Dresden 2020 – wissenschaftliches Programm
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CPP 52.3: 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 Schorr1,2 — 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.