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Title: A Silicon Ratchet to Produce Power from Below-Bandgap Photons

Abstract

Abstract This paper computationally demonstrates a new photovoltaic mechanism that generates power from incoherent, below‐bandgap (THz) excitations of conduction band electrons in silicon. A periodic sawtooth potential, realized through elastic strain gradients along a 100 nm thick Si slab, biases the oscillatory motion of excited electrons, which preferentially jump and relax into the adjacent period on the right to generate a net current. The magnitude of the ratchet current increases with photon energy (20, 50, and 100 meV) and irradiance (≈MW cm −2 ), which control the probability of photon scattering, and peaks as a function of the well depth of the ratchet potential, and the dominant mode of energy loss (the 62 meV intervalley phonon). The internal power conversion efficiency of the ratchet has a maximum of 0.0083% at a photon energy of 100 meV, due to inefficiencies caused by isotropic scattering. This new photovoltaic mechanism uses wasted below‐bandgap absorptions to enhance the directional diffusion of charge carriers and could be used to augment the efficiency of traditional photovoltaics.

Authors:
 [1];  [1];  [1];  [1]; ORCiD logo [1]
  1. Northwestern Univ., Evanston, IL (United States)
Publication Date:
Research Org.:
Northwestern Univ., Evanston, IL (United States). Energy Frontier Research Center (EFRC) Center for Bio-Inspired Energy Science (CBES)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1469980
Alternate Identifier(s):
OSTI ID: 1375821
Grant/Contract Number:  
SC0000989
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Advanced Energy Materials
Additional Journal Information:
Journal Volume: 7; Journal Issue: 22; Related Information: CBES partners with Northwestern University (lead); Harvard University; New York University; Pennsylvania State University; University of Michigan; University of Pittsburgh; Journal ID: ISSN 1614-6832
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; below‐bandgap; infrared; photovoltaics; ratchet; silicon

Citation Formats

Lau, Bryan, Kedem, Ofer, Kodaimati, Mohamad, Ratner, Mark A., and Weiss, Emily A. A Silicon Ratchet to Produce Power from Below-Bandgap Photons. United States: N. p., 2017. Web. doi:10.1002/aenm.201701000.
Lau, Bryan, Kedem, Ofer, Kodaimati, Mohamad, Ratner, Mark A., & Weiss, Emily A. A Silicon Ratchet to Produce Power from Below-Bandgap Photons. United States. https://doi.org/10.1002/aenm.201701000
Lau, Bryan, Kedem, Ofer, Kodaimati, Mohamad, Ratner, Mark A., and Weiss, Emily A. 2017. "A Silicon Ratchet to Produce Power from Below-Bandgap Photons". United States. https://doi.org/10.1002/aenm.201701000. https://www.osti.gov/servlets/purl/1469980.
@article{osti_1469980,
title = {A Silicon Ratchet to Produce Power from Below-Bandgap Photons},
author = {Lau, Bryan and Kedem, Ofer and Kodaimati, Mohamad and Ratner, Mark A. and Weiss, Emily A.},
abstractNote = {Abstract This paper computationally demonstrates a new photovoltaic mechanism that generates power from incoherent, below‐bandgap (THz) excitations of conduction band electrons in silicon. A periodic sawtooth potential, realized through elastic strain gradients along a 100 nm thick Si slab, biases the oscillatory motion of excited electrons, which preferentially jump and relax into the adjacent period on the right to generate a net current. The magnitude of the ratchet current increases with photon energy (20, 50, and 100 meV) and irradiance (≈MW cm −2 ), which control the probability of photon scattering, and peaks as a function of the well depth of the ratchet potential, and the dominant mode of energy loss (the 62 meV intervalley phonon). The internal power conversion efficiency of the ratchet has a maximum of 0.0083% at a photon energy of 100 meV, due to inefficiencies caused by isotropic scattering. This new photovoltaic mechanism uses wasted below‐bandgap absorptions to enhance the directional diffusion of charge carriers and could be used to augment the efficiency of traditional photovoltaics.},
doi = {10.1002/aenm.201701000},
url = {https://www.osti.gov/biblio/1469980}, journal = {Advanced Energy Materials},
issn = {1614-6832},
number = 22,
volume = 7,
place = {United States},
year = {Tue Aug 22 00:00:00 EDT 2017},
month = {Tue Aug 22 00:00:00 EDT 2017}
}

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Cited by: 5 works
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