Optical, electrical, and solar energy-conversion properties of gallium arsenide nanowire-array photoanodes

Shu Hu, Chun Yung Chi, Katherine T. Fountaine, Maoqing Yao, Harry A. Atwater, P. Daniel Dapkus, Nathan S. Lewis, Chongwu Zhou

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Abstract

Periodic arrays of n-GaAs nanowires have been grown by selective-area metal-organic chemical-vapor deposition on Si and GaAs substrates. The optical absorption characteristics of the nanowire-arrays were investigated experimentally and theoretically, and the photoelectrochemical energy-conversion properties of GaAs nanowire arrays were evaluated in contact with one-electron, reversible, redox species in non-aqueous solvents. The radial semiconductor/liquid junction in the nanowires produced near-unity external carrier-collection efficiencies for nanowire-array photoanodes in contact with non-aqueous electrolytes. These anodes exhibited overall inherent photoelectrode energy-conversion efficiencies of ∼8.1% under 100 mW cm-2 simulated Air Mass 1.5 illumination, with open-circuit photovoltages of 590 ± 15 mV and short-circuit current densities of 24.6 ± 2.0 mA cm-2. The high optical absorption, and minimal reflection, at both normal and off-normal incidence of the GaAs nanowire arrays that occupy <5% of the fractional area of the electrode can be attributed to efficient incoupling into radial nanowire guided and leaky waveguide modes.

Original languageEnglish
Pages (from-to)1879-1890
Number of pages12
JournalEnergy and Environmental Science
Volume6
Issue number6
DOIs
Publication statusPublished - Jun 1 2013

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ASJC Scopus subject areas

  • Environmental Chemistry
  • Renewable Energy, Sustainability and the Environment
  • Nuclear Energy and Engineering
  • Pollution

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