Electrochromic displays based on WO3

Faughnan, Brian W.; Crandall, Richard S.

doi:10.1007/3540098682_12

Cited by 102 publications

(58 citation statements)

References 34 publications

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“…As further studies are performed, we expect to gain a better understanding of the nature of electrochromism and its relationship to structural and chemical changes in nickel hydroxide. 400 (11) ," ~ Ni(OH 2 ) 405( 0')…”

Section: Fourier-transform Infrared Spectroscopymentioning

confidence: 99%

“…Ni(OH 2 ) -OH group bend 483sh,568w 500-550 530 540s 525-549 470(0'), 513 (11) 525s 540-550s 530 (11) Codes: Phases (0'), (11), (I), nickel sulfate precipitation: n.s.p., sintered powder: s.p., powder: p weak: w, broad: b, strong: s, shoulder: sh, medium: m.…”

Section: (11)mentioning

confidence: 99%

“…As a result of this injection/ejection, color centers are formed in the material, producing optical absorption principally in the visible wavelength region, although near-infrared (NIR) absorption is possible. 2 These changes in optical density, between the colored and bleached states, represent both chemical and structural changes in the material.…”

Section: Introductionmentioning

confidence: 99%

“…These layers consist of a transparent conductive coated substrate, an electrochromic material (working electrode), a polymeric iOil conductor (which can also serve as a lamination material), an electrochromic material (counter electrode), and another transparent conductive substrate. By applying a low potential (1)(2)(3) V) between the working and counter electrodes, protons/ions are shuttled from the ion conductor into the electrochromic materials causing the desired effect of coloration or bleaching. For in-situ spectroscopic studies, the polymeric ion conductor was replaced by a liquid electrolyte.…”

Section: Introductionmentioning

confidence: 99%

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In-situ spectroscopic studies of electrochromic hydrated nickel oxide films

Lampert

1989

Solar Energy Materials

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In this investigation, in-situ spectroscopic studies of anodically deposited electrochromic hydrated nickel oxide electrodes were performed by visible/near-infrared spectroscopy and Fourier-Transform Infrared (FTIR) spectroscopy. All measurements were taken while the nickel oxide thin films were switching between the bleached and colored states, where the electrodes were not removed from the electrochemical cell. Optical transmittance measurements of the nickel oxide film relative to tin oxide coated glass varied during coloring from the integrated solar spectral transmittance, T.=1010/0-54%, and average near-infrared transmittance, T ni , = 1010/0-83%. The photopic transmission was Tp = 101 -31%. Transmittance" measurements versus time were also performed at selected wavelength values, ranging from 315 to llOO nm. Also diffe"rent scan rates (10-100 mV/s) were investigated at each of these wavelengths, where optimum switching rates could be determined. All changes in optical density were achieved by continuously cycling between a potential range ot.-5oo to +800 mY. Coloration occurs at a faster rate than bleaching of the films at every switching rate selected. Also, maximum and minimum transmission measurements at 420 nm do not to correspond to the cathodic and anodic peak current densities. Instead these transmission measurements correspond to the regions past the peak current densities. From these optical experiments, plots of transmission (%) versus voltage (mV) and transmission (%) versus total extracted charge (mC) were obtained. For FTIR spectroscopic experiments, chemical identification of the 10-20 nm thick films showed that the films exhibit different bonding environments for both the colored and bleached states. There exist surface hydroxyl groups associated with nickel oxide in the region of 3600-3800 cm-1 wave numbers. Fundamental water vibrations are also found at 3200-3500 cm-1 and at 1600-1700 cm-1 wave numbers. The nickel oxygen vibration region is at 400-525 cm-1 for both states. The coinparison of bleached and colored states exhibits distinctive molecular vibrational states, which correspond to Ni(OHh and NiOOH respectively.

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Section: Fourier-transform Infrared Spectroscopymentioning

confidence: 99%

Section: (11)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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In-situ spectroscopic studies of electrochromic hydrated nickel oxide films

Lampert

1989

Solar Energy Materials

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“…The two limiting mechanisms for charge compensation during oxidation of the hybrid material are departure of the cations and electrons from the film and arrival of the anions from the electrolyte. In tungsten oxide, during oxidation the back emf acts in the same direction as applied potential, 36 and therefore a larger driving force is available for charge transfer at the hybrid film/electrolyte interface in comparison to the pure polymer film for the same value of applied bias. Further, in the hybrid film, electron movement occurs through tungsten oxide tethered to the SnO 2 :F coating; the barrier to electron transport is nonresistive.…”

Section: Journal Of the Electrochemical Society 155 ͑11͒ D703-d710 ͑mentioning

confidence: 99%

Nanostructured Tungsten Oxide-Poly(3,4-ethylenedioxythiophene):Poly(styrenesulfonate) Hybrid Films: Synthesis, Electrochromic Response, and Durability Characteristics

Deepa

Srivastava

Sood

et al. 2008

J. Electrochem. Soc.

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Nanostructured hybrid thin films of the system tungsten oxide-poly͑3,4-ethylenedioxythiophene͒:poly͑styrenesulfonate͒ ͑WO 3 -PEDOT:PSS͒ were synthesized by first forming a tungsten-oxide layer by surfactant-assisted electrochemical method, followed by deposition of a PEDOT:PSS layer. The hybrid-film formation is primarily based on coulombic interactions between the surface hydroxyl groups of tungsten oxide and the positively charged centers on the polymer backbone; this has been confirmed by electron microscopy and X-ray diffraction. High-resolution transmission electron microscopy reveals that the tungsten-oxide host with a monoclinic unit cell resides along with the amorphous domains of PEDOT:PSS. The hybrid film, being a dual electrochrome, exhibits a much larger coloring efficiency ͑227 cm 2 C −1 at 600 nm͒, a higher redox activity ͑larger currents for ion ingress and egress are obtained within the same potential range͒, and, most importantly, a superior electrochemical cycling stability when compared to the neat polymer film. While the pristine polymer film lifts off irrevocably from the substrate upon 3000 cycles of coloring and bleaching, the hybrid film sustains about 5000 cycles, albeit with some changes in the nanoparticulate morphology, elemental composition, and development of some new artifacts on the film surface. The integration of organic and inorganic materials has aroused much interest in the scientific community for the use of hybrid organic-inorganic materials for catalysis, chiral synthesis, and enhancing electronic conductivity and electro-optical properties.1,2 To this end, this report describes a bilayer deposition of two different materials, an n-type semiconductor oxide, tungsten oxide ͑WO 3 ͒, and a p-type semiconductor, polymer ͑PEDOT:PSS͒, to yield a hybrid film and how its structure and composition influences the electrochemical and optical response and chemical stability of the film generated thereof. Since the discovery of electrochromism in WO 3 by Deb, 3 this oxide has been extensively investigated and has drawn considerable attention because of its application in electrochromic cells like smart windows, high-contrast displays, antiglare rearview mirrors, and so forth.4-6 PEDOT:PSS is one of the most widely studied electroactive polymers to date because of its excellent film forming ability, high conductivity, and high contrast ratio. [7][8][9] We found that the polymer forms a well-adherent uniform layer when deposited onto the WO 3 film, which indicates a strong affinity between the inorganic and organic species. The hybrid film offers the potential of realizing practical improvements of charge-transfer quanta through the bilayer/electrolyte interface and its reversibility as well. Furthermore, in the ever-growing field of solid-state electrochemical devices, the limited understanding of charge-transfer phenomena at the electrode-electrolyte interface is often a factor restricting operational lifetimes.In an approach to address these issues, in the past, PEDOT has been functio...

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Windows

Bell¹,

Skryabin²,

Matthews³

2002

Encyclopedia of Smart Materials

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The term Smart Window was introduced in the mid 1980s to describe optically switchable electrochromic glazings. These devices exemplify the fundamental characteristic of all “smart windows”: controllable variation in the optical transmittance of the window. The variation in optical transmittance of electrochromic smart windows occurs through the simultaneous injection of electrons and ions into an electrochromic material. This leads to the development of either a broad absorption band or a reflection edge (depending on the details of the material preparation) that leads to a low transmittance state. The process is reversible; extraction of the ions and electrons returns the material to a transparent state. The control of the process is accomplished by applying a small voltage (or passing a small current) that controls ion injection and extraction. Since the initial discovery of electrochromism in thin film WO 3 in 1969, an enormous amount of research has been directed toward the goal of large area switchable windows for architectural applications. This initially focused on electrochromic systems that covered a wide range of materials and device structures. During the 1980s and subsequently, several alternate optical switching systems were developed that fall into the general category of smart windows. These include other electrically activated systems such as suspended particle devices and phase dispersed liquid crystals temperature controlled switchable devices such as thermochromic and thermotropic devices, and recently developed gasochromic devices that are controlled by using reducing or oxidizing gas mixtures in a window unit.

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Electrochromic displays based on WO3

Cited by 102 publications

References 34 publications

In-situ spectroscopic studies of electrochromic hydrated nickel oxide films

In-situ spectroscopic studies of electrochromic hydrated nickel oxide films

Nanostructured Tungsten Oxide-Poly(3,4-ethylenedioxythiophene):Poly(styrenesulfonate) Hybrid Films: Synthesis, Electrochromic Response, and Durability Characteristics

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