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Limiting Light Escape Angle in Silicon Photovoltaics: Ideal and Realistic Cells

Kosten, Emily D. and Newman, Bonna K. and Lloyd, John V. and Polman, Albert and Atwater, Harry A. (2015) Limiting Light Escape Angle in Silicon Photovoltaics: Ideal and Realistic Cells. IEEE Journal of Photovoltaics, 5 (1). pp. 61-69. ISSN 2156-3381. doi:10.1109/JPHOTOV.2014.2360566.

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Restricting the light escape angle within a solar cell significantly enhances light trapping, resulting in potentially higher efficiency in thinner cells. Using an improved detailed balance model for silicon and neglecting diffuse light, we calculate an efficiency gain of 3%_(abs) for an ideal Si cell of 3-µm thickness and the escape angle restricted to 2.767° under AM1.5 direct illumination. Applying the model to current high-efficiency cell technologies, we find that a heterojunction-type device with better surface and contact passivation is better suited to escape angle restriction than a homojunction type device. In these more realistic cell models, we also find that there is little benefit gained by restricting the escape angle to less than 10°. The benefits of combining moderate escape angle restriction with low to moderate concentration offers further efficiency gains. Finally, we consider two potential structures for escape angle restriction: a narrowband graded index optical multilayer and a broadband ray optical structure. The broadband structure, which provides greater angle restriction, allows for higher efficiencies and much thinner cells than the narrowband structure.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle
Polman, Albert0000-0002-0685-3886
Atwater, Harry A.0000-0001-9435-0201
Additional Information:© 2014 IEEE. Manuscript received June 29, 2014; revised September 11, 2014; accepted September 17, 2014. Date of publication October 22, 2014; date of current version December 18, 2014. The work of E. D. Kosten and H. A. Atwater was supported by the Light–Matter Interactions Energy Frontier Research Center: an EFRC program of the Office of Science, United States Department of Energy, under Grant DE-SC0001293. The work of E. D. Kosten was supported by the Resnick Sustainability Institute Graduate Fellowship. The work of J. V. Lloyd was supported by the DOW Chemical Company. Work at the Center for Nanophotonics at AMOLF is part of the research program of FOM, which is financially supported by NWO. It is also supported by the European Research Council. E. D. Kosten and B. K. Newman contributed equally to this work. The authors would like to thank M. Sheldon, H. Emmer, and W. Sinke for insightful discussions and advice on the manuscript.
Group:Resnick Sustainability Institute
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0001293
Resnick Sustainability InstituteUNSPECIFIED
Dow Chemical CompanyUNSPECIFIED
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)UNSPECIFIED
European Research Council (ERC)UNSPECIFIED
Subject Keywords:Nanostructures, photovoltaic cells, silicon
Issue or Number:1
Record Number:CaltechAUTHORS:20150109-081928470
Persistent URL:
Official Citation:Kosten, E.D.; Newman, B.K.; Lloyd, J.V.; Polman, A.; Atwater, H.A., "Limiting Light Escape Angle in Silicon Photovoltaics: Ideal and Realistic Cells," Photovoltaics, IEEE Journal of , vol.5, no.1, pp.61,69, Jan. 2015 doi: 10.1109/JPHOTOV.2014.2360566 URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53450
Deposited By: Tony Diaz
Deposited On:09 Jan 2015 22:28
Last Modified:10 Nov 2021 20:02

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