Effect of Interfacial Point Defects on Electronic Structure and Thermoelectric Properties of 2d Monolayer Mos2

Abstract

Molybdenum disulfide (MoS2) is considered as a promising economical and non-toxic thermoelectric material duo to its low thermal conductivity and high Seebeck coefficient. However, its power factor is not ideal, which limits its energy conversion efficiency in thermoelectric applications. In this paper, the electronic structure of pure and point-defect MoS2 2D monolayer is studied by using the first principles method and non-equilibrium Green's function (DFT-NEGF). The effects of  atom substitution and vacancy point defect on the thermoelectric properties of MoS2 2D monolayer are also investigated. The result shows that the S-vacancy changes the bandgap by introducing donor and acceptor levels, while the substitution of Se and Te atoms slightly increases the bandgap value. In the case of n-type doping, the ZT value of S atom substituted MoS2 reaches 1.19 at 300K, while Te atom substitution MoS2 has the higher ZT value of almost 2.26 at 800K. The analysis revealed that the thermal conductivity of MoS2 is reduced due to the S-vacancy, while the Se and Te atomic substitution increases the power factor of MoS2. This work provides a new method and theoretical guidance for achieving high performance of thermoelectric devices in energy industry.

Keywords: Transition metal dihalides, 2D MoS2, thermoelectric, ZT, NEGF-DFT