Impedance Spectroscopy of Electrochromic Hydrous Tungsten Oxide Films
| Autor: | Claes-Göran Granqvist, Esat Pehlivan, Gunnar A. Niklasson |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
impedance spectroscopy
QA71-90 Materials science optoelectronic coatings Anomalous diffusion 020209 energy Diffusion chemical capacitance Analytical chemistry Materials Engineering 02 engineering and technology 021001 nanoscience & nanotechnology Electrochemistry Instruments and machines Capacitance Spectral line Ion Dielectric spectroscopy smart windows hydrous tungsten oxide Electrochromism Materialteknik 0202 electrical engineering electronic engineering information engineering electrochromism 0210 nano-technology |
| Zdroj: | Electronic Materials Volume 2 Issue 3 Pages 22-323 Electronic Materials, Vol 2, Iss 22, Pp 312-323 (2021) |
| ISSN: | 2673-3978 |
| DOI: | 10.3390/electronicmat2030022 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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