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ZnO layers deposited by the ion layer gas reaction on Cu(In,Ga)(S,Se)2 thin film solar cell absorbers—impact of ‘damp-heat’ conditions on the layer properties

  1. M. Bär1,*,
  2. J. Reichardt1,*,
  3. I. Sieber1,
  4. A. Grimm1,
  5. I. Kötschau1,
  6. I. Lauermann1,
  7. S. Sokoll1,
  8. T. P. Niesen2,
  9. M. C. Lux-Steiner1,3,
  10. Ch.-H. Fischer1,3

Article first published online: 29 AUG 2006

DOI: 10.1002/pip.724

Issue

Progress in Photovoltaics: Research and Applications

Progress in Photovoltaics: Research and Applications

Volume 15, Issue 3, pages 187–198, May 2007

Additional Information

How to Cite

Bär, M., Reichardt, J., Sieber, I., Grimm, A., Kötschau, I., Lauermann, I., Sokoll, S., Niesen, T. P., Lux-Steiner, M. C. and Fischer, Ch.-H. (2007), ZnO layers deposited by the ion layer gas reaction on Cu(In,Ga)(S,Se)2 thin film solar cell absorbers—impact of ‘damp-heat’ conditions on the layer properties. Prog. Photovolt: Res. Appl., 15: 187–198. doi: 10.1002/pip.724

Author Information

  1. 1

    Solarenergieforschung, Hahn-Meitner-Institut Berlin, Glienicker Str. 100, D-14109 Berlin, Germany

  2. 2

    Shell Solar GmbH, Otto-Hahn-Ring 6, D-81739 Munich, Germany

  3. 3

    Freie Universität Berlin, D-14195 Berlin, Germany

*Department of Chemistry, University of Nevada, Las Vegas (UNLV), 4505 Maryland Parkway, Las Vegas, NV 89154-4003, USA

Publication History

  1. Issue published online: 22 MAR 2007
  2. Article first published online: 29 AUG 2006
  3. Manuscript Revised: 15 JUN 2006
  4. Manuscript Accepted: 15 JUN 2006
  5. Manuscript Received: 1 MAR 2006

Funded by

  • German BMBF. Grant Number: # 01SF0007
  • BMWA. Grant Number: # 0329889

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Keywords:

  • chalcopyrite thin film solar cell;
  • Cd-free;
  • Damp-Heat

Abstract

Cu(In,Ga)(S,Se)2 (‘CIGSSe’) based solar cells with a ZnO window extension layer (WEL) deposited by the ion layer gas reaction (ILGAR) reach competitive efficiencies compared to corresponding references with CdS buffer and lead to a simplified device structure. The WEL replaces not only the CdS buffer, but also the undoped part of the usually applied rf-sputtered ZnO window bi-layer. The long-term stability of CIGSSe-based solar modules is currently under investigation. In order to pass the respective stability tests, which include exposure to ‘damp-heat’ (DH) conditions (85% relative humidity at 85(C) to accelerate possible aging effects, a good intrinsic material stability is required. In Reference1 it was revealed, that ILGAR-ZnO contains a certain amount of meta-stable hydroxide, which can be directly tuned by the ILGAR process parameters (number of process cycles and process temperature). In order to determine the ILGAR process parameters, which result in intrinsically stable WELs, ILGAR-ZnO/CIGSSe test structures were investigated by means of scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS) before and after a DH-test. It was found that, induced by the DH-conditions, a continuous dehydration of the WELs together with a disintegration of the ILGAR-ZnO layers takes place. This supports an earlier suggested mechanism of a DH-induced degradation by a release of water at the most critical location in a solar cell, at the heterointerface between window and absorber. By a systematic variation of the ILGAR process parameters it was possible to reduce the hydroxide content in the ILGAR-ZnO layers resulting in intrinsically more stable samples. Copyright © 2006 John Wiley & Sons, Ltd.

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