Showing papers on "Electrochromism published in 1998"

Electrochromic polymeric solid films, manufacturing electrochromic devices using such solid films, and processes for making such solid films and devices

Abstract: The present invention relates to electrochromic polymeric solid films, manufacturing electrochromic devices using such solid films and processes for making such solid films and devices. The electrochromic polymeric solid films of the present invention exhibit beneficial properties and characteristics, especially when compared to known electrochromic media. The electrochromic polymeric solid films are transformed in situ from a low viscosity electrochromic monomer composition by exposure to electromagnetic radiation, and in so doing minimum shrinkage occurs. The electrochromic polymeric solid films of the present invention also perform well under prolonged coloration, outdoor weathering and all-climate exposure, and provide an inherent safety aspect not known to electrochromic media heretofore.

High Contrast Ratio and Fast-Switching Dual Polymer Electrochromic Devices

Abstract: A series of dual polymer electrochromic devices (ECDs) based on 12 complementary pairs of conducting polymer films have been constructed using 3,4-ethylenedioxythiophene-containing conducting polymers. Poly[3,6-bis(2-(3,4-ethylenedioxythiophene))-N-methylcarbazole] (PBEDOT-NCH3Cz), poly[3,6-bis(2-(3,4-ethylenedioxythiophene))-N-eicosylcarbazole] (PBEDOT-NC20H41Cz), and poly[4,4‘-bis(2-(3,4-ethylenedioxythiophene))biphenyl] (PBEDOT-BP) were utilized as anodically coloring polymers that electrochemically switch between an oxidized deep blue absorptive state and a transmissive (orange or yellow) reduced state. Poly(3,4-ethylenedioxythiophene) (PEDOT) and its alkyl derivatives (PEDOT-C14H29 and PEDOT-C16H33) have been used as high-contrast cathodically coloring polymers that switch between a deep blue absorptive state in the reduced form and a sky blue, highly transmissive state in the oxidized form. The dual polymer ECDs were constructed by separating complementary pairs of EC polymer films, deposited on ITO...

The Viologens: Physicochemical Properties, Synthesis and Applications of the Salts of 4,4'-Bipyridine

Abstract: Introduction and Overview. Synthesis of Viologens. Spectroscopic Properties of Viologen Species. The Structure of Bipyridilium Species. The Dication: Charge-transfer Equilibria. The Radical Cation: Dimer Formation. The Di-Reduced Bipyridilium Species: The Comproportionation Reaction. Adsorption of the Viologens. Electrochemistry and Electron-transfer Reactions. Photochemistry of the Viologens and Solar-energy Conversion. Electron Mediation, Herbicidal Activity and Toxicity. Electrochromism in Viologen-based Systems. Solid-state Conductivity and use of Viologens in Molecular Electronics. Supramolecular and Self Assembly Chemistry of the Viologens. Indexes.

Electrochromic rearview mirror incorporating a third surface metal reflector and a display/signal light

Abstract: An electrochromic mirror is disclosed for use in a vehicle rearview mirror assembly having a light source positioned behind the electrochromic mirror for selectively projecting light through the mirror. The electrochromic mirror includes front and rear spaced elements each having front and rear surfaces and being sealably bonded together in a spaced-apart relationship to define a chamber, a layer of transparent conductive material disposed on the rear surface of the front element, at least one solution-phase electrochromic material contained within the chamber, and a second electrode overlying the front surface of the rear element in contact with the electrochromic material. The second electrode includes a layer of reflective material and a coating of electrically conductive material that is at least partially transmissive and is disposed over substantially all of the front surface of the rear element. The second electrode further includes a region in front of the light source that is at least partially transmissive. The electrically conductive coating may include a single transparent layer or a plurality of partially reflective and transmissive layers, or an electrically conductive dichroic coating. The light source may be an information display, such as a compass/temperature display as used in an inside rearview mirror, or may be a signal light as used in an outside rearview mirror.

Electrochromic rearview mirror incorporating a third surface metal reflector

Abstract: An EC variable reflectance mirror (110) for a vehicle includes a reflector/electrode (120) on the third surface (114a) of the mirror. This reflector/electrode forms an integral electrode in contact with the electrochromic media, and may be a single layer of a highly reflective material or may comprise a series of coatings.

Efficient lateral electron transport inside a monolayer of aromatic amines anchored on nanocrystalline metal oxide films

Abstract: A monolayer of a phosphonated triarylamine adsorbed on nanocrystalline TiO2, ZrO2, or Al2O3 film deposited on conducting glass displays reversible electrochemical and electrochromic behavior although the redox potential of the electroactive molecules (0.80 V vs NHE) lies in the forbidden band of the semiconducting or insulating oxides. The mechanism of charge transport was found to involve hole injection from the conducting support followed by lateral electron hopping within the monolayer. The apparent diffusion coefficient ranged from 2.8 × 10-12 m2 s-1 in the neat 1-ethyl-2-methylimidazolium bis(trifluoromethylsulfonyl)imide (EtMeIm+Tf2N-) to 1.1 × 10-11 m2 s-1 in acetonitrile + 2 M EtMeIm+Tf2N-. A percolation threshold for electronic conductivity was found at a surface coverage corresponding to 50% of a full monolayer.

Electrochromic mirror with two thin glass elements and a gelled electrochromic medium

Abstract: An improved electrochromic rearview mirror for motor vehicles, the mirror incorporating thin front and rear spaced glass elements having a thickness ranging from about 0.5 to about 1.5. A layer of transparent conductive material is placed onto the mirror's second surface, and either another layer of transparent conductive material or a combined reflector/electrode is placed onto the mirror's third surface. A chamber, defined by the layers on the interior surfaces of the front and rear glass elements and a peripheral sealing member, contains a free-standing gel comprising a solvent and a crosslinked polymer matrix. The chamber further contains at least one electrochromic material in solution with the solvent and interspersed in the crosslinked polymer matrix. The gel cooperatively interacts with the thin glass elements to form a thick, strong unitary member which is resistant to flexing, warping, bowing and/or shattering and further allows the mirror to exhibit reduced vibrational distortion and double imaging.

Electroactivity Enhancement by Redox Matching in Cobalt Salen–Based Conducting Polymers

Abstract: The preparation of polymer-modified electrodes that function as electrocatalysts, chemical sensors, and electrochromic displays remains an active field of research. We are currently engaged in the design of new conducting polymer architectures containing transition metals in welldefined coordination environments. Our interest in these materials is motivated by the wealth of desirable characteristics endowed by transition metals for the development of sensory materials that should be responsive to anions, Lewis bases, and small molecules (CO, O2, NO, etc.). [3,4]

Electrochromic mirrors having a signal light

Abstract: An improved electrochromic rearview mirror assembly for motor vehicles is disclosed that includes a signal light mounted behind the electrochromic mirror. The electrochromic mirror has a signal light area formed in its reflective coating by removing a portion of the reflective coating and aligning the signal light with this signal light area. The portion removed is laser ablated to leave lines devoid of reflective material separated by lines of the reflective material. The signal light area may be formed in the reflective coating of the electrochromic mirror regardless of whether the reflective coating is applied to the rear or front surface of the rear element of the electrochromic mirror. If the reflective coating is applied to the front surface of the rear element (i.e., the third surface), the reflective material used is also electrically conductive so as to function as one of the electrodes for the electrochromic mirror. In this case, the remaining lines of reflective material in the signal light area are in electrical contact with the remaining reflective and conductive layer on the third surface. The reflective layer forms an integral electrode in contact with the electrochromic media, and may be a single layer of a highly reflective material or may comprise a series of coatings where the outer coating is a highly reflecting material.

Characterization and Electrochromic Properties of Ultrathin Films Self-Assembled from Poly(diallyldimethylammonium) Chloride and Sodium Decatungstate

Abstract: Poly(diallyldimethylammonium) chloride (P) and sodium decatungstate (W) were layer-by-layer self-assembled onto quartz, mica, and ITO-electrode substrates (S). The self-assembled films, S-(P/W)n, were characterized by absorption spectrophotometry, reflectivity, cyclic voltammetry and scanning force microscopy (AFM). The electrochemical properties of the S-(P/W)n films were found to differ from those in which the polyelectrolyte remained at the outermost layer, i.e., S-(P/W)n/P. Photoelectrochemical measurements provided evidence for the electrochromic and photoelectrochromic behavior of these films.

Enhancement of Photochromism and Electrochromism in MoO3/Au and MoO3/Pt Thin Films

Abstract: Freshly vacuum-evaporated, neat amorphous MoO3 thin films exhibit only UV photochromism. Visible-light photochromism is induced in these films when they are cathodically polarized for a short duration in a nonaqueous electrolyte. The efficiencies of the UV and visible-light photochromism of the MoO3 thin films increase at least 2-fold when they are coated with a thin layer (∼20-nm thickness) of Au or Pt. The enhancement in photochromism is attributed to the presence of a large Schottky barrier at the metal−semiconductor interface, which facilitates electron capture by Au or Pt. The electron capture by the metal produces a longer electron−hole separation lifetime, thereby enhancing the photochromic process. For the electrochromic process, the coloring and bleaching current densities for the MoO3/Au thin-film electrode are about 1.5 and 2.0 times larger than the respective current densities for the MoO3 thin-film electrode. The enhancement in electrochromism is ascribed to the electrocatalytic effect of the...

Microstructures of Electrochromic MoO3 Thin Films Colored by Injection of Different Cations

Abstract: Raman microscopy was used to investigate microstructural properties of amorphous MoO3 thin films that had been subjected to a photochromic (PC) or electrochromic (EC) process. The Raman spectra cha...

Electrochromic window with high reflectivity modulation

Abstract: A multi-layered, active, thin film, solid-state electrochromic device having a high reflectivity in the near infrared in a colored state, a high reflectivity and transmissivity modulation when switching between colored and bleached states, a low absorptivity in the near infrared, and fast switching times, and methods for its manufacture and switching are provided. In one embodiment, a multi-layered device comprising a first indium tin oxide transparent electronic conductor, a transparent ion blocking layer, a tungsten oxide electrochromic anode, a lithium ion conducting-electrically resistive electrolyte, a complimentary lithium mixed metal oxide electrochromic cathode, a transparent ohmic contact layer, a second indium oxide transparent electronic conductor, and a silicon nitride encapsulant is provided. Through elimination of optional intermediate layers, simplified device designs are provided as alternative embodiments. Typical colored-state reflectivity of the multi-layered device is greater than 50% in the near infrared, bleached-state reflectivity is less than 40% in the visible, bleached-state transmissivity is greater than 60% in the near infrared and greater than 40% in the visible, and spectral absorbance is less than 50% in the range from 0.65-2.5 μm.

Reflectance control of an electrochromic element using a variable duty cycle drive

Abstract: An electronic circuit for an electrochromic element. In order to improve the response time of the electrochromic element and reduce the cost and complexity, a modulated signal, such as a pulse width modulated (PWM) signal is coupled to the electrochromic element without signal averaging. In order to compensate for the compressed operating range of the reflectance characteristic under such conditions, the electronic circuit in accordance with the present invention utilizes active loading or alternatively voltage feedback of the electrochromic element to provide a reflectance response characteristic with an uncompressed linear operating range similar to a reflectance characteristic for an electrochromic element with a DC drive circuit.

XRD and XPS characterization of electrochromic nickel oxide thin films prepared by electrolysis–chemical deposition

Abstract: Electrochromic (EC) behaviours of nickel oxide (NiOx) thin films, grown by chemical process in a nickel ammine complex solution [Ni(NH3)x2+] after electrolysis of this solution (EL–C method), were investigated using various alkaline electrolyte solutions; potassium borate buffer (pH 12), KOH (pH 12.9), (CH3)4NOH and (C2H5)4NOH. The fully oxidized films in all adopted electrolytes commonly showed broadened UV–VIS spectra in the visible and near IR region. However, voltammetry studies associated with photoabsorption of the films revealed an apparent difference in the EC dynamics among the electrolytes caused by the variation of cation sizes and electrolyte solution pH. Characterization of as-prepared, oxidized and reduced films in the electrolytes by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were performed to explain the mechanism of the films based on the conversion between layered α-Ni(OH)2 and γ2-2NiO2·NiOOH. A model according to the extraction/insertion of cations or water molecules from/into the interlayer was proposed.

The Dynamics of Mobile Ions in Ionically Conducting Glasses and Other Materials

Abstract: The range of applications for ionically conducting materials in technology is very broad and includes batteries; fuel cells; sensors; electrochromic displays; catalysts, oxygen, and hydrogen pumps; and bionics. In most of these applications, the mobility of the ions is a determining factor for optimum performance. Examples are liquid-electrolyte and plastic Li+ ion batteries for portable electronics, solid oxide fuel cells such as the oxygen ion-conducting stabilized zirconia electrolyte for energy conversion, and exchange of different ions in oxide glasses for the fabrication of micro-optic lenses. Therefore research on the dynamics of ionic transport that clarifies the mechanisms limiting the mobility of the ions is useful. These dynamic processes are also fascinating from a basic research point of view and qualitatively follow general patterns independent of the chemical and physical structures of the materials, suggesting that some fundamental physical mechanism is at work. On a quantitative level, the ionic-transport properties depend on the structures of the materials seemingly in well-defined patterns, which can be used to advantage in choosing materials for specific applications.