an attractive way for the preparation of thin films used in the field of electrochromism. The scope of the present paper is focused on the TiO2-CeO 2 compounds since they exhibit a reversible electrochemical insertion of lithium ions maintaining a high optical transmissivity. These films can be used as transparent counter-electrode in an all solid state electrochromic transmissive device with, for example, WO 3 as electrochromic material and a lithium conductive polymer as electrolyte.

The Intercalation of Lithium in Nickel Oxide and Its Electrochromic Properties

Abstract: Under rigorously dry conditions, nickel oxide sputtered samples undergo a reversible lithium intercalation-deintercalation process which is accompanied by a net electrochromic effect. The characteristics of the process have been studied by cyclic voltammetry and by optical transmittance. The use of lithium-intercalated nickel oxide as a new type of counter-electrode in electrochromic windows is also discussed

Chromogenic materials for transmittance control of large-area windows

Abstract: Chromogenic materials have optical properties that can be changed in a persistent and reversible manner under the action of an external stimulus. They can regulate the throughput of radiant energy between widely separated extrema, and hence they can be used in future “smart windows” in buildings, cars, etc., and for many other applications. This article summarizes the state-of-the-art for: Photochromic (light sensitive) materials, with a focus on glass and spirooxazine compounds Thennochromic (temperature sensitive) materials, particularly vanadium-oxide-based coatings and “cloud gels” Electrochromic (electric charge dependent) materials integrated in multilayer configurations, with emphasis on transition metal oxide coatings and ion intercalation into these Certain liquid-crystal-based (electrically switched) materials of the guest-host as well as the polymer dispersed and encapsulated types

Material for light modulation and manufacturing processes

Abstract: An electrolytic material intended for a process relating to a light-modulating cell involving electrochromic reflection or transmission. The electrolytic material is a homogeneous mixture of solid consistency, comprising at least (a) a water-soluble salt or salts of one metal which can be cathodically deposited from an aqueous solution of one of its ions; (b) one initially water-soluble film-forming polymer resin; and (c) water. The material has ionic conductivity and deformability, and can be formed in a thin continuous layer. It has at least the functions of participating in the erasure of a picture element earlier written in the light-modulating cell, and of enabling the flow of electrical current between a working electrode and a counter-electrode during writing and erasure steps.

Structural and Electrochromic Properties of Tungsten and Molybdenum Trioxide Electrodes in Acidic Media

Abstract: In situ x‐ray diffraction (XRD) technique was employed to study unstable phases formed in sintered or anodically oxidized tungsten and molybdenum trioxide film electrodes under electrocoloration conditions in , in order to discuss their electrochromic characteristics on the basis of structural properties. The XRD patterns for tungsten trioxide film electrodes revealed that was transformed to hydrogen bronzes of in company with coloration while no structural change was observed in the anodic oxide film of . These findings supported that the electrocoloration proceeds according to the following processes: and . For the sintered film electrode, the crystal lattice was discontinuously expanded in the direction perpendicular to layers formed by octahedra by insertion of proton to the layer under electrocoloration condition: . The anodic oxide film formed on a Mo plate had been already colored black‐blue, but it provided a different XRD pattern by cathodic polarization at −0.30V.

Polyaniline‐Prussian Blue Novel Composite Material for Electrochromic Applications

Abstract: Preparation et caracterisation d'un nouveau materiau composite constitue d'une electrode d'or, de platine ou d'oxyde d'etain qui est modifiee par un film de polyaniline et de bleu de Prusse

Water-soluble conducting poly(aniline) polymer

Abstract: Water-soluble conducting poly(aniline propane sulphonic acid) and its sodium salt have been synthesized by derivatization of polyaniline; multiple and reversible colour changes were observed for polymer films on indium–tin oxide coated glass dipped in a LiClO4/acetonitrile solution between –0.4 and 1.2 V vs. Ag/AgCl, and for aqueous polymer solutions between pH 1 and 10.

Solid state electrochromic devices

Abstract: An electrochromic device which comprises two conductive electrodes (4A,4B) separated by a solid electrolyte (1) and an electrochromic material (2) capable of reversible electrochromic interaction with activating electrons and/or ions furnished to it by, or by it to, the rest of the device under the influence of an electrical potential applied across the electrodes (4A,4B), characterised in that the solid electrolyte (1) in the device comprises: a) a matrix of optionally cross-linked main polymer chains, having side-chains linked to the main polymer chains, which side chains comprise polar groups, b) an ionised ammonium or alkali metal salt dissolved in the matrix and/or liquid, and c) an optional polar aprotic liquid dispersed in the matrix, and a process for the preparation thereof.

Electrochromic devices comprising metal salts in an ion conductive material

Abstract: of the Disclosure This invention is directed to an electrochromic device which comprises a colorable electrochromic matrix layer consisting essentially of certain metal salts and an ion conduction enhanser in an ion conductive material

Electrochromic device with a reference electrochromic element

Abstract: An electrochromic device is disclosed. The electrochromic device includes a pair of bases, and both a primary and a reference electrochromic element provided between the bases. The reference electrode is electrically connected to the primary electrochromic element so as to maintain the color-developing and fading potentials of the primary electrochromic element at predetermined voltages. A power regulator is also provided for driving the primary electrochromic element based in part on the output of the reference electrochromic element.

Solid-state electrochromic device with proton-conducting polymer electrolyte and Prussian blue counterelectrode

Abstract: A solid-state electrochromic device is disclosed comprising tungsten oxide-Prussian blue complementary configuration in combination with a proton-conducting polymer electrolyte.

Electrochromic element, materials for use in such element, processes for making such element and such materials and use of such element in an electrochromic glass device

Abstract: An electrochromic element useful in an electrochromic glass or mirror device and a process for making such element. The element is a five-layered structure including an electrolyte ion conducting layer interposed between first and second inorganic electrochromic layers which are interposed between a pair of conductive electrodes. The first and second inorganic electrochromic layers are different and are capable of exhibiting color-forming properties complementary to one another upon the incorporation of an alkali metal or Ag ion, a mixture of alkali metal or Ag ions or a mixture of alkali metal or Ag and hydrogen ions. The electrolyte ion conducting layer may be a copolymer of ethylene oxide, butylene oxide or methyl glycidyl ether, and optionally a small amount of allyl glycidyl ether, along with an ionizable salt, or may be a polyurethane gel forming by reacting the copolymer with triisocyanate, along with an ionizable salt. The second inorganic electrochromic layer comprises a transition metal oxide which exhibits a color change when shifting between the +2 and +3 valence states. The second inorganic electrochromic layer may be produced by an electrochemical process, a chemical process, or by a physical process. The electrochromic element may also comprise a plurality of five-layer structure in tandem, each pair separated by a substrate.

Electrochemistry and electrochromism of vanadium hexacyanoferrate

Abstract: Vanadium hexacyanoferrate (VHCF) is an electrochromic material. The deposition, characterization, and spectroelectrochemistry of films of VHCF are reported here. The electrodeposition of VHCF films is shown to involve the reduction of vanadium(V) ion in the presence of ferricyanide ion. X-ray diffraction data confirm a cubic crystal structure for VHCF, similar to that of Prussian blue. From X-ray photoelectron spectroscopy and coulometric results, coupled with other electrochemical data, we conclude that the electrochromic reaction involves only the oxidation and reduction of the iron centers in the compound

Hydrolysis of molybdenum and tungsten alkoxides: sols, powders and films

Abstract: Hydrolysis of molybdenum and tungsten alkoxides of the two series MO(OEt)4 and MO2(OEt)2 (M = Mo, W) has been studied. Hydrolysis products and the partially hydrolyzed solutions have been characterized by means of X-ray diffraction, IR, electron spectroscopy and small-angle X-ray scattering. Preparation of stable sols is reported and their structures are discussed in terms of a fractal model. While ‘tungsten solutions’ may be described as typical polymeric sols, ‘molybdenum solutions’ should be regarded as particulate sols. The reason for this difference has its origin in the structures of alkoxides and mechanisms of their hydrolysis. Sols were used for the preparation of electrochromic and photochromic films by spin-coating techniques. A coloration mechanism is discussed in terms of the percolation model. Some properties of the composite structures WO3TiO2, n-SiWO3 are also reported.

New preparation process of V2O5 thin film based on spin-coating from organic vanadium solution

Abstract: A new wet process was developed for preparing a V2O5 thin film for use in an electrochromic display device. V2O5 powder was dissolved into a mixed solution of benzyl alcohol and iso-butanol to obtain a vanadium solution, which was then spin-coated on an ITO glass followed by a heat treatment at temperatures above 300°C, preferably at 400°C. The resulting crystalline V2O5 thin film was excellent in reversibility of the electrochromism.

A Study of the Photochromic and Electrochromic Properties of MoO3 Thin Films

Abstract: The photochromic and electrochromic responses of MoO3 thin films subjecting to UV irradiation were investigated in different environments. It was found that photochromic responses were different in different chemical environments. The presence of oxygen had a detrimental effect on the photochromic responses of the films. Additionally, the irradiated MoO3 films, after biased negatively in 0.1 M LiClO4/propylene carbonate solution, showed enhancement in electrochromism when compared to the non-irradiated samples treated in a similar fashion. The MoO3 and WO3 thin films showed significant differences in photochromic responses in HCOOH and C2H5OH vapors.