Regensburg 2019 – wissenschaftliches Programm
CPP 25.31: Poster
Dienstag, 2. April 2019, 14:00–16:00, Poster B1
Phase Stability Simulation of Copper Chalkogenide Nanoparticles From First Principles — •Alkit Beqiraj, Ahed Abbousie, Andreas Taubert, and Thomnas Körzdörfer — Uni Potsdam, Am Neuen Palais 10, 14469 Potsdam
Being p-type semiconductors, CuS based nanoparticles demonstrate a large variety of potential applications in optoelectronic devices or energy technology. F.i. CuS nanoparticles can be used as an efficient hole collection layer in an organic solar cell. The CuSx nanoparticles can be synthesized at room temperature using an ionic liquid precursor. This synthesis, however, is very challenging, since even minor variation of the synthesis conditions can change the bias of the reaction, leading to the unexpected precipitation and phase transformation of different oxidative species of copper sulfides. Especially one polymorph of covellite (CuS), i.e., the semiconductor digenit (Cu1.8S), is of particular interest, as it is a frequently encountered byproduct of the synthesis. In order to understand the phase transformation, the chemical parameters, and the nature of the synthesis we carried out DFT calculations. To predict phase stability, vibrational contributions to the free energy were calculated within the harmonic supercell approach. From these calculations, we predict ab initio thermodynamic alloy phase diagrams. From these results, it is possible to analyze which parameters influence the phase evolution of digenit and covellite. Overall, our theoretical results are in a good agreement with the experimental observations and, thus, can be used to intentionally manipulate the experimental conditions in favor of the desired polymorph.