Optical properties of electrochromic vanadium pentoxide

Cogan, Stuart F.; Nguyen, Nguyet Minh; Perrotti, S. J.; Rauh, R. D.

doi:10.1063/1.344432

Cited by 184 publications

(117 citation statements)

References 14 publications

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“…The calculated width of the valence band is equal to about 0.6 eV [25] and this value is consistent with the experimental values, both from XPS and UPS experiments [23,60]. The width of the energy gap for V 2 O 5 bulk determined by photoemission experiments [61], optical adsorption [62] and optical reflectance [63] is equal to 2.35, 2.30, and 2.38 eV, respectively, which confirms its semiconductor nature. The theoretical gap values from DFT calculations for the crystal [22] and for the (010) surface amount to 1.9 eV and 2.1 eV and are surprisingly close to the experiments [61][62][63] in view of the deficiency of density functional theory to account for gap values in general.…”

Section: The V 2 O 5 (010) Surface Clusterssupporting

confidence: 75%

Electronic Structure of Unsaturated V2O5(001) and (100) Surfaces: Ab Initio Density Functional Theory Studies

2009

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Vanadium oxides based materials are well known to play an active role as catalysts in many chemical processes of technological importance like for example hydrocarbon oxidation reactions or selective catalytic reduction of NO x in the presence of ammonia. Usually the (010) surface is pointed out as the most important, however one has to underline that other low-indices surfaces are by far less studied. In the present study the electronic structure of V 2 O 5 (001) and (100) surfaces are determined by ab initio DFT methods using gradient-corrected RPBE exchange-correlation functional. Detailed analyses of the electronic structure of each cluster are performed using charge density distributions, Mayer bond orders, electrostatic potential maps, character of frontier orbitals, and density of states (total as well as partial, atom projected). Results of the calculations show that overall negative charge of the surface oxygen sites scales with their coordination independent of the surface orientation. Terminal oxygen O(1) is charged the least negatively while doubly coordinated atoms -O(2) and O e (2) have charge twice as large. This indicates that bridging (for (001) and (100) netplanes) and edging (only for (001) netplane) oxygen sites are more nucleophilic than terminal vanadyl sites, which becomes important in view of the reactivity of the different sites for surface chemical reactions. Vanadium atoms present at these surfaces are positively charged (electrophilic) and may play a role of electron acceptors. The unsaturated surfaces show a strong tendency to surface relaxation that manifest by large relaxation energies.

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Section: The V 2 O 5 (010) Surface Clusterssupporting

confidence: 75%

Electronic Structure of Unsaturated V2O5(001) and (100) Surfaces: Ab Initio Density Functional Theory Studies

2009

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“…Transition metal oxides (TMOs) in thin-film configuration with diverse structures and chromogenic properties have been the foci of the research community in the outlook of their potential applications in the current science and technology [6]. Among the other chromogenic materials, vanadium pentoxide (V 2 O 5 ) in thin-film configuration is one of the TMOs, which has been receiving much attention owing to its quite motivating structural, chemical and chromogenic properties and exceptional industrial applications such as electrochromic devices and optical memory devices [7][8][9]. Most of the researchers have prepared thin films of V 2 O 5 on various solid substrates by different thin-film deposition techniques and investigated their microstructural, optical, electrochromic and electrochemical properties in detail [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic and electrochromic properties of activated reactive evaporated nano-crystalline V2O5 thin films grown on flexible substrates

2013

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Vanadium pentoxide (V 2 O 5 ) thin films were grown on indium tin oxide-coated flexible Kapton substrates by homebuilt activated reactive evaporation technique. Film depositions were carried out at optimised oxygen partial pressure of 1 × 10 −3 Torr and plasma power of 8 W, and we investigated their microstructural and optoelectrochromic properties as a function of substrate temperature. The V 2 O 5 films grown at T s = 473 K exhibited a nano-crystalline nature as evidenced from X-ray diffraction, atomic force microscopy and Raman studies. The nanocrystalline films composed of vertical elliptical-shaped grainy morphology demonstrated a high optical transmittance of 75% with an estimated optical bandgap of 2.38 eV. The dry lithiated nano-crystalline V 2 O 5 films demonstrated an optical modulation of 36.1% with a coloration efficiency value of 26.2 cm 2 /C at a wavelength of 550 nm. As-deposited nano-crystalline V 2 O 5 thin films demonstrated a constant discharge capacity of about 60 μAh cm −2 μm −1 for a few cycles at room temperature in the potential window of 4.0 to 2.5 V.

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“…Manuscript submitted Feb. 27, 1990; revised manuscript received Aug. 14, 1990. This was Paper 627 presented at the Hollywood, FL, Meeting of the Society, Oct. [15][16][17][18][19][20] 1989.…”

Section: Acknowledgmentsmentioning

confidence: 99%

“…V205 has been selected as a counterelectrode because it is a good lithium insertion material and is fairly transparent as * Electrochemical Society Active Member. a thin film (12)(13)(14)(15). The reversible insertion reaction can be written as follows…”

Section: Ya + + Ye-+ Mo= --~ Aymo=mentioning

confidence: 99%

Electrochromic Window with Lithium Conductive Polymer Electrolyte

Baudry

Aegerter

Deroo

et al. 1991

J. Electrochem. Soc.

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An electrochromic window was built using WO3 as electrochromic material and V20~ as counterelectrode. Both were deposited onto ITO-coated glass panes by vacuum evaporation and were amorphous to x-ray diffraction. The electrolyte was a lithium-conducting polymer consisting of a poly(ethylene oxide)-lithium salt complex. The electrochemical characterization of electrodes was realized by cyclic voltammetry, coulometric titration, and impedance spectroscopy, which allowed the determination of the chemical diffusion coefficients of lithium into WO3 and V2Q. Potentiostatic cycling of the complete transmissive cell yields to a transmission variation from 41 to 13% at 633 nm with a response time of 10s at room temperature.Over the last two decades, much work has been dedicated to the study of electrochromism for its possible application in electro-optical devices (1, 2). However, some major problems such as slow switching time or layer corrosion have been encountered. Nevertheless, the realization of energy-efficient windows emerged a few years ago as a new interesting application in that field (3,4). In this latter kind of device, a response time of approximately 1 rain, easily attainable, is sufficient, and the memory effect provided by the electrochemical reaction is of great interest.Many insertion materials, e.g., metal transition oxides, exhibit electrochromic properties when deposited in thin films. Their optical properties are modified by electrochemical insertion of alkali cations or protons. The corresponding reaction can be written as yA + + ye-+ MO= --~ AyMO=Tungsten trioxide has been the most investigated electrochromic material (5, 6) and without any doubt is one of the most promising with respect to its electrochromic properties. Both proton and lithium insertion are possible. Although the chemical diffusion coefficient ofH § in WO3 is higher than that of Li § (7), it seems easier to realize a complete transmissive electrochromic device with lithium conductors than with protonic ones, as hydrogen gassing and layer corrosion in acid media are potential drawbacks in the protic system.Polymer electrolytes have been widely studied during the last ten years for high energy secondary solid-state batteries (8, 9). Their use in electrochromic devices is suitable since they can be fabricated as thin elastOmeric films, and do not present problems of leakage encountered with liquid electrolytes. Polyethylene oxide (PEO) complexes exhibit conductivities higher than 10 -5 ~-' cm -1 with both lithium and proton conduction (10, 11), giving rise to a fast switching time.Whereas the electrochromic material and a solid electrolyte are available, a suitable transparent counterelectrode is still to be found. Two different types of counterelectrode can be considered. It may be transparent in both oxidized and reduced states, but a "rocking chair" counterelectrode occurring at the same time as the electrochromic electrode may also be envisaged. In this case, the counterelectrode will color anodically if WO3 is used as ...

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Optical properties of electrochromic vanadium pentoxide

Cited by 184 publications

References 14 publications

Electronic Structure of Unsaturated V2O5(001) and (100) Surfaces: Ab Initio Density Functional Theory Studies

Electronic Structure of Unsaturated V2O5(001) and (100) Surfaces: Ab Initio Density Functional Theory Studies

Spectroscopic and electrochromic properties of activated reactive evaporated nano-crystalline V2O5 thin films grown on flexible substrates

Electrochromic Window with Lithium Conductive Polymer Electrolyte

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