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Reduced Thermal Transport in the Graphene/MoS2/Graphene Heterostructure: A Comparison with Freestanding Monolayers
Langmuir ( IF 3.9 ) Pub Date : 2018-02-10 00:00:00 , DOI: 10.1021/acs.langmuir.7b03974
Srilok Srinivasan 1 , Ganesh Balasubramanian 2
Affiliation  

The thermal conductivity of the graphene-encapsulated MoS2 (graphene/MoS2/graphene) van der Waals heterostructure is determined along the armchair and zigzag directions with different twist angles between the layers using molecular dynamics (MD) simulations. The differences in the predictions relative to those of the monolayers are analyzed using the phonon power spectrum and phonon lifetimes obtained by spectral energy density analysis. The thermal conductivity of the heterostructure is predominantly isotropic. The out-of-plane phonons of graphene are suppressed because of the interaction between the adjacent layers that results in the reduced phonon lifetime and thermal conductivity relative to monolayer graphene. The occurrence of an additional nonzero phonon branch at the Γ point in the phonon dispersion curves of the heterostructure corresponds to the breathing modes resulting from stacking of the layers in the heterostructure. The thermal sheet conductance of the heterostructure being an order of magnitude larger than that of monolayer MoS2, this van der Waals material is potentially suitable for efficient thermal packaging of photoelectronic devices. The interfacial thermal conductance of the graphene/MoS2 bilayer as a function of the heat flow direction shows weak thermal rectification.

中文翻译:

石墨烯/ MoS 2 /石墨烯异质结构中的热传递降低:与独立式单分子膜的比较

石墨烯包裹的MoS 2(石墨烯/ MoS 2使用分子动力学(MD)模拟沿着层之间的不同扭转角确定扶手椅和Z字形方向上的范德华异质结构。使用声子功率谱和通过光谱能量密度分析获得的声子寿命来分析相对于单层预测的差异。异质结构的热导率主要是各向同性的。石墨烯的平面外声子被抑制,因为相邻层之间的相互作用导致相对于单层石墨烯缩短的声子寿命和导热性。在异质结构的声子色散曲线的Γ点处出现一个额外的非零声子分支,对应于异质结构中各层的堆叠所产生的呼吸模式。异质结构的导热片电导比单层MoS的导热片电导大一个数量级如图2所示,该范德华材料潜在地适合于光电器件的有效热包装。石墨烯/ MoS 2双层的界面热导随热流方向的变化表现出较弱的热精馏。
更新日期:2018-02-10
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