Showing papers on "Electrochromism published in 2001"

Hybrid Organic–Inorganic Materials—In Search of Synergic Activity

Abstract: This review surveys the work developed in the field of functional hybrid materials, especially those containing conducting organic polymers (COPs), in combination with a variety of inorganic species, from molecular to extended phases, including clusters and nano-sized inorganic particles. Depending on the dominating structural matrix, we distinguish and analyze organic–inorganic (OI) hybrids, nanocomposite materials, and inorganic–organic (IO) phases. These materials have been used in a wide variety of applications, including energy-storage applications, electrocatalysis, the harnessing of electrochromic and photoelectrochromic properties, application in display devices, photovoltaics, and novel energy-conversion systems, proton-pump electrodes, sensors, or chemiresistive detectors, which work as artificial “noses”.

Electrochromic Systems and the Prospects for Devices

Abstract: Many inorganic and organic materials exhibit redox states with distinct electronic (UV-vis) absorption bands. When the switching of redox states generates new or different visible region bands, the material is electrochromic. Electrochromic materials are currently attracting much interest in academia and industry for both their fascinating spectroelectrochemical properties and their commercial applications. In this review some of the most important examples from the major classes of electrochromic materials are highlighted. Examples of their use in both prototype and commercial electrochromic devices are illustrated including car mirrors, windows and sun-roofs of cars, windows of buildings, displays (see Figure), printing, and frozen-food monitoring.

Electrochromic Nanocrystal Quantum Dots

Abstract: Incorporating nanocrystals into future electronic or optoelectronic devices will require a means of controlling charge-injection processes and an understanding of how the injected charges affect the properties of nanocrystals. We show that the optical properties of colloidal semiconductor nanocrystal quantum dots can be tuned by an electrochemical potential. The injection of electrons into the quantum-confined states of the nanocrystal leads to an electrochromic response, including a strong, size-tunable, midinfrared absorption corresponding to an intraband transition, a bleach of the visible interband exciton transitions, and a quench of the narrow band-edge photoluminescence.

Switchable mirrors based on nickel–magnesium films

Abstract: A new type of electrochromic mirror electrode based on reversible uptake of hydrogen in nickel magnesium alloy films is reported. Thin,magnesium-rich Ni-Mg films prepared on glass substrates by cosputtering from Ni and Mg targets are mirror-like in appearance and have low visible transmittance. Upon exposure to hydrogen gas or on reduction in alkaline electrolyte, the films take up hydrogen and become transparent. When hydrogen is removed, the mirror properties are recovered. The transition is believed to result from reversible formation of Mg2NiH4 and MgH2. A thin overlayer of palladium was found to enhance the kinetics of hydrogen insertion and extraction,and to protect the metal surface against oxidation.

Busbars for electrically powered cells

Abstract: Edge busbars on a substantial perimeter of an electrochromic device are disclosed having electrical paths wrapping over the perimeter edge. Internal busbars interior from the perimeter are disclosed which lower the conductivity of the conductive layer of an electrochromic device. Signals supplied to the busbars to control the electrochromic device are controlled by a switching power supply that allows the maintaining of the color of the electrochromic device without application of continuous power.

Digital electrochromic mirror system

Abstract: A vehicular electrochromic rearview mirror system includes an interior electrochromic rearview mirror assembly and at least one exterior electrochromic rearview mirror assembly. Each mirror assembly includes an electrochromic reflective element that assumes a partial reflectance level in response to a signal applied thereto. A drive circuit applies a drive signal to each of the electrochromic reflective elements. The drive circuit may include a digital controller, a master drive circuit responsive to the digital controller to apply a first drive signal to one of the electrochromic reflective elements and a slave drive circuit responsive to the digital controller to apply a second drive signal to a second of the electrochromic reflective elements. The second drive signal may be derived from the first drive signal. The drive circuit may include a digital controller and a switching power supply controlled by the digital controller to produce a drive signal.

Synthesis and electrochromic properties ofmesoporous tungsten oxide

Abstract: The electrochromic properties of mesoporous tungsten oxide are described and compared to standard sol–gel films of WO3. The block copolymer template used in the synthesis was removed by solvent extraction and calcination methods, leading to mesoporous tungsten oxides which range from amorphous to crystalline depending on the removal treatment. The pores are not ordered but do exhibit a fairly regular diameter with an average size of 4 to 5 nm. The mesoporous tungsten oxides exhibit a well behaved electrochromic response and their electrochemical and optical reversibilities are better than those of the analogous sol–gel film. In addition, the mesoporous films exhibit higher rates for coloration and bleaching. The high surface area of these materials is responsible for this behavior and also leads to multiple peaks in the voltammetric scans.

Fully undoped and soluble oligo(3,4-ethylenedioxythiophene)s:spectroscopic study and electrochemical characterization

Abstract: Fully undoped oligo(3,4-ethylenedioxythiophene)s have been synthesized from polycondensation of the corresponding dibromomonomer in the presence of a catalytic Ni(0)-based complex in N,N-dimethylacetamide (DMA). HPLC analysis indicated that the material is constituted of three main oligomers which have also been clearly detected by UV-Visible spectroscopy. Due to its partial solubility in DMA, processability is improved compared to the corresponding insoluble polymer and thin films of oligomers can be deposited by evaporation. Electrochemical and electrochromic properties of undoped film have been carried out. Deep purple in its undoped state, the material becomes sky blue in the oxidized form. The mixture of oligomers was characterized by means of Raman scattering, IR absorption and X-Ray dffraction (XRD), and compared to the poly(3,4-ethylenedioxythiophene) obtained by the oxidative route.

Coupled electrochromic compounds with photostable dication oxidation states

Abstract: Coupling of anodic electrochromic compounds by a covalent bond or a bridge link which provides for electronic communication between the coupled electrochromic compounds results in coupled electrochromic compounds which exhibit greater stability as well as electrochromic activity that differs from the monomeric electrochromic compounds. Extension of the absorption spectrum into the near-infrared region of the spectrum is frequently observed. The coupled electrochromic compounds are highly suitable for use in electrochromic media used to produce electrochromic devices.

Electrochromic device having a self-cleaning hydrophilic coating

Abstract: An electro-optic device is disclosed having a self-cleaning, hydrophilic optical coating. The electro-optic device preferably forms an external rearview mirror for a vehicle. The optical coating preferably includes photocatalytic layer(s), a hydrophilic layer, and a color suppression coating. The electro-optic device is preferably an electrochromic mirror. The disclosed optical coating exhibits a reflectance at the front surface of the reflective element that is less than about 20 percent, and has sufficient hydrophilic properties such that water droplets on a front surface of the optical coating exhibit a contact angle of less than about 20°. The mirror exhibits a C* value of less than 25.

Electrode design for electrochromic devices

Abstract: An electrochromic device, such as a window or mirror, is disclosed that includes first and second substrates each having an inner surface spaced apart from one another to define a chamber, first and second electrodes carried on the inner surface of the second substrate and disposed thereon to be electrically isolated from one another, and an electrochromic medium disposed in the chamber. The electrodes may be disposed on the inner surface of the second substrate in substantially co-planar relation. Alternatively, the electrodes may be arranged in a stacked relation, with a layer of dielectric material provided therebetween.

Structure and method for fabricating an electro-optic system having an electrochromic diffraction grating

Abstract: A semiconductor structure for implementing optical beam switching includes a monocrystalline silicon substrate and an amorphous oxide material overlying the monocrystalline silicon substrate. A monocrystalline perovskite oxide material overlies the amorphous oxide material and a monocrystalline compound semiconductor material overlies the monocrystalline perovskite oxide material. An optical source component that is operable to transmit radiant energy is formed within the monocrystalline compound semiconductor layer. A diffraction grating including an electrochromic portion is optically coupled to the optical source component.

Preparation of Manganese Oxide Thin Films by Electrolysis/Chemical Deposition and Electrochromism

Abstract: Manganese oxide (MnO 3 ) thin films were deposited onto transparent and conductive tin oxide-coated glass substrates by electrochemical deposition (at 1.2 V vs. Ag/AgCl) and subsequent chemical [electrolysis/chemical (EL/C)] processing in a manganese ammine complex solution at pH 8. Characterization by X-ray diffraction (XRD) of the films revealed that the crystal structure formed in the films by EL/C deposition is assigned to γ-Mn 2 O 3 and/or Mn 3 O 3 . X-ray photoelectron spectroscopy (XPS) was also performed to focus on exchange splitting effect shown in Mn 3s spectra and peak analyses of O Is spectra of the films. From electrochemical, quartz crystal microbalance, XRD, XPS, and atomic force microseope studies, a mechanism of film growth was illustrated, featuring time course of rest potential during chemical process. The XPS data also suggested that the electrochromic behavior, turning brown and light yellow by the anodic and cathodic polarization in potassium borate buffer solution at pH 10. originates from a transformation between two oxygen groups in hydroxide (Mn-O-H) and oxide (Mn-O-Mn) accompanied by the change in valence of Mn. The repeated EC switching performance of the films was also assayed.

Organometallic Complexes for Nonlinear Optics. 24. Reversible Electrochemical Switching of Nonlinear Absorption

Abstract: The molecular inorganic compounds 1,3,5-{trans-[RuCl(dppe)2]C⋮C-4-C6H4C⋮C}3C6H3 (1), trans-[Ru(C⋮C-4-C6H4C⋮CPh)Cl(dppe)2] (2), and trans-[Ru(C⋮CPh)Cl(dppm)2] (3) exhibit reversible oxidation in solution, assigned to the metal-centered RuII/III processes. Complexes 1−3 are essentially transparent at frequencies below 20 × 103 cm-1, whereas the green complexes 1+−3+ have a strong absorption band centered near 11−12 × 103 cm-1. These absorption bands have been utilized to demonstrate facile NLO switching utilizing an optically transparent thin-layer electrochemical cell, a procedure which has applicability to evaluating the switching capability of a range of materials. This procedure has been applied to switch cubic nonlinearities, the first electrochromic switching of molecular nonlinear absorption. Oxidation of the molecules results in changes, including changes of sign, of both the imaginary (absorptive) part of the third-order nonlinearity and the real (refractive) part. Cycling between the two forms of ...

Rational design of an electrochromic polymer with high contrast in the visible region: dibenzyl substituted poly(3,4-propylenedioxythiophene)

Abstract: A dibenzyl substituted poly(3,4-propylenedioxythiophene) was designed and synthesized, and exhibited a contrast of 89% at 632 nm with switching speeds of 400 ms and coloration efficiency of 575 cm2 C−1.

Non-flammable electrolytes

Abstract: Improved electrolytes for application in electrical storage devices, such as batteries and capacitors, electrochromic display and other applications requiring ionically conductive median are disclosed. The electrolytes of the invention contain organic cation salts, also called ionic liquids or molten salts. These improved electrolytes have useful characteristics such as high thermal stability and reduced flammability.