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| Home > Publications database > Composition-dependent nanostructure of $\mathrm{Cu(In,Ga)Se_{2}}$ powders and thin films |
| Home > Publications database > Composition-dependent nanostructure of $\mathrm{Cu(In,Ga)Se_{2}}$ powders and thin films |
| Poster | PUBDB-2014-04034 |
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2014
Abstract: Both the Ga gradient and the Cu content strongly influence the electrical properties and thus the conversion efficiency of Cu(In,Ga)Se2 thin film solar cells. However, the material composition also affects the atomic arrangements on the nanometer scale which were shown to deviate significantly from the average long-range crystallographic structure [1,2]. The anion displacement, in particular, depends sensitively on the kind of neighboring cations [1] and has a significant influence on the material bandgap [2,3]. We have therefore used extended X-ray absorption fine structure spectroscopy to compare the atomic-scale structural parameters of Cu(In,Ga)Se2 powders and polycrystalline thin films with varying composition. No difference in the two sample types is observed for the average Cu-Se, Ga-Se and In-Se bond lengths which are nearly independent of both the Ga and the Cu content. This demonstrates the strong tendency towards bond length conservation typical for tetrahedrally coordinated semiconductors. In contrast, the bond length variation is significantly smaller in the thin films than in the powders, particularly for Cu-poor material. This difference in the nanostructure is proposed to originate from differences in the preparation conditions, most prominently from the different history of Cu composition.
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