Hostname: page-component-586b7cd67f-vdxz6 Total loading time: 0 Render date: 2024-11-25T15:23:13.175Z Has data issue: false hasContentIssue false
  • English
  • Français

Role of Surface Band Gap Widening in Cu(In, Ga)(Se, S)2 Thin-Films for the Photovoltaic Performance of ZnO/CdS/Cu(In, Ga)(Se, S)2 Heterojunction Solar Cells

Published online by Cambridge University Press:  01 February 2011

U. Rau  and
M. Turcu
U. Rau
Affiliation:
Institute of Physical Electronics, University of Stuttgart, Pfaffenwaldring 47, 70569 Stuttgart, Germany
M. Turcu
Affiliation:
Institute of Physical Electronics, University of Stuttgart, Pfaffenwaldring 47, 70569 Stuttgart, Germany
Get access

Abstract

Numerical simulations are used to investigate the role of the Cu-poor surface defect layer on Cu(In, Ga)Se2 thin-films for the photovoltaic performance of ZnO/CdS/Cu(In, Ga)Se2 heterojunction solar cells. We model the surface layer either as a material which is n-type doped, or as a material which is type-inverted due to Fermi-level pinning by donor-like defects at the interface with CdS. We further assume a band gap widening of this layer with respect to the Cu(In, Ga)Se2 bulk. This feature turns out to represent the key quality of the Cu(In, Ga)Se2 surface as it prevents recombination at the absorber/CdS buffer interface. Whether the type inversion results from n-type doping or from Fermi-level pinning is only of minor importance as long as the surface layer does not imply a too large number of excess defects in its bulk or at its interface with the normal absorber. With increasing number of those defects an n-type layer proofs to be less sensitive to material deterioration when compared to the type-inversion by Fermi-level pinning. For wide gap chalcopyrite solar cells the internal valence band offset between the surface layer and the chalcopyrite appears equally vital for the device efficiency. However, the unfavorable band-offsets of the ZnO/CdS/Cu(In, Ga)Se2 heterojunction limit the device efficiency because of the deterioration of the fill factor.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 763: Symposium B – Compound Semiconductor Photovoltaics , 2003 , B8.8
Copyright
Copyright © Materials Research Society 2003

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Schmid, D., Ruckh, M., Grunwald, F., and Schock, H. W., J. Appl. Phys. 73, 2902 (1993).Google Scholar
2. Morkel, M., Weinhardt, L., B. Lohmüller, Heske, C., Umbach, E., Riedl, W., Zweigart, S., and Karg, F., Appl. Phys. Lett. 79, 4482 (2001).Google Scholar
3. Ramanathan, K., Noufi, R., Granata, J., Webb, J., and Keane, J., Sol. Energy Materials & Solar Cells 55, 15 (1998).Google Scholar
4. Sugiyama, T., Chaisitsak, S., Yamada, A., Konagai, M., Kudriavtsev, Y., Godines, A., Villegas, A., and Asomoza, R., Jpn. J. Appl. Phys., Part 1 39, 4816 (2000).Google Scholar
5. Jiang, C.-S., Hasoon, F. S., Moutinho, H. R., Al-Thani, H. A., Romero, M. J., and Al-Jassim, M. M., Appl. Phys. Lett. 82, 127 (2003).Google Scholar
6. Herberholz, R., Rau, U., Schock, H. W., Haalboom, T., Gödecke, T., Ernst, F., Beilharz, C., Benz, K. W., and Cahen, D., Eur. Phys. J. AP 6, 131 (1999).Google Scholar
7. Rau, U., Braunger, D., Herberholz, R., Schock, H.-W., Guillemoles, J.-F., Kronik, L., and Cahen, D., J. Appl. Phys. 86, 497 (1999).Google Scholar
8. Huang, C. H., Li, S. S., and Anderson, T. J., Proceedings of the 29th IEEE Photovoltaic Specialists Conference (IEEE, New York, 2002), p. 748.Google Scholar
9. Turcu, M. and Rau, U., J. Phys. Chem. Solids, in print.Google Scholar
10. Dullweber, T., Hanna, G., Rau, U., and Schock, H. W., Sol. Energy Materials & Solar Cells 67, 145 (2001).Google Scholar
11. Niemegeers, A. and Burgelman, M., Proceedings of the 25th IEEE Photovoltaic Specialists Conference (IEEE, New York, 1996), p. 901.Google Scholar
12. Rau, U., Schmidt, M., Jasenek, A., Hanna, G., and Schock, H. W., Sol. Energy Materials & Solar Cells 67, 137 (2001).Google Scholar
13. Hanna, G., Jasenek, A., Rau, U., and Schock, H. W., Thin Solid Films 387, 71 (2001).Google Scholar
14. Klenk, R., Thin Solid Films 387, 135 (2001).Google Scholar
15. Turcu, M., Pakma, O., and Rau, U., Appl. Phys. Lett. 80, 2598 (2002).Google Scholar
16. Yan, Y., Jones, K. M., AbuShama, J., Al-Jassim, M. M., and Noufi, R., Mater. Res. Soc. Symp. Proc. 668, H6.10.1 (2001).Google Scholar
17. Jasenek, A., Rau, U., Nadenau, V., and Schock, H. W., J. Appl. Phys. 87, 594 (2000).Google Scholar