Electrical and Photoelectrochemical Properties of WO_3/Si Tandem Photoelectrodes
Abstract
Tungsten trioxide (WO_3) has been investigated as a photoanode for water oxidation reactions in acidic aqueous conditions. Though WO_3 is not capable of performing unassisted solar-driven water splitting, WO_3 can in principle be coupled with a low band gap semiconductor, such as Si, to produce a stand-alone, tandem photocathode/photoanode p-Si/n-WO_3 system for solar fuels production. Junctions between Si and WO_3, with and without intervening ohmic contacts, were therefore prepared and investigated in detail. Thin films of n-WO_3 that were prepared directly on p-Si and n-Si substrates exhibited an onset of photocurrent at a potential consistent with expectations based on the band-edge alignment of these two materials predicted by Andersen theory. However, n-WO_3 films deposited on Si substrates exhibited much lower anodic photocurrent densities (0.02 mA cm^(–2) at 1.0 V vs SCE) than identically prepared n-WO_3 films that were deposited on fluorine-doped tin oxide (FTO) substrates (0.45 mA cm^(–2) at 1.0 V vs SCE). Deposition of n-WO_3 onto a thin layer of tin-doped indium oxide (ITO) that had been deposited on a Si substrate yielded anodic photocurrent densities that were comparable to those observed for n-WO_3 films that had been deposited onto FTO-coated glass. An increased photovoltage was observed when an n-Si/ITO Schottky junction was formed in series with the n-WO_3 film, relative to when the WO_3 was deposited directly onto the Si. Hence, inclusion of the ITO layer allowed for tandem photoelectrochemical devices to be prepared using n-WO_3 and n-Si as the light absorbers.
Additional Information
© 2013 American Chemical Society. Received: December 5, 2012; Revised: February 22, 2013; Published: March 15, 2013. Published In Issue April 11, 2013. We acknowledge the Defense Advanced Research Projects Agency (DARPA) Grant W911NF-09-2-0011 for support of R.H.C. and N.S.L. and the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award DE-SC0004993, for support of M.S., B.S.B., and N.S.L. We also acknowledge BP and the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology for support.Attached Files
Published - jp311947x.pdf
Supplemental Material - jp311947x_si_001.pdf
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Additional details
- Eprint ID
- 38541
- Resolver ID
- CaltechAUTHORS:20130516-133146126
- Defense Advanced Research Projects Agency (DARPA)
- W911NF-09-2-0011
- Department of Energy (DOE)
- DE-SC0004993
- BP
- Caltech Beckman Institute
- Created
-
2013-05-20Created from EPrint's datestamp field
- Updated
-
2021-11-09Created from EPrint's last_modified field
- Caltech groups
- JCAP