ECN publication
Sensitivity of crystalline silicon solar cells to metal impurities
Published by: Publication date:
ECN Solar Energy 5-9-2011
ECN report number: Document type:
ECN-M--11-014 Conference Paper
Number of pages: Full text:
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The sensitivity to impurities of the solar cell conversion efficiency is reported for a state of the art (i.e. 18%) and advance device architecture (i.e. 23%). The data are based on the experimental results obtained in the CrystalClear project for the state of the art cell process and extrapolated to a device with excellent front and rear surface passivation. Both device structures are not assumed to work in low injection level as several studies assumed before but real operating conditions are considered. This is a fundamental difference with the past and required for modeling future high efficiency devices. In general advanced devices will be more sensitive to the impurity content than the state of the art cell design. This effect is partly compensated by reducing the base thickness. In high efficiency devices, a large reduction of the impurity impact is visible for impurities with large capture cross section ratio like Fe which reduces its relative difference in comparison with e.g. Cr which has a small capture cross section ratio.

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