Efficient Reductive or Oxidative Current Flow across 100 µm Using an Si Photoelectrode under High Level Injection

Ming X. Tan, C. N. Kenyon, Wolf Christian, A. Wilisch, Nathan S Lewis

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The photoelectrochemistry of Si/CH3OH contacts has been investigated under high level injection conditions. Exposure of Si samples having low doping levels (1013cm-3) and long minority carrier lifetimes (>1 ms) to modest steady-state illumination levels has produced high level injection conditions and minimal electric fields at the solid/liquid contact. Under these conditions, the solid is analogous to a large molecule, with both electrons and holes available for interfacial charge transfer (and recombination) at the solid/liquid contact. In principle, photocurrents of either sign are possible in such samples. Vectorial charge separation with a high quantum yield has been effected by selective removal of one carrier type at the back of the sample, in a fashion analogous to either oxidative or reductive quenching of a molecular excited state. Through specifying the back contact connections, the sign of the photocurrent at the solid/liquid interface, 100 µm from the initial quenching site, has been manipulated. Charge separation with high quantum yields and with = 10% photoelectrode energy conversion efficiencies under solar simulation has been achieved using this approach.

Original languageEnglish
Pages (from-to)L62-L64
JournalJournal of the Electrochemical Society
Issue number4
Publication statusPublished - 1995


ASJC Scopus subject areas

  • Electrochemistry
  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials
  • Materials Chemistry
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films

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