Electronic properties and low lattice thermal conductivity (κl) of mono-layer (ML) MoS2: FP-LAPW incorporated with spin–orbit coupling (SOC)

Abstract

This paper focuses on the electronic and thermoelectric properties of monolayer MoS₂. Here, we have examined the structure of MoS₂, in which the hole in the center of the hexagonal cage is considered as a void atom, termed 1H-MoS₂. Density functional theory (DFT) employing the generalized gradient approximation (GGA) and spin–orbit coupling (SOC) has been used for all calculations. Incorporation of SOC resulted in a significant change in the profile of the band energy, specifically the splitting of the valence band maximum (VBM) into two sub-bands. The “split-off” energy is found to be ∼20.6 meV. The reduction of the band gap with SOC is a prominent feature at the K–K location in the Brillouin zone. The band gap calculated with the GGA is ∼1.75 eV. However, on implementation of SOC, the GGA band gap was reduced to ∼1.68 eV. The frequency-dependent phonon dispersion curve was obtained to analyse the thermodynamical stability. 1H-MoS₂ is found to be thermodynamically stable with no imaginary frequency. We report a low value of lattice thermal conductivity (κ_l) and low electron effective masses, which are desirable for potential applications in thermoelectric devices.