Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications

Michael D. Kelzenberg, Shannon W. Boettcher, Jan A. Petykiewicz, Daniel B. Turner-Evans, Morgan C. Putnam, Emily L. Warren, Joshua M. Spurgeon, Ryan M. Briggs, Nathan S. Lewis, Harry A. Atwater

Research output: Contribution to journalArticle

1101 Citations (Scopus)

Abstract

Si wire arrays are a promising architecture for solar-energy-harvesting applications, and may offer a mechanically flexible alternative to Si wafers for photovoltaics. To achieve competitive conversion efficiencies, the wires must absorb sunlight over a broad range of wavelengths and incidence angles, despite occupying only a modest fraction of the arrays volume. Here, we show that arrays having less than 5% areal fraction of wires can achieve up to 96% peak absorption, and that they can absorb up to 85% of day-integrated, above-bandgap direct sunlight. In fact, these arrays show enhanced near-infrared absorption, which allows their overall sunlight absorption to exceed the ray-optics light-trapping absorption limit for an equivalent volume of randomly textured planar Si, over a broad range of incidence angles. We furthermore demonstrate that the light absorbed by Si wire arrays can be collected with a peak external quantum efficiency of 0.89, and that they show broadband, near-unity internal quantum efficiency for carrier collection through a radial semiconductor/liquid junction at the surface of each wire. The observed absorption enhancement and collection efficiency enable a cell geometry that not only uses 1/100th the material of traditional wafer-based devices, but also may offer increased photovoltaic efficiency owing to an effective optical concentration of up to 20 times.

Original languageEnglish
Pages (from-to)239-244
Number of pages6
JournalNature materials
Volume9
Issue number3
DOIs
Publication statusPublished - Mar 2010

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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    Kelzenberg, M. D., Boettcher, S. W., Petykiewicz, J. A., Turner-Evans, D. B., Putnam, M. C., Warren, E. L., Spurgeon, J. M., Briggs, R. M., Lewis, N. S., & Atwater, H. A. (2010). Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications. Nature materials, 9(3), 239-244. https://doi.org/10.1038/nmat2635