Showing papers on "Electrochromism published in 2006"
TL;DR: In this review, the general field of electro Chromism is introduced, with coverage of the types, applications, and chemical classes of electrochromic materials and the experimental methods that are used in their study.
932 citations
TL;DR: In this paper, the authors proposed two important criteria for selecting an EC material: the time constant of the ion-intercalation reaction, which is limited both by the diffusion coefficient and by the length of the diffusion path, and the coloration efficiency, the change in optical density (OD) per unit inserted charge, that is, CE= D(OD)/DQ.
Abstract: Electrochromic (EC) materials change their optical properties (darken/lighten) in the presence of a small electric potential difference, and are suitable for application in energy-efficient windows, antiglare automobile rear-view mirrors, sunroofs, displays, and hydrogen sensors. [1–4] The operation of conventional EC devices depends on the reversible electrochemical double injection of positive ions (H + ,L i + ,N a + ) and electrons into the host lattice of multivalent transition metal oxide materials, [5–10] with positive-ion insertion required to satisfy charge neutrality. However, diffusion of positive ions into the oxide layer is often slow, taking minutes to complete. Since the chemical diffusion coefficient of protons (DH+ )i s an order of magnitude larger than that of lithium ions (DLi+), EC systems based on proton electrolytes (e.g., aqueous H2SO4) are mandatory for display applications and preferred for other applications. Unfortunately, proton insertion currently results in rapid degradation of EC films. There are two important criteria for selecting an EC material. The first is the time constant of the ion-intercalation reaction, which is limited both by the diffusion coefficient and by the length of the diffusion path. While the former depends on the chemical structure and crystal structure of the metal oxide, the latter is determined by the material’s microstructure. [11] In the case of a nanoparticle, the smallest dimension is represented by the diffusion path length. Thus, designing a nanostructure with a small radius, while maintaining the proper crystal structure, is key to obtaining a material with fast insertion kinetics, enhanced durability, and superior performance. The second important criterion is coloration efficiency (CE), the change in optical density (OD) per unit inserted charge (Q), that is, CE= D(OD)/DQ. [12] A high CE provides
528 citations
TL;DR: A family of soluble narrow band gap donor-acceptor conjugated polymers based on dioxythiophenes and cyanovinylenes is reported, which show three accessible color states changing from an absorptive blue or purple in the neutral state to a transmissive sky-blue or gray in the oxidized and reduced forms.
Abstract: A family of soluble narrow band gap donor-acceptor conjugated polymers based on dioxythiophenes and cyanovinylenes is reported. The polymers were synthesized using Knoevenagel polycondensation or Yamamoto coupling polymerizations to yield polymers with molecular weights on the order of 10 000-20 000 g/mol, which possess solubility in common organic solvents. Thin film optical measurements revealed narrow band gaps of 1.5-1.8 eV, which gives the polymers a strong overlap of the solar spectrum. The energetic positions of the band edges were determined by cyclic voltammetry and differential pulse voltammetry and demonstrate that the polymers are both air stable and show a strong propensity for photoinduced charge transfer to fullerene acceptors. Such measurements also suggest that the polymers can be both p- and n-type doped, which is supported by spectroelectrochemical results. These polymers have been investigated as electron donors in photovoltaic devices in combination with PCBM ([6,6]-phenyl C(61)-butyric acid methyl ester) as an electron acceptor based on the near ideal band structures designed into the polymers. Efficiencies as high as 0.2% (AM1.5) with short circuit current densities as high as 1.2-1.3 mA/cm(2) have been observed in polymer/PCBM (1:4 by weight) devices and external quantum efficiencies of more than 10% have been observed at wavelengths longer than 600 nm. The electrochromic properties of the narrow band gap polymers are also of interest as the polymers show three accessible color states changing from an absorptive blue or purple in the neutral state to a transmissive sky-blue or gray in the oxidized and reduced forms. The wide electrochemical range of electrochromic activity coupled with the strong observed changes in transmissivity between oxidation states makes these materials potentially interesting for application to electrochromic displays.
387 citations
TL;DR: Electrochromic materials have been around for more than 30 years and have found some applications in niche areas, but now, thanks to new electro chromic materials and manufacturing procedures, electrochromism may become a household word.
Abstract: Electrochromic materials have been around for more than 30 years and have found some applications in niche areas. Now, thanks to new electrochromic materials and manufacturing procedures, electrochromism may become a household word.
292 citations
TL;DR: In this article, anodic TiO 2 nanotube layers were fabricated by anodization of titanium in 1.5% HF electrolyte at 20V, this results in nanotubular layers with a thickness of 1.1μm with individual tube diameter of 100 ± 10nm and a tube wall thickness of 10± 2nm.
205 citations
TL;DR: In this article, a survey and new data on optical absorption in Tungsten Oxide and Nickel Oxide Films is presented, along with a detailed discussion of the optical properties of these materials.
188 citations
TL;DR: The influence of mesoporosity and crystallinity on electrochemical/electrochromic characteristics was addressed by monitoring electrochemical features and the absorption changes during Li insertion/extraction (repetitive potentiostatic cycling).
Abstract: WO3 thin layers with nanometer-scale periodicity were prepared by evaporation-induced self-assembly (EISA) using a novel amphiphilic block-copolymer template (poly(ethylene-co-butylene)-block-poly(ethylene oxide)). The evolution of the mesoporous ordered network and the crystallinity of the framework were monitored by 2D-SAXS, WAXS, SEM, XPS, and porosimetry. By annealing the films, the pore-wall crystallinity is adjusted between fully amorphous and highly crystalline without mesostructural degradation. Thus, the crystalline-film framework is composed of phase-pure monoclinic WO3 nanoparticles (12-14 nm in size). Furthermore, heat treatment transforms the originally spherical mesopores into ellipsoids, resulting in a unidirectionally shrunken, but still well-defined and fully accessible bcc mesopore architecture. The influence of mesoporosity and crystallinity on electrochemical/electrochromic characteristics was addressed by monitoring electrochemical features and the absorption changes during Li insertion/extraction (repetitive potentiostatic cycling). Both the amorphous and crystalline mesoporous films possess electrochromic response times on the order of only seconds, which are attributable to the facilitated insertion of guest ions due to shortening of the diffusion path lengths. Also, the insertion/extraction reversibility of crystalline WO3 layers with 3D mesoporosity is improved compared to amorphous ones and reaches values close to 100%.
171 citations
TL;DR: The poly(3,4-dioxypyrrole) (PXDOP) family of conducting and electroactive polymers has now been developed to the point that multiple synthetic routes allow many functionalized polymers with controllable optoelectronic and redox properties.
Abstract: The poly(3,4-dioxypyrrole) (PXDOP) family of conducting and electroactive polymers has now been developed to the point that multiple synthetic routes allow many functionalized polymers with controllable optoelectronic and redox properties. These properties, which include high conductivity, multicolor cathodic and anodic electrochromism, and rapid redox switching, allow these materials to be used in a variety of applications that potentially include conducting coatings, electrochromic windows and displays, chemical sensors, bioactive materials, and mechanical actuators. Surprisingly, the scientific literature published on the PXDOP derivatives has been isolated and sparse compared to that of other conducting polymers. This report will highlight the synthesis and materials properties of PXDOPs and show how these powerful materials fit into the frontier of conducting polymers research.
145 citations
TL;DR: In this paper, two conducting polymers, polyaniline (PANI) and poly(3,4-ethylenedioxythiophene) (PEDOT), were used to construct an electrochromic device (ECD).
140 citations
TL;DR: In this paper, the Suzuki−Miyaura cross-coupling reaction between 4butyl-N,N-bis((4,4,5,5-tetramethyl-1,3,2-dioxaborolan-4-phenyl)aniline) and several aryl dibromide molecules was used to modulate the electronic properties of the resulting copolymers.
Abstract: We report the preparation and characterization of new electrochromic polymers containing a 4-butyltriphenylamine (BuTPA) unit on the main chain. All polymers were obtained through the Suzuki−Miyaura cross-coupling reaction between 4-butyl-N,N-bis((4,4,5,5-tetramethyl-1,3,2-dioxaborolan-4-phenyl)aniline) and several aryl dibromide molecules to modulate the electronic properties of the resulting copolymers. 2,5-Dibromothiophene, 2,5-dibromo(3,4-ethylenedioxythiophene), 3,6-dibromo-N-octylcarbazole, bis(6-bromo-N-octylcarbazol-3-yl), and 2,7-dibromo-3,6-dimethoxy-9,9-dihexylfluorene were used as comonomers and led to five new copolymers, PT(BuTPA), PE(BuTPA), PC(BuTPA), PCC(BuTPA), and PF(BuTPA). These polymers are readily soluble in many common organic solvents, which make them suitable for spray-coating film deposition. Electrochromic cells with the following configuration were assembled: ITO-coated glass or plastic/electrochromic polymer/gel electrolyte/ITO-coated glass or plastic or conducting textile. ...
137 citations
TL;DR: In this paper, the morphological and structural evolution of spin and dip coated films as a function of annealing temperature (250 and 500°C) has been examined and compared by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD).
TL;DR: In this article, the authors worked in a private office with switchable electrochromic windows, manually operated Venetian blinds, and dimmable fluorescent lights, and found that the electrics reduced the incidence of glare compared to working under a fixed transmittance (60%) condition.
TL;DR: In this paper, a new carbazole-derived triphenylamine-containing aromatic dicarboxylic acid monomer was successfully synthesized by the cesium-fluoride-mediated condensation of N-(4-aminophenyl)carbazole with 4fluorobenzonitrile, followed by alkaline hydrolysis of the dinitrile intermediate.
Abstract: A new carbazole-derived triphenylamine-containing aromatic dicarboxylic acid monomer, 4,4‘-dicarboxy-4‘ ‘-N-carbazolyltriphenylamine, with blue light (460 nm) fluorescence quantum yield of 40% was successfully synthesized by the cesium-fluoride-mediated condensation of N-(4-aminophenyl)carbazole with 4-fluorobenzonitrile, followed by alkaline hydrolysis of the dinitrile intermediate. A series of novel poly(amine-amide)s with pendent N-phenylcarbazole units having inherent viscosities of 0.36−0.61 dL/g were prepared from the newly synthesized dicarboxylic acid monomer and various aromatic diamines by direct phosphorylation polycondensation. The obtained polymers were amorphous and could afford flexible, transparent, and tough films with good mechanical properties. They had useful levels of thermal stability associated with relatively high glass-transition temperatures (269−322 °C). These polymers exhibited strong UV−vis absorption maxima at 340−361 nm, and their photoluminescence showed emission peaks arou...
TL;DR: Vanadium oxide nanowires were prepared successfully by thermal evaporation onto ITO-coated glass at a pressure of 8 × 1 0 - 4 Torr and 650°C from vanadium oxide powders (V 2 O 5 99.95%) as discussed by the authors.
TL;DR: In this article, a new synthesis methodology was developed for the chemical synthesis of the hybrid PAni/PMo12 and their application as electrochemical supercapacitors, which achieved capacitance values as high as 168 F/g for the hybrid and about 130 F /g for PEDOT/Po12.
Journal Article•
TL;DR: In this paper, the application of TG analysis to optimisation of the electrochromic response of sol-gel prepared Ni oxide thin films is presented, and the results of thermal analysis of thin films deposited on a substrate are summarized.
Abstract: An electrochromic material changes its optical properties in the visible part of the spectrum under a certain applied potential. The change is reversible and the material returns to its original state under the opposite electric field. Recently, electrochromism has been applied in electrochromic devices, where in a battery-like assembly the throughput of solar light is controlled by the voltage and is usually termed a smart window. In the first part of this article a brief theoretical introduction to electrochromism and the functioning of smart windows is given. Since in the last decade nickel oxide has been extensively studied as an ion-storage material in electrochromic devices, some properties of nickel oxide are explained in the following part. The electrochromic response (reversibility during potential switching and the degree of coloration) of a nickel oxide thin film, used in a electrochromic device, strongly depends on the degree of heat treatment. Thermal analysis of thin films can give valuable information about a suitable temperature and the duration of heat-treatment when thin films are prepared by chemical methods of deposition. Since thermal analysis of thin films deposited on a substrate is not a common analytical technique, basic strategies are also summarized in the article. After this theoretical introduction, the application of TG analysis to optimisation of the electrochromic response of sol-gel prepared Ni oxide thin films is presented. The electrochromic properties of thin films, thermally treated to different degrees, were tested using spectroelectrochemical methods. Additional techniques (IR, TEM, AFM and EXAFS) were indispensable in following structural and morphological changes during the heat treatment.
TL;DR: In this article, N-functionalized dithieno[3,2-b:2,2,3,d]pyrroles via both chemical oxidation and electropolymerization are presented.
Abstract: Oxidative polymerization studies of N-functionalized dithieno[3,2-b:2‘,3‘-d]pyrroles (where substituent = hexyl, octyl, decyl, octadecyl, tert-butyl, 2-ethylhexyl, or p-hexylphenyl) via both chemical oxidation and electropolymerization are presented. While electropolymerized samples are insoluble, it is possible to isolate soluble materials via chemical oxidation methods. Solution and solid-state characterization of the resulting polymeric materials is described, including photophysical and electrochemical studies, and these properties are compared to related polythiophene materials. In addition to reduced band gaps (∼1.7 eV), these materials exhibit good red emission with solution quantum efficiencies up to 34%.
Patent•
31 Mar 2006TL;DR: In this article, the authors present polymers and copolymers comprising repeating units of thieno[3,4-b]thiophene, which can be cast by conventional methods to provide uniform, thin films.
Abstract: This invention presents polymers and copolymers comprising repeating units of thieno[3,4-b]thiophene. Water-borne dispersions of such polymers and copolymers can be cast by conventional methods to provide uniform, thin films which possess utility in numerous electroactive applications including electrochromic displays, optically transparent electrodes and antistatic coatings. The compositions of this invention can be doped with conventional p-dopants or n-dopants. The invention also presents an aqueous process for preparing such compositions of matter.
TL;DR: In this article, the most relevant devices currently used in order to achieve electrically stimulated generations of colours from electroactive polymers, either as coloured light emissions from the material or as modifications of its intrinsic colour properties are reviewed.
Abstract: This paper focuses on the most relevant devices currently used in order to achieve electrically stimulated generations of colours from electroactive polymers, either as coloured light emissions from the material or as modifications of its intrinsic colour properties. For this purpose, most relevant materials, fundamental principles of operations, latest developments and current applications of organic-based electrochromic, electroluminescent and lasing devices are reviewed here. The very promising performances resulting from the analysis of state-of-the-art products, and in particular of those which are currently approaching commercial applications, suggest likely roles played by such devices for niche applications in the very near future.
Patent•
06 Feb 2006TL;DR: In this article, an electrochromic mirror is used in a vehicle rearview mirror assembly with a light source positioned behind the mirror for selectively projecting light through the mirror, where the reflective and transmissive materials are disposed over the front surface of the rear element.
Abstract: The inventive electrochromic mirror may be used 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, an electrochromic material is contained within the chamber, and a second electrode overlies the front surface of the rear element in contact with the electrochromic material. The second electrode includes a layer of reflective material and a partially transmissive coating of 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.
TL;DR: In this article, a new carbazole-derived triphenylamine-containing aromatic diamine monomer was successfully synthesized by the caesium fluoride-mediated condensation of N-(4-aminophenyl)carbazole with 4-fluoronitrobenzene, followed by palladium-catalyzed hydrazine reduction.
Abstract: A new carbazole-derived, triphenylamine-containing aromatic diamine monomer, 4,4′-diamino-4″-N-carbazolyltriphenylamine, was successfully synthesized by the caesium fluoride-mediated condensation of N-(4-aminophenyl)carbazole with 4-fluoronitrobenzene, followed by palladium-catalyzed hydrazine reduction. A series of novel poly(amine-imide)s 6a–6g with pendent N-phenylcarbazole units having inherent viscosities of 0.17–0.56 dL g−1 were prepared from the newly synthesized diamine monomer and seven commercially available tetracarboxylic dianhydrides via a conventional two-step procedure that included a ring-opening polyaddition to give polyamic acids, followed by chemical or thermal cyclodehydration. The polymers of the series were amorphous and most of them could afford flexible, transparent, and tough films with good mechanical properties. All the poly(amine-imide)s had useful levels of thermal stability associated with high glass-transition temperatures (303–371 °C), 10% weight-loss temperatures in excess of 543 °C, and char yields at 800 °C in nitrogen higher than 60%. The poly(amine-imide)s 6e–6g exhibited a UV-vis absorption maximum at around 300 nm in NMP solution. The poly(amine-imide) 6g derived from an aliphatic dianhydride was optically transparent in the visible region and fluoresced violet–blue at 403 nm in NMP with 4.54% quantum yield higher than the wholly aromatic 6e and 6f. The hole-transporting and electrochromic properties were examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the poly(amine-imide) films on an indium-tin oxide (ITO)-coated glass substrate exhibited a reversible oxidation wave at 1.05 V and an additional irreversible oxidation wave at 1.39 V versus Ag/AgCl in acetonitrile solution. The polymer films revealed excellent stability of electrochromic characteristics, with a color change from neutral pale yellowish to green doped form at applied potentials ranging from 0.00 to 1.15 V.
TL;DR: In this paper, a simple method was developed to fabricate tungsten oxide (WO3−x) nanowires based electrochromic devices, which can be grown on a large scale directly onto an ITO-coated glass.
TL;DR: A potential driven self-assembly of sodium dodecyl sulfate/tungsten oxide aggregates at the electrolyte-electrode interface followed by template extraction and annealing yielded mesoporous thin films of electrochromic tungstenoxide (WO(3).
Abstract: A potential driven self-assembly of sodium dodecyl sulfate/tungsten oxide aggregates at the electrolyte–electrode interface followed by template extraction and annealing yielded mesoporous thin films of electrochromic tungsten oxide (WO3). Electron microscopy images revealed that the films are characterized by a hitherto unreported hybrid structure comprising nanoparticles and nanorods with a tetragonal crystalline phase of WO3 with the measured lattice parameters: a = 0.53 nm and c = 0.37 nm. In addition to pentagonal voids characteristic of the tetragonal WO3 phase at the lattice scale, open channels and pores of 5–10 nm in diameter lie between the nanoparticles, which cumulatively promote rapid charge transport through the film. This resulted in colouration efficiency (ηmax~90 cm2 C−1 at λ = 900 nm) and switching kinetics (colouration time = 3 s and bleaching time = 2 s for a 50% change in transmittance) higher and faster than previously reported values for mesoporous WO3 films. Repetitive cycling between the clear and blue states has no deleterious effect on the electrochromic performance of the film, which is suggestive of its potential as a cathode in practical electrochromic windows.
TL;DR: In this article, a new soluble polythiophene derivative was synthesized by both chemical and electrochemical oxidative polymerization of 1-4-nitrophenyl-2,5-di(2-thienyl)-1 H -pyrrole (SNSNO 2 ).
TL;DR: In this paper, the synthesis and characterization of a novel donor-acceptor (D−A) bichromophore system composed of two D−A segments linking through a spiro center are reported.
Abstract: The synthesis and photophysical, electrochemical, and spectroelectrochemical characterization of a novel donor−acceptor (D−A) bichromophore system composed of two D−A segments linking through a spiro center are reported. The electron-donating (D) moieties are triphenylamine (TPA) groups, whereas the electron-withdrawing (A) moieties are cyano groups. The particular “spiro” configuration that perpendicularly bonds the D−A chromophores by a tetrahedral carbon, impedes orbital interactions between the branches. Thus, the two TPA substituents act independently, rendering an efficient electropolymerization process feasible. The polymer film obtained showed reversible electrochemical oxidation accompanied by strong color changes with high coloration efficiency and contrast ratio, which can be switched by potential modulation. The remarkable electrochromic behavior of the film is clearly interpreted on the basis of spectroelectrochemical studies. A plausible polymerization mechanism involved with the TPA dimeriz...
TL;DR: In this article, the annealing-induced microstructural evolution for amorphous tungsten oxide films is shown to show quasi-reversible structural changes, as ascertained by X-ray diffraction and Fourier transform infrared spectral data, and a high optical modulation of 72% (gimel=650nm) and a coloration efficiency maximum of 132 cm(2) C-1 at 800 nm under a lithium intercalation level of x = 0.20.
Abstract: As-deposited sol-gel derived amorphous tungsten oxide films transform into nanostructured films with an interconnected framework of grains and pores and a dominant triclinic crystalline phase upon annealing at 250 degrees C. Transmission electron microscopy and scanning electron microscopy images clearly reveal the annealing-induced microstructural evolution for the film. Subsequent to lithium intercalation, the film annealed at 250 degrees C shows quasi-reversible structural changes, as ascertained by X-ray diffraction and Fourier transform infrared spectral data. Dynamic transmission modulation for film revealed a high optical modulation of 72% (gimel=650nm) and a coloration efficiency maximum of 132 cm(2) C-1 at 800 nm under a lithium intercalation level of x = 0.20. X-ray photoelectron spectroscopy of the W 4f core levels demonstrated a progressive increase in the W5+ content at the expense of W6+ proportion as the insertion coefficient was raised from 0 to 0.25, with 0.20 as the threshold value above which the W5+ content exceeds the W6+ proportion. A new W4+ state also appears which acts to lower the coloration efficiency for x >= 0.22. The presence of charged oxygen interstitials in the vicinity of electrochemically active tungsten sites is also responsible for the coloration efficiency decline at high ion insertion levels.
TL;DR: In this article, the effect of tungsten addition on the electrochromic properties of NiO thin films was investigated, and an increase in cyclability for NiO (5% t WO 3 ) electrode, cycled in KOH 1/M electrolyte, was associated with a limited dissolution of the oxidized phases with tengsten addition, which is correlated with the existence of an α (II) hydroxide phase.
TL;DR: In this paper, three types of memory devices based on electrochromic polymers are prepared that use variations in optical density in dual-type EC devices, and data is stored by using: (1) high contrast ratio between the oxidized and neutral states of the polymer, (2) different intensities of absorptions at different oxidation levels of polymer and (3) a mixture of any two additive primary colours (red, green and blue) in various oxidation levels.
Abstract: Three types of memory devices based on electrochromic polymers are prepared that use variations in optical density in dual type EC devices. In these devices, conducting electrochromic polymers act as the active layer and data is stored by using: (1) high contrast ratio between the oxidized and neutral states of the polymer, (2) different intensities of absorptions at different oxidation levels of polymer and (3) a mixture of any two additive primary colours (red, green and blue) in various oxidation levels.
TL;DR: In this paper, a semi-empirical model of the steady-state behavior of electrochemical transistors is proposed and compared with experimental observations of potential and electrochromic measurements within a device.
Abstract: Electrochemical transistors based on conjugated polymers are proposed as a path to printed electronics on paper. The electrochemical doping/dedoping of conjugated polymers clearly plays a role in the current vs potential (I-V) characteristics of these devices, however, the mechanism of current saturation (often referred to as pinch-off) is not clearly understood, and the relationship between electrochemical devices and field-effect transistors is unclear. This paper offers a semiempirical model of the steady-state behavior of electrochemical transistors and compares this model with experimental observations of potential and electrochromic measurements within a device to illustrate the science behind the functionality observed. ©2006 The Electrochemical Society
TL;DR: In this paper, a new organic-inorganic complementary ECD was assembled in combination with a PMMA-based gel polymer electrolyte, which exhibited deep blue-violet when applying −2.1 V and became light blue when applying 0.6 V. The cell retained 55% of its maximum transmittance window after 50,640 repeated cycles.