Hybrid-Density Functional Theory Study on Band Structures of Tetradymite-Bi2Te3, Sb2Te3, Bi2Se3, and Sb2Se3 Thermoelectric Materials

TL;DR

This study uses hybrid-density functional theory to analyze the band structures of key thermoelectric materials, revealing limitations in predictive accuracy related to interlayer distances and functional sensitivity.

Contribution

It demonstrates that hybrid-DFT does not significantly improve band gap predictions over standard DFT for tetradymite thermoelectric materials.

Findings

Hybrid-DFT results are highly sensitive to exchange functional choice.

Hybrid-DFT does not outperform DFT in predicting band gaps.

Poor interlayer distance predictions affect band structure accuracy.

Abstract

The low energy band structure near the band gap determines the electrical performance of thermoelectric materials. Here, by using the hybrid-density functional theory (hybrid-DFT) calculations, we calculate the low energy band structure of Bi2Te3, Sb2Te3, Bi2Se3 and Sb2Se3 in tetradymite phase. We find that the band structure characteristics are very sensitive the selection of the exchange energy functional. The predictability of the band gaps and band degeneracies is not enhanced in hybrid-DFT calculations, as compared to DFT calculations. The poor prediction of low energy band structures is originated from the poor prediction of interlayer distances and the high structure sensitivity on the band gap. We conclude that the hybrid DFT calculations are not superior to DFT calculations when predicting band structures of tetradymite Bi2Te3, Sb2Te3, Bi2Se3 and Sb2Se3 thermoelectric materials.