Showing papers on "Electrochromic devices published in 2010"

Spectral engineering in π-conjugated polymers with intramolecular donor-acceptor interactions.

Abstract: With the development of light-harvesting organic materials for solar cell applications and molecular systems with fine-tuned colors for nonemissive electrochromic devices (e.g., smart windows, e-papers), a number of technical challenges remain to be overcome. Over the years, the concept of “spectral engineering” (tailoring the complex interplay between molecular physics and the various optical phenomena occurring across the electromagnetic spectrum) has become increasingly relevant in the field of π-conjugated organic polymers. Within the spectral engineering toolbox, the “donor−acceptor” approach uses alternating electron-rich and electron-deficient moieties along a π-conjugated backbone. This approach has proved especially valuable in the synthesis of dual-band and broadly absorbing chromophores with useful photovoltaic and electrochromic properties. In this Account, we highlight and provide insight into a present controversy surrounding the origin of the dual band of absorption sometimes encountered in...

All-Organic Electrochromic Spandex

Abstract: Herein we describe the preparation and characterization of reflective-type electrochromic devices using stretchable, conductive fabric electrodes. Two fabrics were used in this study: woven stainless steel mesh and Lycra spandex impregnated with a conducting polymer (poly[3,4-ethylenedioxythiophene]-poly[styrene sulfonate], PEDOT-PSS). Electrochromic polymers were prepared on the surface of these fabric electrodes and devices were assembled. The time taken for the electrochromic polymer to switch between colored states in devices prepared with stainless steel electrodes (conductivity ca. 9,800 S/cm) was ca. 0.3 s, whereas that using PEDOT-PSS loaded Lycra (conductivity ca. 0.1 S/cm) was a few seconds. The iris effect was evaluated for each of the device architectures, showing no effect for steel mesh/steel mesh devices and a propagating front for spandex-based devices. The electrochromic spandex functioned in solution while being stretched. In addition, stenciled devices were built. Such fabric electrochr...

Fabrication of low defectivity electrochromic devices

Abstract: Prior electrochromic devices frequently suffer from high levels of defectivity. The defects may be manifest as pin holes or spots where the electrochromic transition is impaired. This is unacceptable for many applications such as electrochromic architectural glass. Improved electrochromic devices with low defectivity can be fabricated by depositing certain layered components of the electrochromic device in a single integrated deposition system. While these layers are being deposited and/or treated on a substrate, for example a glass window, the substrate never leaves a controlled ambient environment, for example a low pressure controlled atmosphere having very low levels of particles. These layers may be deposited using physical vapor deposition.

Giant plasmon resonance shift using poly(3,4-ethylenedioxythiophene) electrochemical switching.

Abstract: Herein, we report the variation of localized surface plasmon resonance (LSPR) of gold nanoparticle (NP) arrays covered by poly(3,4-ethylenedioxythiophene) (PEDOT) as a function of the electronic state of the polymer. Giant shifts and fine-tuning of the LSPR of gold NPs surrounded by PEDOT/sodium docecyl sulfate have been achieved. The color variations of plasmonic/conducting polymer (CP) devices are given not only by changes of the optical properties of the CP upon doping but also by a close synergy of the optical properties of CP and NP. Such systems can considerably extend the field of CP-based electrochromic devices.

Design, Synthesis, and Study of Main Chain Poly(N-Heterocyclic Carbene) Complexes: Applications in Electrochromic Devices

Abstract: A series of poly(N-heterocyclic carbene) complexes in which the carbene functionalities are orthogonally connected to the main chains of the respective polymers have been synthesized via oxidative electropolymerization of various bis(bithiophene)-substituted monomers with appended transition metal or main group entities (M = Ir, Au, Ag, or S). The polymers were characterized using a range of electrochemical, X-ray photoelectron spectroscopy, UV−vis spectroscopy, profilometry, and four-point probe conductivity measurements. Most of the polymers exhibited an intense absorbance wave at 700 nm under oxidative conditions which was attributable to the formation of polarons along the main chains. The iridium-containing thin film poly(8) was found to possess a significant NIR absorbance at 1100 nm in which the metal moiety effectively functioned as an electron sink. Electrochemical analyses of the polymer thin films revealed that they exhibited highly reversible electrochromic phenomena.

Electrochromic devices, assemblies incorporating electrochromic devices, and/or methods of making the same

Abstract: Certain example embodiments of this invention relate to electrochromic (EC) devices, assemblies incorporating electrochromic devices, and/or methods of making the same. More particularly, certain example embodiments of this invention relate to improved EC materials, EC device stacks, high-volume manufacturing (HVM) compatible process integration schemes, and/or high-throughput low cost deposition sources, equipment, and factories.

Gelatin in electrochromic devices

Abstract: A gelatin-based electrolyte has been developed and characterized by impedance spectroscopy and thermal analysis. These electrolytes are promising materials to be applied in electrochromic devices because gelatine is a material available in nature, it is cheap, easy to handle and to prepare. In this study the characterization of a solid-state electrochromic device based on gelatin is reported and results obtained suggest that this electrolyte is very attractive for electrochemical device applications. Gelatin-based electrolytes were successfully used in the assembly of prototype electrochromic devices (ECDs) and exhibited good optical density. The ECD display incorporating gelatine I and gelatine II samples presented in the visible region an average transmittance above 68% in the bleached state. After coloration the structure assembled with gelatine I composition presented an average transmittance in the visible wavelength region above 21% and 36% for gelatin II.

Flexible electrochromic devices, electrodes therefor, and methods of manufacture

Abstract: An electrochromic fiber or fabric is disclosed. The fiber or fabric includes a flexible, electrically conductive fiber, and a layer comprising an electrochromic material disposed on and surrounding the flexible, electrically conductive fiber. In one embodiment, the fiber or fabric is both flexible and elastic. The fibers and fabrics are of particular utility in electrochromic devices, particularly those which form or are a part of garments.

Synthesis and characterization of chemically grown electrochromic tungsten oxide

Abstract: Tungsten oxide thin films, which are cathodic coloration materials that are used in electrochromic devices, were prepared by a chemical growth method and their electrochromic properties were investigated. The thin films of WO3 were deposited onto electrically conducting substrates: fluorine doped tin oxide coated glass (FTO) with sheet resistance of about 10 Ω/cm. Transparent, uniform and strongly adherent thin film samples of WO3 were studied for their structural, morphological, optical and electrochromic properties. The XRD data confirmed the monoclinic crystal structure of WO3 thin films. The direct band gap Eg for the films was found to be 2.95 eV which is good for electrochromic device application. The electrochromism of WO3 thin film was evaluated in 0.5 M LiClO4/propylene carbonate for Li+ intercalation. Electrochromic properties of WO3 thin films were studied with the help of Cyclic Voltammetry (CV), Chronoamperometry (CA) and Chronocoulometry (CC) techniques.

Charge Transport in Redox Polyelectrolyte Multilayer Films: The Dramatic Effects of Outmost Layer and Solution Ionic Strength

Abstract: The redox switching kinetics, that is, charge transfer and transport in layer-by-layer-deposited electroactive polyelectrolyte multilayers is systematically studied with variable-scan-rate cyclic voltammetry. The experiments are performed with films finished in the redox polycation (an osmium pyridine-bipyridine derivatized polyallylamine, PAH-Os) and the polyanion (polyvinyl sulfonate, PVS), in solutions of different electrolyte concentrations. A modified diffusion model is developed to account for the experimentally observed dependence of the average peak potential with the scan rate. This model is able to describe both the redox peak potential and the current, providing information on the electron-transfer rate constants and the diffusion coefficient for the electron-hopping mechanism. While the former does not vary with the ionic strength or the nature of the outmost layer, polyanion-capped films present an electron-hopping diffusion coefficient at low ionic strength that is three orders of magnitude smaller than that for PAH-Os-capped films. The effect is offset at high ionic strength. We discuss the possible causes of the effect and the important consequences for electrochemical devices built by layer-by-layer self-assembly, such as amperometric biosensors or electrochromic devices.

Application of di-ureasil ormolytes based on lithium tetrafluoroborate in solid-state electrochromic displays

Abstract: In this study the sol–gel synthetic strategy was used to prepare organic–inorganic hybrid electrolyte systems composed of a di-urea cross-linked poly(ethylene oxide) (PEO)/siloxane (di-ureasil) matrix with a wide concentration range of lithium tetrafluoroborate (LiBF4). The assembly and preliminary characterization of a prototype solid-state electrochromic device based on a four-layer sandwich structure incorporating these hybrid electrolytes doped with controlled quantities of LiBF4 are reported. The composition of hybrid xerogels was indicated using the notation d-U(900)nLiBF4 and d-U(600)nLiBF4. In this representation the average molecular weight of the host di-ureasil framework is identified as d-U(900) or d-U(600) and the subscript n expresses the salt content in terms of the number of ether oxygen atoms per Li+ cation. The most conducting electrolyte of these hybrid systems is the d-U(900)35LiBF4 composition (1.70 × 10−4 S cm−1 at about 95 °C). The lowest decomposition temperature was observed at a composition of n = 2.5 in both the d-U(900)nLiBF4 and the d-U(600)nLiBF4 electrolyte systems (250 °C and 243 °C, respectively). Electrochromic devices assembled with d-U(900)nLiBF4 and d-U(600)nLiBF4 electrolytes with compositions of 20 ≤ n ≤ 35 presented good color contrast, a maximum optical density of 0.23 and an encouraging performance in the coloring/bleaching process. The average transmittance in the visible region of the spectrum was above 74% for all the bleached samples analyzed.

Materials and device stack for market viable electrochromic devices

Abstract: The present invention generally relates to electrochromic (EC) devices, such as used in electrochromic windows (ECWs), and their manufacture. The EC devices may comprise a transparent substrate; a first transparent conductive layer; a doped coloration layer, wherein the coloration layer dopants provide structural stability to the arrangement of atoms in the coloration layer; an electrolyte layer; a doped anode layer over said electrolyte layer, wherein the anode layer dopant provides increased electrically conductivity in the doped anode layer; and a second transparent conductive layer. A method of fabricating an electrochromic device may comprise depositing on a substrate, in sequence, a first transparent conductive layer, a doped coloration layer, an electrolyte layer, a doped anode layer, and a second transparent conductive layer, wherein at least one of the doped coloration layer, the electrolyte layer and the doped anode layer is sputter deposited using a combinatorial plasma deposition process.

Polymer electrolytes based on natural polymers

Abstract: The development of new materials that can be applied as solid electrolytes has led to the creation of modern systems of energy generation and storage. Among different poly(ethylene oxide)-based electrolytes, natural polymers, such as hydroxyethylcellulose, hydroxypropylcellulose or carboxymethylcellulose, starch and chitosan or proteins like gelatin, are also proposed. After salt or acid addition, the transparent membranes show ionic conductivity values of 10− 3 S/cm and can be applied with good stability results to electrochromic devices. The present review shows the principal results of ionic conductivity characterization of polymer electrolytes based on natural polymers with emphasis on solid state nuclear magnetic resonance (NMR) measurements.

Electrochromic device and method for producing same

Abstract: The present invention relates to electrochromic devices and methods for functionalizing cellulose-based materials, in production and post-production stages, in order to obtain solid-state electrochromic devices The invention is in the field of electrochemistry These functionalized cellulose-based materials have typical electrochromic characteristics, specifically the capacity to change the oxidation state, leading to a modification of the physical properties, shown by a color change when exposed to an electric potential difference, being this color change reversible The color remains in the absence of any electric stimulus, demonstrating a memory effect An example of an electrochromic device according to the present invention comprises a cellulose-based material soaked with a dispersion of electrochromic inorganic material nanoparticles or with a solution of electrochromic organic molecules, wherein the solution/dispersion contains at least one salt, and is finished by deposition of an electrode in each side of the cellulose-based material, wherein at least one of the electrodes is transparent

Polymer electrolytes as solid solvents and their applications

Abstract: This chapter details the preparation and mechanism of polymer electrolytes and their applications in electrochemical fields, such as lithium ion batteries, fuel cells, alkaline batteries, supercapacitors, solar cells, electrochromic devices and the like. Polymer electrolytes used in lithium ion batteries are divided into three categories: solid, gel and composites. Recent progress made in these three categories is highlighted. Moreover, in addition to the lithium ion battery, applications of polymer electrolytes in other electrochemical fields and their ion conducting performance are also briefly described.