Thermal conductivity of monolayer MoS₂, MoSe₂, and WS₂: interplay of mass effect, interatomic bonding and anharmonicity

Abstract

Phonons are essential for understanding the thermal properties in monolayer transition metal dichalcogenides, which limit their thermal performance for potential applications. We investigate the lattice dynamics and thermodynamic properties of MoS 2 , MoSe 2 , and WS 2 by first principles calculations. The obtained phonon frequencies and thermal conductivities agree well with the measurements. Our results show that the thermal conductivity of MoS 2 is highest among the three materials due to its much lower average atomic mass. We also discuss the competition between mass effect, interatomic bonding and anharmonic vibrations in determining the thermal conductivity of WS 2 . Strong covalent W-S bonding and low anharmonicity in WS 2 are found to be crucial in understanding its much higher thermal conductivity compared to MoSe 2 .

Determining the Optimized Interlayer Separation Distance in Vertical Stacked 2D WS2:hBN:MoS2 Heterostructures for Exciton Energy Transfer

“…The amount of strain is evaluated by carefully examining the photon energy in the PL spectra under similar excitation conditions, which is 0.6% for the WS 2 in MoS 2 :hBN:WS 2 VLHs and 0.12% for the MoS 2 in WS 2 :hBN:MoS 2 VLHs . The monolayer WS 2 is more strained than the MoS 2 due to the higher growth temperature of WS 2 and their similar calculated linear thermal expansion coefficients relative to the SiO 2 /Si substrate, while the cooling procedures in CVD and characterization parameters are kept identical. The presence of strain causes band gap modification, which will change the relative band offsets between WS 2 and MoS 2 monolayers and in turn the details of the type II heterostructure .…”

Synthesis of WS2/CNT hybrid nanoparticles for fabrication of hybrid aluminum matrix nanocomposite

“…Lahiri et al [56,57] confirmed this mechanism in aluminum matrix. In this study, thermal expansion coefficient for carbon nanotubes, tungsten sulfide and aluminum are equal to 2×10 −5 K −1 , 14.8×10 −6 K −1 , 24×10 −6 K −1 respectively [58,59]. There is a significant difference between the thermal expansion coefficient of the reinforcements and matrix, which causes the thermal stress in the reinforcement interface area in matrix and around the reinforcement themselves.…”

The electronic, optical, and thermodynamic properties of borophene from first-principles calculations

“…The calculated Debye temperature for borophene is 863.86 K, which is higher than that of monolayer MoS 2 (262.3 K) 33 and black phosphorene (500 K) 53 , but lower than that of graphene (2,300 K) 54 . Concerning thermal vibrations, the Debye temperature is a measure of the temperature above which all modes begin to be excited 55 , which will further affect the heat transport in borophene.…”

“…The bond length of B 1 -B 1 and B 2 -B 2 bonds along the a direction is 1.613 Å, and that of B 1 -B 2 bonds is 1.879 Å. In contrast to 2D honeycomb materials [31][32][33][34] , borophene has a highly anisotropic crystal structure with space group Pmmn 9 .…”