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High Open-Circuit Voltage in Silicon Heterojunction Solar Cells

Published online by Cambridge University Press:  01 February 2011

Qi Wang ,
Matt R. Page ,
Eugene Iwancizko ,
Yueqin Xu ,
Lorenzo Roybal ,
Russell Bauer ,
Dean Levi ,
Yanfa Yan ,
Tihu Wang  and
Howard M. Branz
Qi Wang
Affiliation:
qi_wang@nrel.gov, NREL, EDMD, 1617 Cole Blvd, Golden, CO, 80410, United States
Matt R. Page
Affiliation:
Matt_page@nrel.gov, National Renewable Eenergy Laboratory, EDMD, Golden, CO, 80410, United States
Eugene Iwancizko
Affiliation:
eugence_iwancizko@nrel.gov, National Renewable Eenergy Laboratory, EDMD, Golden, CO, 80410, United States
Yueqin Xu
Affiliation:
yueqin_xu@nrel.gov, National Renewable Eenergy Laboratory, EDMD, Golden, CO, 80410, United States
Lorenzo Roybal
Affiliation:
Lorenzo_Roybal@nrel.gov, National Renewable Eenergy Laboratory, EDMD, Golden, CO, 80410, United States
Russell Bauer
Affiliation:
russell_bauer@nrel.gov, National Renewable Eenergy Laboratory, EDMD, Golden, CO, 80410, United States
Dean Levi
Affiliation:
Dean_levi@nrel.gov, National Renewable Eenergy Laboratory, EDMD, Golden, CO, 80410, United States
Yanfa Yan
Affiliation:
yanfa_yan@nrel.gov, National Renewable Eenergy Laboratory, EDMD, Golden, CO, 80410, United States
Tihu Wang
Affiliation:
tihu_wang@nrel.gov, Suntech Power, Wuxi, N/A, China, People's Republic of
Howard M. Branz
Affiliation:
howard_branz@nrel.gov, National Renewable Eenergy Laboratory, EDMD, Golden, CO, 80410, United States
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Abstract

High open-circuit voltage (Voc) silicon heterojunction (SHJ) solar cells are fabricated in double-heterojunction a-Si:H/c-Si/a-Si:H structures using low temperature (<225°C) hydrogenated amorphous silicon (a-Si:H) contacts deposited by hot-wire chemical vapor deposition (HWCVD). On p-type c-Si float-zone wafers, we used an amorphous n/i contact to the top surface and an i/p contact to the back surface to obtain a Voc of 667 mV in a 1 cm2 cell with an efficiency of 18.2%. This is the best reported p-type SHJ voltage. In our labs, it improves over the 652 mV cell obtained with a front amorphous n/i heterojunction emitter and a high-temperature alloyed Al back-surface-field contact. On n-type c-Si float-zone wafers, we used an a Si:H (p/i) front emitter and an a-Si:H (i/n) back contact to achieve a Voc of 691 mV on 1 cm2 cell. Though not as high as the 730 mV reported by Sanyo on n-wafers, this is the highest reported Voc for SHJ c-Si cells processed by the HWCVD technique. We found that effective c-Si surface cleaning and a double-heterojunction are keys to obtaining high Voc. Transmission electron microscopy reveals that high Voc cells require an abrupt interface from c-Si to a-Si:H. If the transition from the base wafer to the a-Si:H incorporates either microcrystalline or epitaxial Si at c Si interface, a low Voc will result. Lifetime measurement shows that the back-surface-recombination velocity (BSRV) can be reduced to ~15 cm/s through a-Si:H passivation. Amorphous silicon heterojunction layers on crystalline wafers thus combine low-surface recombination velocity with excellent carrier extraction.

Keywords

photovoltaicSithin film
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 989: Symposium A – Amorphous and Polycrystalline Thin-Film Silicon Science and Technology-2007 , 2007 , 0989-A03-04
Copyright
Copyright © Materials Research Society 2007

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References

1 Taguchi, M., Kawamoto, K., Tsuge, S., Baba, T., Sakata, H., Morizane, M., Uchihashi, K., Nakamura, N., Kiyama, S., and Oota, O., Prog. PV Res. Appl, 8: p. 503, 2000.Google Scholar
2 Wang, T.H., Iwaniczko, E., Page, M.R., Levi, D.H., Yan, Y., Yelundur, V., Branz, H.M., Rohatgi, A., and Wang, Q.. IEEE.Proceedings of the 31st IEEE Photovoltaic Specialists Conference p. 955, 2005.Google Scholar
3 Wang, T.H., Page, M.R., Iwaniczko, E., Xu, Y.Q., Yan, Y.F., Roybal, L., Levi, D., Bauer, R., Branz, H.M., and Wang, Q.. WIP-Renewable Energies. 21st European Photovoltaic Solar Energy Conference p. 781, 2006.Google Scholar
4 Page, M.R., Iwaniczko, E., Wang, Q., Levi, D.H., Yan, Y., Branz, H.M., Yelundur, V., Rohatgi, A., and Wang, T.H.. National Renewable Energy Laboratory. 14th Workshop on Crystalline Silicon Solar Cells & Modules:Materials and Processes p. 246, 2004.Google Scholar
5 Page, M.R., Iwaniczko, E., Xu, Y., Wang, Q., Yan, Y., Roybal, L., Branz, H.M., and Wang, T. H.. the 4th World Conference on Photovoltaic Energy Conversion (WCPEC-4) p. 6, 2006.Google Scholar
6 Wang, T.H., Page, M.R., Iwaniczko, E., Xu, Y.Q., Yan, Y.F., Roybal, L., Levi, D., Bauer, R., Branz, H.M., and Wang, Q.. MRS. 910: Mat. Res. Soc. Proc. p. 731, 2006.Google Scholar
7 Schaper, M., Schmidt, J., Plagwitz, H., and Brendel, R., Prog. Photovolt: Res. Appl, 13: p. 381, 2005.Google Scholar
8 Rostan, P.J., Rau, U., Nguyen, V.X., Kirchartz, T., Schubert, M.B., and Werner, J.H.. Technical Digest of the 15th International Photovoltaic Science & Engineering Conference p. 214, 2005.Google Scholar
9 Yan, Y., Page, M., Wang, T. H., Al-Jassim, M.M., Branz, H. M., and Wang, Q., Appl. Phys. Lett., 88: p.3, 2006.Google Scholar
10 Wolf, Stefaan De and Kondo, M., Appl. Phys. Lett., 90: p.042111, 2007.Google Scholar