Impedance Spectroscopy of Electrochromic Hydrous Tungsten Oxide Films
Tungsten oxide is a widely used electrochromic material with important applications in variable-transmittance smart windows as well as in other optoelectronic devices. Here we report on electrochemical impedance spectroscopy applied to hydrous electrochromic tungsten oxide films in a wide range of a...
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doaj-db1da64ac17a4c9b88e3a2edf44d54642021-09-26T00:02:52ZengMDPI AGElectronic Materials2673-39782021-07-0122231232310.3390/electronicmat2030022Impedance Spectroscopy of Electrochromic Hydrous Tungsten Oxide FilmsEsat Pehlivan0Claes G. Granqvist1Gunnar A. Niklasson2Department of Materials Science and Engineering, The Ångström Laboratory, Uppsala University, P.O. Box 35, SE-75103 Uppsala, SwedenDepartment of Materials Science and Engineering, The Ångström Laboratory, Uppsala University, P.O. Box 35, SE-75103 Uppsala, SwedenDepartment of Materials Science and Engineering, The Ångström Laboratory, Uppsala University, P.O. Box 35, SE-75103 Uppsala, SwedenTungsten oxide is a widely used electrochromic material with important applications in variable-transmittance smart windows as well as in other optoelectronic devices. Here we report on electrochemical impedance spectroscopy applied to hydrous electrochromic tungsten oxide films in a wide range of applied potentials. The films were able to reversibly bleach and color upon electrochemical cycling. Interestingly, the bleaching potential was found to be significantly higher than in conventional non-hydrous tungsten oxide films. Impedance spectra at low potentials showed good agreement with anomalous diffusion models for ion transport in the films. At high potentials, where little ion intercalation takes place, it seems that parasitic side reactions influence the spectra. The potential dependence of the chemical capacitance, as well as the ion diffusion coefficient, were analyzed. The chemical capacitance is discussed in terms of the electron density of states in the films and evidence was found for a band tail extending below the conduction band edge.https://www.mdpi.com/2673-3978/2/3/22electrochromismoptoelectronic coatingssmart windowshydrous tungsten oxideimpedance spectroscopychemical capacitance |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Esat Pehlivan Claes G. Granqvist Gunnar A. Niklasson |
spellingShingle |
Esat Pehlivan Claes G. Granqvist Gunnar A. Niklasson Impedance Spectroscopy of Electrochromic Hydrous Tungsten Oxide Films Electronic Materials electrochromism optoelectronic coatings smart windows hydrous tungsten oxide impedance spectroscopy chemical capacitance |
author_facet |
Esat Pehlivan Claes G. Granqvist Gunnar A. Niklasson |
author_sort |
Esat Pehlivan |
title |
Impedance Spectroscopy of Electrochromic Hydrous Tungsten Oxide Films |
title_short |
Impedance Spectroscopy of Electrochromic Hydrous Tungsten Oxide Films |
title_full |
Impedance Spectroscopy of Electrochromic Hydrous Tungsten Oxide Films |
title_fullStr |
Impedance Spectroscopy of Electrochromic Hydrous Tungsten Oxide Films |
title_full_unstemmed |
Impedance Spectroscopy of Electrochromic Hydrous Tungsten Oxide Films |
title_sort |
impedance spectroscopy of electrochromic hydrous tungsten oxide films |
publisher |
MDPI AG |
series |
Electronic Materials |
issn |
2673-3978 |
publishDate |
2021-07-01 |
description |
Tungsten oxide is a widely used electrochromic material with important applications in variable-transmittance smart windows as well as in other optoelectronic devices. Here we report on electrochemical impedance spectroscopy applied to hydrous electrochromic tungsten oxide films in a wide range of applied potentials. The films were able to reversibly bleach and color upon electrochemical cycling. Interestingly, the bleaching potential was found to be significantly higher than in conventional non-hydrous tungsten oxide films. Impedance spectra at low potentials showed good agreement with anomalous diffusion models for ion transport in the films. At high potentials, where little ion intercalation takes place, it seems that parasitic side reactions influence the spectra. The potential dependence of the chemical capacitance, as well as the ion diffusion coefficient, were analyzed. The chemical capacitance is discussed in terms of the electron density of states in the films and evidence was found for a band tail extending below the conduction band edge. |
topic |
electrochromism optoelectronic coatings smart windows hydrous tungsten oxide impedance spectroscopy chemical capacitance |
url |
https://www.mdpi.com/2673-3978/2/3/22 |
work_keys_str_mv |
AT esatpehlivan impedancespectroscopyofelectrochromichydroustungstenoxidefilms AT claesggranqvist impedancespectroscopyofelectrochromichydroustungstenoxidefilms AT gunnaraniklasson impedancespectroscopyofelectrochromichydroustungstenoxidefilms |
_version_ |
1717367248391241728 |