Effect of temperature on thermal properties of monolayer MoS2 sheet

Abstract

Influences of temperature on thermal properties of monolayer MoS2 were investigated using first-principles calculations based on the density-functional perturbation theory. The calculated equilibrium vibration properties and Grüneisen parameters γ of monolayer MoS2 are in good agreement with the available experimental and theoretical values. Interestingly, γ of acoustic modes show an evidently asymmetric character due to the sandwiched structure of monolayer MoS2 while γ of optical modes display an approximate symmetry in the first Brillouin zone. Thermal properties analysis shows that temperature has a great effect on Debye temperature θD, isochoric specific heat capacity CV, relaxations time τ, mean free path l, and thermal conductivity κ of monolayer MoS2. With the increasing temperature, θD and CV increase rapidly and then reach saturation, whereas τ and l decrease sharply and then become moderate. The saturation value of θD and CV of monolayer MoS2 is 603K and 17.6cal/cellK, respectively. The κ of monolayer MoS2 illustrates the expected T−1 dependence in the range from 47 to 603K, and it is dominated by longitudinal acoustic (LA) mode which has the maximum value of τ and l. At room temperature, the calculated κ of monolayer MoS2 of 29.2Wm−1K−1 is higher than 1.35Wm−1K−1 that was obtained by Molecular dynamics, but it is in agreement with the experimental value of 34.5±4Wm−1K−1.