Post-Deposition Processing Options for High-Efficiency Sputtered CdS/CdTe Solar Cells

Naba R. Paudel, Matthew Young, Paul J. Roland, Randy J. Ellingson, Yanfa Yan, Alvin D. Compaan

Research output: Contribution to journalArticlepeer-review

41 Scopus Citations


CdCl2 activation near 400°C is known to be critically important for obtaining high efficiency CdS/CdTe solar cells. However, this treatment step behaves differently on high-temperature-grown CdTe than on lower-temperature-grown CdTe layers such as those grown by sputtering. On sputtered films, the post-deposition activation produces grain-boundary passivation, sulfur diffusion into CdTe, and substantial grain growth. Nevertheless, we find the CdCl2 process for sputtered films to be characterized by a single activation energy that we interpret as applying to S diffusion into CdTe. We find this activation energy to hold for CdCl2 treatments from 370 to 440°C. The completed CdS/CdTe solar-cell structures showed somewhat poorer initial performance with activation above 420°C, but, in this case, the cell efficiency increased after accelerated life testing at 85°C, open-circuit biasing and one-sun illumination. With an optimized CdCl2 activation process, the use of oxygenated sputtered CdS, and low-iron soda-lime glass, cell efficiencies of 14.5% were achieved.

Original languageAmerican English
Article number064502
Number of pages7
JournalJournal of Applied Physics
Issue number6
StatePublished - 14 Feb 2014

NREL Publication Number

  • NREL/JA-5200-61948


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