Remarkable suppression of thermal conductivity by point defects in MoS2 nanoribbons

By applying non-equilibrium molecular dynamics simulation, we investigate the effect of point defects on thermal conductivity of MoS2 nanoribbons, such as sulfur vacancies (V5) and oxygen substitutions to sulfur (So). It is found that both Vs and So can significantly reduce thermal conductivity of monolayer M0S2 nanoribbons, but the suppression of thermal conductivity by vacancies is stronger than that by substitutions. For armchair MoS2 nanoribbon of 41.1 nm length and 4.4 nm width, when defect density is only 1.5%, the reduction of thermal conductivity at room temperature by Vs defects and So defects is 42.3% and 35.1%, respectively. We perform the vibrational eigenmodes analysis and find that the strong localization of phonons of all modes by defects results in the severe reduction of thermal conductivity of MoS2 nanoribbons. Further spectra analysis reveals that the localized modes are located in the sites of defects and the sites around defects, due to the change of force constant at these sites. Our findings are helpful for understanding and tuning the thermal conductivity of MoS2 nanoribbons by defect engineering. (C) 2015 Elsevier B.V. All rights reserved.