Solid-liquid structure of Cu₂S: Theoretical acanthite-like model for electronic and transport properties investigations.

Cu₂S has long been studied for its potential applications in the field of photovoltaic solar cells and, most recently, thermoelectricity (TE) [1]. The interesting properties of this material are mainly driven by the liquid-like behavior of the Cu atoms, which is also a barrier that confuses us in determining their atomic positions and electronic properties [2]. In this work, using a theoretical model called the acanthite-like phase, we confirm the appearance of electronic structure with the indirect bandgap as observed experimentally before [3]. The formation of point defects and their influence on the conductive properties are also discussed. Finally, the use of the electron-phonon scattering approximation allows us to estimate the electron energy relaxation time, thereby reproducing the reasonable results of transport property compared to experimental observation. Therefore, demonstrating that the acanthite-like model is ideally suitable and can be used for computational design of TE material related to the low-temperature phase of Cu₂S.

[1] D. S. Nkemeni, Z. Yang, S. Lou, G. Li, and S. Zhou, J. Alloys Compd. 878, 160128 (2021).

[2] P. Lukashev, W. R. L. Lambrecht, T. Kotani, and M. van Schilfgaarde, Phys. Rev. B 76, 195202 (2007).

[3] L. D. Partain, P. S. McLeod, J. A. Duisman, T. M. Peterson, D. E. Sawyer, and C. S. Dean, J. Appl. Phys. 54, 6708 (1983).