Impact of copper on light-induced degradation in Czochralski silicon PERC solar cells
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2018-11-01
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Language
en
Pages
5
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Solar Energy Materials and Solar Cells, Volume 186, pp. 373-377
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.Description
| openaire: EC/FP7/307315/EU//SOLARX
Keywords
Cell efficiency, Copper, Czochralski silicon, LID imaging, Light-induced degradation, PERC
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Citation
Modanese, C, Wagner, M, Wolny, F, Oehlke, A, Laine, H S, Inglese, A, Vahlman, H, Yli-Koski, M & Savin, H 2018, 'Impact of copper on light-induced degradation in Czochralski silicon PERC solar cells', Solar Energy Materials and Solar Cells, vol. 186, pp. 373-377. https://doi.org/10.1016/j.solmat.2018.07.006