Comparison between electrochromic and photochromic coloration efficiency of tungsten oxide thin films

Bechinger, Clemens; Burdis, M. S.; Zhang, Ji‐Guang

doi:10.1016/s0038-1098(96)00703-x

Cited by 147 publications

(76 citation statements)

References 18 publications

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“…The coloration efficiency of WO 3−x (x < 0.4) films has been reported to increase with increasing O deficiency. 87 Their typical blue coloration has been correlated with a broad absorption band with a maximum at 900 nm (∼1.38 eV), 78,79 although this feature has been observed in amorphous films. Photoluminiscence (PL) spectra 88 exhibited an emission peak at 550 nm (∼2.26 eV), and photoelectron measurements 79,89 confirmed the presence of a defect state attributed to O vacancies at ∼2 eV above the VB.…”

Section: B Womentioning

confidence: 99%

Defect calculations in semiconductors through a dielectric-dependent hybrid DFT functional: The case of oxygen vacancies in metal oxides

Gerosa

Bottani

Caramella

et al. 2015

The Journal of Chemical Physics

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We investigate the behavior of oxygen vacancies in three different metal-oxide semiconductors\ud (rutile and anatase TiO2, monoclinic WO3, and tetragonal ZrO2) using a recently proposed hybrid\ud density-functional method in which the fraction of exact exchange is material-dependent but obtained\ud ab initio in a self-consistent scheme. In particular, we calculate charge-transition levels relative to the\ud oxygen-vacancy defect and compare computed optical and thermal excitation/emission energies with\ud the available experimental results, shedding light on the underlying excitation mechanisms and related\ud materials properties. We find that this novel approach is able to reproduce not only ground-state\ud properties and band structures of perfect bulk oxide materials but also provides results consistent\ud with the optical and electrical behavior observed in the corresponding substoichiometric defective\ud systems. C 2015 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.493180

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Section: B Womentioning

confidence: 99%

Defect calculations in semiconductors through a dielectric-dependent hybrid DFT functional: The case of oxygen vacancies in metal oxides

Gerosa

Bottani

Caramella

et al. 2015

The Journal of Chemical Physics

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“…13) Under the absorption of light these small polarons can hop from sites A to B. This process which is responsible for the color in tungsten oxide is referred as intervalence transfer and can be expressed as: 14) h…”

Section: Morphologies Of Tungsten Oxide Nanoparticlesmentioning

confidence: 99%

Synthesis of Tungsten Oxide Particles by Chemical Deposition Method

Wei

Teoh

et al. 2007

Mater. Trans.

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Due to the high potential of photoconductive behavior used in electrochromic and sensor devices, tungsten oxide (WO 3 ) is the most promising candidate applied for electrochromic materials, gas sensors, and dye sensitized solar cells. Adsorbing the visible blue light by tungsten oxide nanoparticles would thus be used efficiently to enhance the sun-light harvest efficiency. Recent investigations have been promoted by new methods of ultrafine powder production and their applications. Nanocrystalline tungsten oxide can be prepared by sputtering methods, gas condensation methods, and chemical deposition method. In this study, we would like to prepare of tungsten oxide nanoparticles by chemical deposition method and investigate the experimental parameters of various organic solutions and discuss the relationship between absorbance spectra and which by chemical deposition method. Purged O 2 into the various solvent (i.e. DMF and acetylacetone solution), WCl 6 was added into the solvent slowly and stirred vigorously. During the filtration process solutions were characterized and analyzed by particles size distribution, UV-visible absorption, and TEM observation. The size of tungsten oxide particles synthesized in DMF is smaller than that in acetylacetone solutions from TEM observation. These results may be related to particle sizes or agglomerated behavior of tungsten oxide. In the photochromic data, it exhibits absorbance result due to valence change of tungsten ion and photochromic effect of tungsten oxide nanoparticles. Since some papers also have been reported that the highest intensity of the solar spectrum is in the blue region, the modification of the oxide semiconductor for blue-light absorption will effectively increase the photon harvest from the incident sunlight and thus generate more electronhole pairs in addition to those from dyes. It would be appropriately applied in the design of solar cell devices.

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“…More recently, it has been argued that substoichiometric a-WO y ͑y Ͻ 3͒ contains W 4+ ions together with the W 6+ ones. [8][9][10] states give a major contribution to the optical absorption, which increases with the degree of substoichiometry. Hence, the coloration efficiency would increase with increasing substoichiometry, as observed by Lee et al 10 In addition, optical measurements at a single wavelength have been claimed to support this model.…”

Section: Introductionmentioning

confidence: 99%

Optical absorption in lithiated tungsten oxide thin films: Experiment and theory

Berggren

Jonsson

Niklasson

2007

Journal of Applied Physics

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Amorphous tungsten oxide exhibits electrochromism when intercalated with protons, lithium, sodium, and other ions. Thin films of the material were prepared by dc magnetron sputtering and then electrochemically intercalated with lithium. The optical absorption in the wavelength range of 300-2500 nm was measured for a number of lithium concentrations. The optical absorption shows a maximum for lithium/tungsten ratios of 0.3-0.5. The optical spectra can be fitted by a superposition of three Gaussian peaks, representing the three possible electronic transitions between W 6+ , W 5+ , and W 4+ sites. The variation of the peak strength with lithium concentration is consistent with an extended site-saturation theory.

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Comparison between electrochromic and photochromic coloration efficiency of tungsten oxide thin films

Cited by 147 publications

References 18 publications

Defect calculations in semiconductors through a dielectric-dependent hybrid DFT functional: The case of oxygen vacancies in metal oxides

Defect calculations in semiconductors through a dielectric-dependent hybrid DFT functional: The case of oxygen vacancies in metal oxides

Synthesis of Tungsten Oxide Particles by Chemical Deposition Method

Optical absorption in lithiated tungsten oxide thin films: Experiment and theory

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