Investigation To The Electrochromism Of a-W0   3    In Single Films And All-Solid-State Devices

Bange, K.; Keller, Reimund; Wagner, W.; Rauch, F.

doi:10.1117/12.949913

Cited by 4 publications

(2 citation statements)

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“…On the other hand, our value is higher than that of WO 3 single crystal (n 2X5) [31], amorphous and crystalline films (n 2X4) prepared by rf sputtering showing oxygen content independence [32]. Lower values in the range (2 to 2.3) were reported for amorphous films prepared by thermal evaporation [28,32] while for dark blue coloured films a very low value of n 1X7 was obtained [33]. A value of n 2X43 for crystalline WO 3 was obtained by Kaneko et al [20] using the sputtering technique and they showed that the refractive index was independent of O 2 concentration.…”

Section: Resultscontrasting

confidence: 77%

“…The occupancy of the conduction band will tend to increase the optical absorption threshold. The intraband transition from these states to a higher conduction band [33] has nothing to do with the value of the gap, but it is also associated with formation of the hydrogen tungsten bronze. The observed slight increase of the gap may also be attributed to the formation of a new phase or variation of film stoichiometry associated with transition metal oxides.…”

Section: Optical Constantsmentioning

confidence: 95%

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Preparation and Properties of Electrochemically Deposited Tungsten Oxide Films

Hutchins

Kamel

El-Kadry

et al. 1999

phys. stat. sol. (a)

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Tungsten oxide films of thicknesses 1095 nm have been cathodically deposited onto ITO coated glass substrates kept at room temperature, at a rate of 13 nm/min. The electrolyte solution has been prepared by adding 0.025 M tungsten (dissolved in 30% H2O2) to 0.25 M H2SO4. XRD observations showed that all films are amorphous. The film resistivity at room temperature was found to be 9 × 106 Ω cm, and from the resistivity–temperature dependence, the thermal activation energy was obtained as 0.29 eV. The refractive index, n, and the extinction coefficient, k, have been computed from the corrected transmittance and reflectance over the spectral range 400 to 800 nm. Absorption versus photon energy curves give an indirect transition with optical energy gap of 3.25 and 3.36 eV for the as‐deposited and coloured states, respectively. The electrochromic properties of the prepared films have been investigated in situ and both solar transmittance and optical density have been evaluated in the coloured and bleached states. The electrochemical coloration and bleaching were performed in an electrolyte of 0.4 M H2SO4 solution. The coloration efficiency has been evaluated as 50 cm2/C at λ = 600 nm, which is comparable with the results obtained from films prepared by other methods.

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