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Proceedings Paper

A novel approach for correlating capacitance data with performance during thin-film device stress studies
Author(s): Rebekah L. Graham; Laura A. Clark; David S. Albin
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Paper Abstract

A new data mining algorithm was developed to identify the strongest correlations between capacitance data (measured between -1.5 V and +0.49 V) and first- and second-level performance metrics (efficiency [η%], open-circuit voltage [VOC], short-circuit current density [JSC], and fill-factor [FF]) during the stress testing of voltage-stabilized CdS/CdTe devices. When considering only correlations between first- and second-level metrics, 96.5% of the observed variation in η% was attributed to FF. The overall decrease in VOC after 1,000 hours of open-circuit, light-soak stress at 60°C was about -1.5%. As determined by our algorithm, the most consistent correlation existing between FF and third-level metric capacitance data at all stages during stress testing was between FF and the apparent CdTe acceptor density (Na) calculated at a voltage of +0.49 V during forward voltage scans. Since the contribution of back-contact capacitance to total capacitance increases with increasing positive voltage, this result suggests that FF degradation is associated with decreases in Na near the CdTe/back contact interface. Also of interest, it appears that capacitance data at these higher voltages appears to more accurately fit the one-sided abrupt junction model.

Paper Details

Date Published: 13 September 2011
PDF: 8 pages
Proc. SPIE 8112, Reliability of Photovoltaic Cells, Modules, Components, and Systems IV, 81120V (13 September 2011); doi: 10.1117/12.896648
Show Author Affiliations
Rebekah L. Graham, National Renewable Energy Lab. (United States)
Laura A. Clark, PrimeStar Solar (United States)
David S. Albin, National Renewable Energy Lab. (United States)


Published in SPIE Proceedings Vol. 8112:
Reliability of Photovoltaic Cells, Modules, Components, and Systems IV
Neelkanth G. Dhere; John H. Wohlgemuth; Kevin W. Lynn, Editor(s)

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