Enhanced Absorption and <1% Spectrum-and-Angle-Averaged Reflection in Tapered Microwire Arrays

Sisir Yalamanchili, Hal S. Emmer, Katherine T. Fountaine, Christopher T. Chen, Nathan S Lewis, Harry A. Atwater

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

We report ordered, high aspect ratio, tapered Si microwire arrays that exhibit an extremely low angular (0° to 50°) and spectrally averaged reflectivity of <1% of the incident 400-1100 nm illumination. After isolating the microwires from the substrate with a polymer infill and peel off process, the arrays were found to absorb 89.1% of angular averaged incident illumination (0° to 50°) in the equivalent volume of a 20 μm thick Si planar slab, reaching 99.5% of the classical light trapping limit between 400 and 1100 nm. We explain the broadband absorption by enhancement in coupling to waveguide modes due to the tapered microstructure of the arrays. Time-resolved microwave photoconductivity decay measurements yielded charge-carrier lifetimes of 0.75 μs (more than an order of magnitude higher than vapor-liquid-solid-grown Si microwires) in the tapered microwires, resulting in an implied Voc of 0.655 V. The high absorption and high aspect ratio in these ordered microwire arrays make them an attractive platform for high-efficiency thin-film crystalline Si solar cells and as well as for the photoelectrochemical production of fuels from sunlight.

Original languageEnglish
Pages (from-to)1854-1861
Number of pages8
JournalACS Photonics
Volume3
Issue number10
DOIs
Publication statusPublished - Oct 19 2016

Fingerprint

Lighting
Aspect ratio
Carrier lifetime
Sunlight
Photoconductivity
Microwaves
high aspect ratio
Charge carriers
Solar cells
Polymers
Waveguides
illumination
Vapors
Crystalline materials
Light
Thin films
Microstructure
Liquids
Substrates
sunlight

Keywords

  • absorption
  • carrier lifetime
  • ICPRIE
  • microwires
  • reflection
  • silicon
  • surface passivation
  • waveguide

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biotechnology
  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering

Cite this

Yalamanchili, S., Emmer, H. S., Fountaine, K. T., Chen, C. T., Lewis, N. S., & Atwater, H. A. (2016). Enhanced Absorption and <1% Spectrum-and-Angle-Averaged Reflection in Tapered Microwire Arrays. ACS Photonics, 3(10), 1854-1861. https://doi.org/10.1021/acsphotonics.6b00370

Enhanced Absorption and <1% Spectrum-and-Angle-Averaged Reflection in Tapered Microwire Arrays. / Yalamanchili, Sisir; Emmer, Hal S.; Fountaine, Katherine T.; Chen, Christopher T.; Lewis, Nathan S; Atwater, Harry A.

In: ACS Photonics, Vol. 3, No. 10, 19.10.2016, p. 1854-1861.

Research output: Contribution to journalArticle

Yalamanchili, S, Emmer, HS, Fountaine, KT, Chen, CT, Lewis, NS & Atwater, HA 2016, 'Enhanced Absorption and <1% Spectrum-and-Angle-Averaged Reflection in Tapered Microwire Arrays', ACS Photonics, vol. 3, no. 10, pp. 1854-1861. https://doi.org/10.1021/acsphotonics.6b00370
Yalamanchili, Sisir ; Emmer, Hal S. ; Fountaine, Katherine T. ; Chen, Christopher T. ; Lewis, Nathan S ; Atwater, Harry A. / Enhanced Absorption and <1% Spectrum-and-Angle-Averaged Reflection in Tapered Microwire Arrays. In: ACS Photonics. 2016 ; Vol. 3, No. 10. pp. 1854-1861.
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