Analytical Model And Simulation Study Of Phonon Weak Coupling In Stacked Graphene

With the development of modern technology and people’s pursuit of high-quality informationized life,electronic chips have been as small as a few nanometers,and more than 50% of the damage is caused by ultra-heat.Therefore,researching the heat transport mechanism of nanomaterials is of great significance to thermal management.Graphene is considered to be an excellent heat dissipation material in modern electronic devices due to its excellent thermal conductivity.There are many interfaces caused by the stacking of twodimensional materials in the heat dissipation materials,which reduce the thermal conductivity of the heat dissipation materials.Therefore,the mechanism analysis and optimization study of the heat conduction of the stacked graphene structure are very important to solve the heat dissipation problem.Phonon coupling affects heat transfer,and a basic understanding of phonon coupling is required for the thermal management of low-dimensional materials.Based on the Boltzmann transport equation,this paper firstly proposes phonon weak coupling model(PWCM),which are divided into "implicit coupling" and "explicit coupling",corresponding to the coupling in internal structure and the coupling between two structures,respectively.In the explicit coupling,the theoretical analysis models of the overlapped interface and van der Waals heterojunction interface are further derived.Molecular dynamics simulation is used to calculate the interfaces of overlapped graphene nanoribbons and graphene-molybdenum disulfide van der Waals heterojunction.The results show that the interfacial thermal resistance between the overlapped graphene nanoribbons is greatly reduced by bonding the carbon chains.The PWCM is used to analyze and explain the two-dimensional heat transport mechanism in the overlapped interface.When overlapped graphene nanoribbons are bonded by only one carbon chain,the interface thermal resistance is reduced by an order of magnitude.And as the number of carbon chains increases,the rate of decrease of the interface thermal resistance gradually slows down,which can be explained by the theoretical relationship based on the PWCM.In addition,the comparison between the PWCM and the traditional simplified model confirms the accuracy of the PWCM in calculating the interface thermal resistance.Meanwhile,for the graphenemolybdenum disulfide van der Waals heterojunction,the theoretical temperature distribution curve derived by PWCM is consistent with the temperature distribution obtained by the simulation,which further theoretically reveals the heat transfer mechanism of the van der Waals heterojunction interface.This paper combines theoretical models and molecular dynamics simulation to conduct in-depth research and analysis on the interfacial heat conduction mechanism and influencing factors of stacked graphene structures.This work not only deepens the understanding of the interfacial heat transfer mechanism,but also provides a practical method for improving the interface heat transfer and effective thermal management.