Quasiparticle band structures and optical properties of twisted bilayer MoS₂

¹ School of Science, Hebei University of Technology - Tianjin 300401, PRC
² School of Materials Science and Engineering, Hebei University of Technology - Tianjin 300401, PRC

^(a) jiali@hebut.edu.cn (corresponding author)

Received: 1 June 2021
Accepted: 2 November 2021

Abstract

A twist angle between two adjacent layers is a key approach to adjust the electronic characteristics of the van der Waals bilayer. The main goal of this study is to accurately predict the quasiparticle band structures and optical properties of bilayer MoS₂ with different twist angles , 13.17°, 21.79°, 32.10°, and 60°) by using many-body perturbation G₀W₀ theory and by solving the Bethe-Salpeter equation including excitonic effects on top of the partially G₀W₀ calculation when spin-orbit coupling is included. Results of band structures and optical absorption spectrum show that the band gap and optical gap are sensitive to twist angle. Moreover, the twist angles and spin-orbit coupling can manipulate exciton binding energy. Our results also show that spin-orbit coupling and interlayer coupling (predominantly) induced spin splitting as large as 270 meV at the valence band of K point. This argument implies that twisted bilayer MoS₂ is a powerful system for tuning the photoluminescence emission.