Abstract
As the demand for high-quality solar-cell feedstock exceeds supply and drives prices upwards, cheaper but dirtier alternative feedstock materials are being developed1,2,3. Successful use of these alternative feedstocks requires that one rigorously control the deleterious effects of the more abundant metallic impurities. In this study, we demonstrate how metal nanodefect engineering can be used to reduce the electrical activity of metallic impurities, resulting in dramatic enhancements of performance even in heavily contaminated solar-cell material. Highly sensitive synchrotron-based measurements4,5 directly confirm that the spatial and size distributions of metal nanodefects regulate the minority-carrier diffusion length, a key parameter for determining the actual performance of solar-cell devices. By engineering the distributions of metal-impurity nanodefects in a controlled fashion, the minority-carrier diffusion length can be increased by up to a factor of four, indicating that the use of lower-quality feedstocks with proper controls may be a viable alternative to producing cost-effective solar cells.
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Acknowledgements
Collaboration with M. Heuer, S. Fakra, M. D. Pickett, R. Jonczyk, T. F. Ciszek, K. O. Dijon, J. Isenberg, W. Warta, R. Schindler and G. Willeke is gratefully appreciated. This work was funded by National Renewable Energy Laboratory subcontract AAT-2-31605-03. Use of the Advanced Photon Source and of the Advanced Light Source is supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract Numbers W-31-109-ENG-38 and DEAC03-76SF00098, respectively.
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Buonassisi, T., Istratov, A., Marcus, M. et al. Engineering metal-impurity nanodefects for low-cost solar cells. Nature Mater 4, 676–679 (2005). https://doi.org/10.1038/nmat1457
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DOI: https://doi.org/10.1038/nmat1457
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