Rubidium segregation at random grain boundaries in Cu(In,Ga)Se2 absorbers

Schoeppe P, Schoenherr S, Wuerz R, Wisniewski W, Martinez-Criado G, Ritzer M, Ritter K, Ronning C, Schnohr CS (2017)

Publication Type: Journal article

Publication year: 2017

Journal

Nano Energy Elsevier

Book Volume: 42

Pages Range: 307-313

DOI: 10.1016/j.nanoen.2017.10.063

Abstract

Solar cells based on Cu(In,Ga)Se2 absorbers are the most efficient ones among all thin film photovoltaics. The current world record efficiency was attained by applying a rubidium fluoride (RbF) post deposition treatment (PDT) to the absorber. However, it is still not clear why the introduced Rb improves the solar cell performance. In order to investigate the beneficial effect of Rb, a Cu(In,Ga)Se2 absorber was grown on a Mo coated alkali free substrate and subjected to a RbF PDT. This pure RbF PDT without any additional alkalis from the substrate leads to a strong increase in solar cell efficiency. A thin cross sectional lamella was cut out of the layer stack and investigated via a combination of electron microscopy and high resolution synchrotron based methods. This combinatory approach provides clear indications of the origin of the beneficial effect of Rb. It is evident that Rb agglomerates at detrimental random high angle grain boundaries and dislocation cores, where it likely passivates defects, which would otherwise lead to a recombination of carriers. In contrast, Rb does not agglomerate at benign Σ3 twin boundaries. Additionally, Rb segregates at the interface between the absorber and the MoSe2 layer.

Involved external institutions

Friedrich-Schiller-Universität Jena DE Germany (DE) Zentrum für Sonnenenergie- und Wasserstoff-Forschung (ZSW) DE Germany (DE) Spanish National Research Council / Consejo Superior de Investigaciones Científicas (CSIC) ES Spain (ES)

How to cite

APA:

Schoeppe, P., Schoenherr, S., Wuerz, R., Wisniewski, W., Martinez-Criado, G., Ritzer, M.,... Schnohr, C.S. (2017). Rubidium segregation at random grain boundaries in Cu(In,Ga)Se2 absorbers. Nano Energy, 42, 307-313. https://doi.org/10.1016/j.nanoen.2017.10.063

MLA:

Schoeppe, Philipp, et al. "Rubidium segregation at random grain boundaries in Cu(In,Ga)Se2 absorbers." Nano Energy 42 (2017): 307-313.

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