Cu2ZnSnS4 thin-film solar cell absorbers illuminated by soft x-rays


In view of the complexity of thin-film solar cells, which are comprised of a multitude of layers, interfaces, surfaces, elements, impurities, etc., it is crucial to characterize and understand the chemical and electronic structure of these components. Because of the high complexity of the Cu2ZnSn(S,Se)4 compound semiconductor absorber material alone, this is particularly true for kesterite-based devices. Hence, this paper reviews our recent progress in the characterization of Cu2ZnSnS4 (CZTS) thin films. It is demonstrated that a combination of different soft x-ray spectroscopies is an extraordinarily powerful method for illuminating the chemical and electronic material characteristics from many different perspectives, ultimately resulting in a comprehensive picture of these properties. The focus of the article will be on secondary impurity phases, electronic structure, native oxidation, and the CZTS surface composition.

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R.G. Wilks and M. Bär acknowledge the financial support by the Impuls- und Vernetzungsfonds of the Helmholtz-Association (VH-NG-423). The ALS is funded by the Department of Energy, Basic Energy Sciences, Contract No. DE-AC02-05CH11231. Furthermore, the authors thank J. Paier and G. Kresse for making their calculated DOS data15 available in electronic form.

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Bär, M., Schubert, BA., Marsen, B. et al. Cu2ZnSnS4 thin-film solar cell absorbers illuminated by soft x-rays. Journal of Materials Research 27, 1097–1104 (2012).

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