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Electrical and Photoelectrochemical Properties of WO_3/Si Tandem Photoelectrodes

Coridan, Robert H. and Shaner, Matthew and Wiggenhorn, Craig and Brunschwig, Bruce S. and Lewis, Nathan S. (2013) Electrical and Photoelectrochemical Properties of WO_3/Si Tandem Photoelectrodes. Journal of Physical Chemistry C, 117 (14). pp. 6949-6957. ISSN 1932-7447.

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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.

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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.
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Defense Advanced Research Projects Agency (DARPA)W911NF-09-2-0011
Department of Energy (DOE)DE-SC0004993
Caltech Molecular Materials Research CenterUNSPECIFIED
Record Number:CaltechAUTHORS:20130516-133146126
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Official Citation:Electrical and Photoelectrochemical Properties of WO3/Si Tandem Photoelectrodes Robert H. Coridan, Matthew Shaner, Craig Wiggenhorn, Bruce S. Brunschwig, and Nathan S. Lewis The Journal of Physical Chemistry C 2013 117 (14), 6949-6957
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38541
Deposited By: Jason Perez
Deposited On:20 May 2013 22:47
Last Modified:20 May 2013 22:47

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