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Title: Effect of electric field on carrier escape mechanisms in quantum dot intermediate band solar cells

Abstract

Carrier escape and recombination from quantum dot (QD) states reduce the probability of two-step photon absorption (TSPA) by decreasing the available carrier population in the intermediate band (IB). In order to optimize the second photon absorption for future designs of quantum dot embedded intermediate band solar cells, this study combined the results of simulations and experiments to quantify the effect of electric field on the barrier height and the carrier escape from the QDs in InAs/GaAs quantum dot solar cells with five-layer QD superlattices. The electric field dependent effective barrier heights for ground state electrons were calculated using eight band k·p theory at short circuit conditions. With an increase in electric field surrounding the QDs from 5 kV/cm to 50 kV/cm, the effective barrier height of the ground state electrons was reduced from 147 meV to 136 meV, respectively. Thus, the increasing electric field not only exponentially enhances the ground state electron tunneling rate (effectively zero at 5 kV/cm and 7.9 × 10 6s -1 at 50 kV/cm) but also doubles the thermal escape rate (2.2 × 10 11s -1 at 5 kV/cm and 4.1 × 10 11s -1 at 50 kV/cm). Temperature-dependent external quantum efficiency measurements were performed tomore » verify that the increasing electric field decreases the effective barrier height. Additionally, the electric field dependent radiative lifetimes of the ground state were characterized with time-resolved photoluminescence experiments. This study showed that the increasing electric field extended the radiative recombination lifetime in the ground state of the QDs as a consequence of the reduced wave-function overlap between the electrons and holes. The balance of carrier escape and recombination determines the probability of TSPA.« less

Authors:
 [1]; ORCiD logo [1];  [2];  [1]; ORCiD logo [1];  [1];  [3]; ORCiD logo [3]; ORCiD logo [1]
  1. Rochester Inst. of Technology, Rochester, NY (United States). Nanopower Research Lab.
  2. Rochester Inst. of Technology, Rochester, NY (United States). Nanopower Research Lab.; Finisar Corp., Sunnyvale, CA (United States)
  3. Univ. of Toledo, OH (United States). Wright Center for Photovoltaics Innovation and Commercialization (PVIC)
Publication Date:
Research Org.:
Rochester Inst. of Technology, Rochester, NY (United States)
Sponsoring Org.:
USDOE; National Science Foundation (NSF); National Aeronautic and Space Administration (NASA); Air Force Research Lab. (AFRL), Wright-Patterson AFB, OH (United States)
OSTI Identifier:
1465129
Grant/Contract Number:  
FG36-08GO18012; DMR-0955752; NASA SAA3 844; AFRL FA9453-11-C-0253
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 121; Journal Issue: 1; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 77 NANOSCIENCE AND NANOTECHNOLOGY; tunneling; photoluminescence; excited states; III-V semiconductors; quantum dots; solar cells; wetting; ground states; band structure; electric fields

Citation Formats

Dai, Yushuai, Polly, Stephen J., Hellstroem, Staffan, Slocum, Michael A., Bittner, Zachary S., Forbes, David V., Roland, Paul J., Ellingson, Randy J., and Hubbard, Seth M.. Effect of electric field on carrier escape mechanisms in quantum dot intermediate band solar cells. United States: N. p., 2017. Web. doi:10.1063/1.4972958.
Dai, Yushuai, Polly, Stephen J., Hellstroem, Staffan, Slocum, Michael A., Bittner, Zachary S., Forbes, David V., Roland, Paul J., Ellingson, Randy J., & Hubbard, Seth M.. Effect of electric field on carrier escape mechanisms in quantum dot intermediate band solar cells. United States. doi:10.1063/1.4972958.
Dai, Yushuai, Polly, Stephen J., Hellstroem, Staffan, Slocum, Michael A., Bittner, Zachary S., Forbes, David V., Roland, Paul J., Ellingson, Randy J., and Hubbard, Seth M.. Tue . "Effect of electric field on carrier escape mechanisms in quantum dot intermediate band solar cells". United States. doi:10.1063/1.4972958. https://www.osti.gov/servlets/purl/1465129.
@article{osti_1465129,
title = {Effect of electric field on carrier escape mechanisms in quantum dot intermediate band solar cells},
author = {Dai, Yushuai and Polly, Stephen J. and Hellstroem, Staffan and Slocum, Michael A. and Bittner, Zachary S. and Forbes, David V. and Roland, Paul J. and Ellingson, Randy J. and Hubbard, Seth M.},
abstractNote = {Carrier escape and recombination from quantum dot (QD) states reduce the probability of two-step photon absorption (TSPA) by decreasing the available carrier population in the intermediate band (IB). In order to optimize the second photon absorption for future designs of quantum dot embedded intermediate band solar cells, this study combined the results of simulations and experiments to quantify the effect of electric field on the barrier height and the carrier escape from the QDs in InAs/GaAs quantum dot solar cells with five-layer QD superlattices. The electric field dependent effective barrier heights for ground state electrons were calculated using eight band k·p theory at short circuit conditions. With an increase in electric field surrounding the QDs from 5 kV/cm to 50 kV/cm, the effective barrier height of the ground state electrons was reduced from 147 meV to 136 meV, respectively. Thus, the increasing electric field not only exponentially enhances the ground state electron tunneling rate (effectively zero at 5 kV/cm and 7.9 × 106s-1 at 50 kV/cm) but also doubles the thermal escape rate (2.2 × 1011s-1 at 5 kV/cm and 4.1 × 1011s-1 at 50 kV/cm). Temperature-dependent external quantum efficiency measurements were performed to verify that the increasing electric field decreases the effective barrier height. Additionally, the electric field dependent radiative lifetimes of the ground state were characterized with time-resolved photoluminescence experiments. This study showed that the increasing electric field extended the radiative recombination lifetime in the ground state of the QDs as a consequence of the reduced wave-function overlap between the electrons and holes. The balance of carrier escape and recombination determines the probability of TSPA.},
doi = {10.1063/1.4972958},
journal = {Journal of Applied Physics},
number = 1,
volume = 121,
place = {United States},
year = {Tue Jan 03 00:00:00 EST 2017},
month = {Tue Jan 03 00:00:00 EST 2017}
}

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Works referenced in this record:

Band parameters for III–V compound semiconductors and their alloys
journal, June 2001

  • Vurgaftman, I.; Meyer, J. R.; Ram-Mohan, L. R.
  • Journal of Applied Physics, Vol. 89, Issue 11, p. 5815-5875
  • DOI: 10.1063/1.1368156