When, why and where are CdTe/CdS solar cells stable?

K. D. Dobson, Iris Visoly-Fisher, R. Jayakrishnan, K. Gartsman, G. Hodes, David Cahen

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


The role of Cu in CdTe/CdS solar cell instability remains the subject of much debate. The investigation of a range of 'Cu'-contacted CdTe/CdS cells, which had received various thermal stress treatments, is described. Cells that were stressed in air exhibit strong current-voltage (I-V) rollover and junction degradation. No such degradation was observed for 'Cu'-contacted cells that had been stressed in dry-N2 atmosphere. Cu is found to diffuse rapidly through the cell structure during back contact annealing and to accumulate in the CdS layer. With stress, significant levels of Cu dope the grain bulk, producing (with Cl) high resistance, photo-conducting CdS. This behavior is independent of stress atmosphere and is, therefore, unlikely to (initially) be a dominating mechanism for cell degradation. Our results suggest simple air oxidation of the back contact interface to be a likely origin of I-V rollover in CdTe/CdS cells.

Original languageEnglish
Pages (from-to)H8241-H8246
JournalMaterials Research Society Symposium - Proceedings
StatePublished - 2001
Externally publishedYes


This work was supported in part by the US DOE, via the NREL Thin-Film Photovoltaics Partnership Program. We acknowledge D. Rose (FS) and C. Ferekides (USF) for supplying substrates. We thank C. Cyterman (Technion) for SIMS measurements and analysis, L. Burstein (Tel-Aviv University) for AES measurements, H. Cohen and Y. Feldman (WIS) for XPS measurements, and R. Tenne (WIS) for assistance with the PL measurements.

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