Material Property Changes in Defects Caused by Reverse Bias Exposure of CIGS Solar Cells

Klaas Bakker, Hanna Nilsson Åhman, Kees Aantjes, Nicolas Barreau, Arthur Weeber, Mirjam Theelen

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)
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Abstract

Partial shading of Cu(In,Ga)Se2 modules can lead to the formation of reverse bias induced wormlike defects. These wormlike defects act as local shunts and permanently decrease module output. A good understanding of the formation and propagation mechanisms of these defects is needed in order to mitigate the negative effects, or to prevent these defects from forming. In this article, wormlike defects were formed on small nonencapsulated cells by exposing them to reverse bias conditions. Scanning electron microscopy-energy-dispersive X-ray spectroscopy measurements showed a rearrangement of elements: Indium, gallium, and copper were replaced by cadmium, whereas selenium was replaced by sulfur in the area around the defect. Moreover, additional electronic-defect levels were found in that area with spectrally resolved photoluminescence spectroscopy. Based on the material changes in the area close to the wormlike defects, a propagation mechanism is proposed. The model assumes a chemical reaction as the driving force for propagation instead of melting because of ohmic heating.

Original languageEnglish
Article number8851179
Pages (from-to)1868-1872
Number of pages5
JournalIEEE Journal of Photovoltaics
Volume9
Issue number6
DOIs
Publication statusPublished - 2019

Keywords

  • Cadmium
  • electric breakdown
  • photolumine-scence (PL)
  • photovoltaic (PV) cells
  • reliability
  • thin film devices

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