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The Importance of O...
The Importance of Oxygen Vacancies in Nanocrystalline WO3−x ThinFilms Prepared by DC Magnetron Sputtering for Achieving High Photoelectrochemical Efficiency
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- Johansson, Malin B. (author)
- Uppsala universitet,Fasta tillståndets fysik
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- Mattsson, Andreas (author)
- Uppsala universitet,Fasta tillståndets fysik
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- Lindquist, Sten-Eric (author)
- Uppsala universitet,Fasta tillståndets fysik
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- Niklasson, Gunnar A. (author)
- Uppsala universitet,Fasta tillståndets fysik
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- Österlund, Lars (author)
- Uppsala universitet,Fasta tillståndets fysik
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(creator_code:org_t)
- 2017-03-27
- 2017
- English.
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In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 121:13, s. 7412-7420
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Abstract
Subject headings
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- The photoelectrochemical properties of tungsten oxide thinfilms with different stoichiometry (WO3−x) and thickness were investigated.The films were sputtered in O2/Ar gas (ratio 0.43) on glass substrates coatedwith fluorine-doped tin dioxide at two sputter pressures, Ptot = 10 and 30mTorr, yielding O/W ratios of the films, averaged over three samples, of 2.995and 2.999 (x ∼ 0.005 and x ∼ 0.001), respectively. The films were characterizedby X-ray diffraction, scanning electron microscopy, and spectrophotometry.The 10 mTorr samples showed large absorption in the near-infrared (NIR)range, whereas the 30 mTorr samples had a small absorption in this region. Theconcentration of oxygen vacancy band gap states was estimated from cyclicvoltammetry and was found to correlate with the optical absorption in the NIRregion. The incident photon to current efficiency for illumination from theelectrolyte side (IPCEEE) and substrate electrode side (IPCESE) showed higherefficiency for the more stoichiometric films, indicating that oxygen vacancies in the band gap act as recombination centers.Surprisingly high values of IPCEEE and IPCESE were found, and it was concluded that efficient charge separation and transporttake place almost throughout the entire film even for film electrodes as thick as 2 μm. Analysis of the spectral distribution of thephotoresponse (action spectra) using an extended Gärtner−Butler model to calculate the IPCE for front-side and back-sideillumination was performed and showed that the diffusion length is large, of the order of the depletion layer thickness.
Subject headings
- NATURVETENSKAP -- Kemi -- Fysikalisk kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Physical Chemistry (hsv//eng)
Keyword
- Photoelectrochemistry
- WO3
- Oxygen vacancy
- thin films
- Chemistry with specialization in Physical Chemistry
- Kemi med inriktning mot fysikalisk kemi
- Teknisk fysik med inriktning mot materialvetenskap
- Engineering Science with specialization in Materials Science
Publication and Content Type
- ref (subject category)
- art (subject category)
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