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HL: Fachverband Halbleiterphysik

HL 34: Functional semiconductors for renewable energy solutions II (joint session HL/CPP)

HL 34.3: Vortrag

Dienstag, 17. März 2020, 14:30–14:45, POT 151

Random structure search: Solving the kesterite-stannite
puzzle in (Cu,Ag)₂ZnSnSe₄ solid solution — •Daniel Fritsch¹ and Susan Schorr^1,2 — ¹Department Structure and Dynamics of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany — ²Department of Geosciences, Freie Universität Berlin, Malteserstr. 74−100, 12249 Berlin, Germany

Cu₂ZnSnSe₄ and Ag₂ZnSnSe₄ are both crystallising in the kesterite structure with the structurally similar stannite structure being energetically slightly less favourable. In the solid solution, however, there is experimental evidence that for some intermediate concentrations the stannite structure is energetically favoured. This behaviour is so far not understood.

Here, we’re using density functional theory calculations to shed some light into the structure-property relations in (Cu,Ag)₂ZnSnSe₄. In order to simulate the different concentrations within the solid solution, we’re employing the supercell approach based on the respective end members in the kesterite and stannite structure. The Ag and Cu cations are distributed randomly within the supercell, thereby creating several structure models for the solid solutions for further analysis. All random structure models are geometry optimised employing the recently developed SCAN functional. In order to obtain more reliable electronic and optical properties, selected optimised structures are subjected to single-shot calculations employing the more accurate hybrid functional HSE06.