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Kerfless exfoliated thin crystalline Si wafers with Al metallization layers for solar cells

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Abstract

We report on a kerfless exfoliation approach to further reduce the costs of crystalline silicon photovoltaics making use of evaporated Al as a double functional layer. The Al serves as the stress inducing element to drive the exfoliation process and can be maintained as a rear contacting layer in the solar cell after exfoliation. The 50–70 µm thick exfoliated Si layers show effective minority carrier lifetimes around 180 µs with diffusion lengths of 10 times the layer thickness. We analyze the thermo-mechanical properties of the Al layer by x-ray diffraction analysis and investigate its influence on the exfoliation process. We evaluate the approach for the implementation into solar cell production by determining processing limits and estimating cost advantages of a possible solar cell design route. The Al–Si bilayers are mechanically stable under processing conditions and exhibit a moderate cost savings potential of 3–36% compared to other c-Si cell concepts.

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ACKNOWLEDGMENTS

The authors thank Alwina Knorr, Rene Berger, Daniel Münster, Frank Heinemeyer, and David Sylla for valuable help with the sample preparation and Jan-Hendrik Petermann and Chistopher Kranz for fruitful discussions on cell concepts and the cost model. This work was supported by the Federal Ministry for Environment, Nature Conservation, and Nuclear Safety and the Federal Ministry for Economic Affairs and Energy under the contract FKZ 0325461 (MEMO), and by the state of Lower Saxony.

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Authors and Affiliations

  1. Department of Photovoltaics, Institute for Solar Energy Research Hamelin (ISFH), D-31860, Emmerthal, Germany

    Raphael Niepelt, Jan Hensen, Verena Steckenreiter, Rolf Brendel & Sarah Kajari-Schöder

  2. Institut für Festkörperphysik, Leibniz Universität Hannover, D-30167, Hannover, Germany

    Rolf Brendel

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  1. Raphael Niepelt
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Correspondence to Raphael Niepelt.

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Niepelt, R., Hensen, J., Steckenreiter, V. et al. Kerfless exfoliated thin crystalline Si wafers with Al metallization layers for solar cells. Journal of Materials Research 30, 3227–3240 (2015). https://doi.org/10.1557/jmr.2015.309

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