Impact of copper on light-induced degradation in Czochralski silicon PERC solar cells

C. Modanese, Mt Wagner, F. Wolny, A. Oehlke, H. S. Laine, A. Inglese, H. Vahlman, M. Yli-Koski, H. Savin*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

8 Citations (Scopus)
29 Downloads (Pure)

Abstract

Both multicrystalline and Czochralski (Cz) silicon substrates are known to suffer from various mechanisms of light-induced degradation (LID), including copper-related LID (Cu-LID). Past studies on Cu-LID have mostly been performed on unprocessed wafers, omitting the impact of the solar cell process on the copper distribution. Here, we carefully contaminate Cz-substrates of different quality with different amounts of copper and process the substrates into complete industrial Cz-Si PERC solar cells, reaching a comprehensive mapping of the impact of Cu-LID for the PV industry. The results show that both the copper contamination level and Cz crystal quality are critical factors affecting the extent of Cu-LID. Most importantly, we show that copper can result in significant concentrations in the bulk of the finished PERC cells after being exposed to only trace surface contamination. Consequently, even a small local copper contamination area (~ 3–4 cm2) is sufficient to induce strong LID in the full-sized (156 × 156 mm2) cell parameters, resulting e.g. in ~7% relative efficiency loss during light soaking. The corresponding short circuit current density decreases by up to a factor of two in the contaminated areas.

Original languageEnglish
Pages (from-to)373-377
Number of pages5
JournalSolar Energy Materials and Solar Cells
Volume186
DOIs
Publication statusPublished - 1 Nov 2018
MoE publication typeA1 Journal article-refereed

Keywords

  • Cell efficiency
  • Copper
  • Czochralski silicon
  • LID imaging
  • Light-induced degradation
  • PERC

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