Regensburg 2010 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 39: Topical Session Photovoltaic Materials III
MM 39.4: Talk
Wednesday, March 24, 2010, 15:30–15:45, H4
Neutron diffraction investigations of kesterites: cation order and disorder — •Susan Schorr1, Michael Tovar2, Sergej Levcenco3, Alexander Napetrov3, and Ernest Arushanov3 — 1Free University Berlin, Institute of Geological Sciences, Germany — 2Helmholtz Zentrum Berlin für Materialien und Energie, Germany — 3Academy of Sciences of Moldova Republic, Institute of Applied Physics, Chisinau, Moldova
The quaternary chalcogenides Cu2ZnSnS4 and Cu2ZnSnSe4 have newly attracted attention as possible absorber materials in thin film solar cells.
They crystallize in the kesterite type (space group I4) or stannite type structure (space group I42m), which are described as an ordered distribution of the cations on different structural sites. Cation disorder may cause site defects and hence influences the electronic properties of the material. Thus the degree of cation order/disorder plays a crucial role and was therefor in the focus of the presented investigations. A differentiation between the isoelectronic cations Cu+ and Zn2+ is not possible using X-ray diffraction due to their similar scattering power. But their neutron scattering lengths are different, thus neutron diffraction opens the possibility to determine the cation distribution in these compounds. A simultaneous Rietveld analysis of neutron and X-ray powder diffraction data revealed that in dependence on the thermal history of the samples cation disorder appears. The correlation trend between cation order/disorder and the sample growth method (solid state synthesis, Bridgemann method) will be discussed.
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