&lt;title&gt;Coloration behavior of hybrid electrochromic films&lt;/title&gt;

Denesuk, M.; Cronin, John P.; Kennedy, S. R.; Law, K.; Nielson, G. F.; Uhlmann, D. R.

doi:10.1117/12.185416

Cited by 11 publications

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“…After 30 cycles, these films loose 45% (in relation to the maximum value) of the optical density and 20% of the inserted charge, and the coloration efficiency decreases by 35%. This significant drop in performance can be attributed to the instability of the amorphous network upon electrochemical stimuli. , By contrast, the partially crystalline films exhibit a comparatively good long-term stability. They show a decrease of ΔOD by only 16%, Q red by 5%, and η by 15%.…”

Section: Resultsmentioning

confidence: 99%

“…It turned out that the electrochromic properties of the highly crystalline material are particularly stable with respect to prolonged exposure to elevated temperatures. By contrast, the mesoporous amorphous and partially crystalline films show an irreversible performance degradation due to structural changes. ,, A closer look at the different parameters reveals further subtleties of their temperature dependence. For highly crystalline films, elevated operating temperatures (50 °C or 70 °C) even increase the charge capacity and the absorbance at 630 nm (Figure ).…”

Section: Resultsmentioning

confidence: 99%

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Electrochromic Stability of WO₃ Thin Films with Nanometer-Scale Periodicity and Varying Degrees of Crystallinity

2007

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Electrochromic tungsten oxide (WO 3 ) thin films with nanometer-scale porosity have been synthesized via a sol-gel procedure making use of evaporation-induced self-assembly. According to wide-angle X-ray scattering data combined with electrochemical analyses, the degree of crystallinity ranging from fully amorphous to 100% crystalline can be adjusted by straightforward annealing. The three-dimensional cubic pore structure is thereby almost not affected. Aside from the material characterization, in this work we specifically focus on the overall electrochemical and electrochromic behavior (coloration efficiency, charge capacity, etc.) upon changes in the operating temperature. As a main result, only the mesoporous highly crystalline WO 3 films display long-term cycling stability under realistic environmental conditions. We further demonstrate that sufficient crystallinity is needed to ensure stability of the inherent electrochemical properties at high operating temperatures (up to 70 °C). Thus, only the WO 3 films with a highly crystalline framework exhibit almost unchanged electrochemical/electrochromic characteristics after prolonged potentiostatic cycling and exposure to elevated operating temperatures. In contrast, amorphous and partially crystalline films suffer from irreversible performance degradation due to structural modifications.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Electrochromic Stability of WO₃ Thin Films with Nanometer-Scale Periodicity and Varying Degrees of Crystallinity

2007

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“…Many have studied crystalline and amorphous films, usually as measured by X-ray diffraction (XRD); however, XRD cannot distinguish low-to-medium volume fractions of crystallinity in thin tungsten oxide films when nanometer-sized crystals are present. Instead of considering only the extremes of crystallinity, we must now think in terms of volume fraction crystallinity, and size and orientation of crystallites. , …”

Section: Discussionmentioning

confidence: 99%

“…The sol−gel precursor solutions were prepared by dissolving a peroxotungstic ester derivative in anhydrous ethanol (PTE/EtOH = 0.24 gm/mL). The precursor solution also contained 32 mol % oxalic acid dihydrate, where the concentration is referenced to the tungsten metal content in the PTE. − The coatings were deposited by dipping indium tin oxide (ITO) coated (12Ω/□) glass into the solution under ambient atmosphere and withdrawing at a rate of 28 cm/min. The coatings were then dried under controlled relative humidity at 100 °C for 1 h.…”

Section: Methodsmentioning

confidence: 99%

Microstructure of Laser-Fired, Sol−Gel-Derived Tungsten Oxide Films

et al. 1996

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Half-micron-thick tungsten oxide films were deposited by the sol−gel method onto indium tin oxide (ITO) coated soda lime silicate substrates. Following a 100 °C prebake, the samples were fired with a carbon dioxide laser at a variety of power densities and translation speeds. The laser-fired tungsten oxide films were characterized by spectrophotometry, electrochemistry, multiangle ellipsometry, and transmission electron microscopy and compared to similar furnace-fired films. The data showed an increase in electrochromic response with increased firing temperature up to the point where crystallization of the tungsten oxide retarded electrochromic response. A window with graded electrochromic properties was made by laser firing.

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“…WO 3 is the most studied and best electrochromic material for EC applications. Its color changes from transparent or yellow to Denesuk et al [32] reported on WO3 films from the above sol preparation with additions of oxalic acid dihydrate. The films were inhomogeneous amorphous/crystalline hybrid structure containing small (~5 nm) regions of increased electron density.…”

Section: Materials For Electrocbromic Devicesmentioning

confidence: 95%

Electrochromism in materials prepared by the sol-gel process

Aegerter

Avellaneda

Pawlicka

et al. 1997

J Sol-Gel Sci Technol

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Abstract. Electrochromism is defined as the persistent but reversible optical change (usually transmission) produced electrochemically. The preparation by the sol-gel process of thin films made of amorphous or crystalline nanoparticles of WO3, V205, Nb205, TiO2, CeO2, Fe203 and mixed compounds such as WO3-TiO2, CeO2-TiO2, CeO2-SnO2, have opened remarkable new opportunities for obtaining electrochromic layers exhibiting large optical transmission variation in the UV, visible or infrared range and acceptable kinetics under H + or Li + insertion. In this paper we give an overview of what has been recently achieved in this field, with emphasis for cathodic electrochromic coatings of Nb205 and TiO2 composition. Finally we stress the future developments in this fast growing field.

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<title>Coloration behavior of hybrid electrochromic films</title>

Cited by 11 publications

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Electrochromic Stability of WO₃ Thin Films with Nanometer-Scale Periodicity and Varying Degrees of Crystallinity

Electrochromic Stability of WO₃ Thin Films with Nanometer-Scale Periodicity and Varying Degrees of Crystallinity

Microstructure of Laser-Fired, Sol−Gel-Derived Tungsten Oxide Films

Electrochromism in materials prepared by the sol-gel process

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<title>Coloration behavior of hybrid electrochromic films</title>

Cited by 11 publications

References 0 publications

Electrochromic Stability of WO3 Thin Films with Nanometer-Scale Periodicity and Varying Degrees of Crystallinity

Electrochromic Stability of WO3 Thin Films with Nanometer-Scale Periodicity and Varying Degrees of Crystallinity

Microstructure of Laser-Fired, Sol−Gel-Derived Tungsten Oxide Films

Electrochromism in materials prepared by the sol-gel process

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Product

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Electrochromic Stability of WO₃ Thin Films with Nanometer-Scale Periodicity and Varying Degrees of Crystallinity

Electrochromic Stability of WO₃ Thin Films with Nanometer-Scale Periodicity and Varying Degrees of Crystallinity