Recent Progress on Thermal Conduction of Graphene

Abstract

With the irreversible trend of miniaturization and the pursuit of a high power density in electronic devices, heat dissipation has become crucial for designing nextgeneration electronic products. Graphene, which has the highest thermal conductivity among all discovered solid materials, has attracted attention from both academia and the industry. As a two-dimensional material with atom-scale thickness, graphene is suitable for investigating the phonon transport behavior at reduced dimensions. The mass production technique of graphene makes it a promising material for thermal management in consumer electronics, information technology, medical devices, and new energy automobiles. In this review, we summarize the recent progress on the thermal conduction of graphene. In the first part, we introduce the thermal conductivity measurement methods for graphene, including the optothermal Raman method, suspended-pad method, and time-domain thermoreflectance (TDTR) method. The thermal measurement of graphene with high accuracy is key to understanding the heat transfer mechanism of graphene; however, it is still a significant challenge. Despite the development of measurement methods, the thermal measurement of suspended single-layer graphene is limited by the graphene transfer technique, estimation of the thermal contact resistance, sensitivity to the in-plane thermal conductivity in the thermal model, and other factors. In the second part, we discuss the theoretical study of the thermal conductivity of graphene via first principle calculations and molecular dynamics simulation. The "selection rule" of phonon scattering explains the thickness-dependent thermal conductivity of few-layer graphene, and the understanding of the contribution of phonon modes to the thermal conductivity of graphene has been updated recently by taking multiple-phonon scattering into consideration. The size effect on the thermal conductivity of graphene is discussed in this section for a better understanding of the phonon transport behavior of graphene. In the third part, we conclude with the thermal management applications of graphene, including a highly thermally conductive graphene film, graphene fiber, and graphene-enhanced thermal interface materials. For graphene films, which are the pioneering thermal management applications in industrial use, we focus on the challenge of fabricating highly thermally conductive graphene films with large thicknesses and propose possible technical methods. For graphene-enhanced thermal interface materials, we summarize the main factors affecting the thermal properties and discuss the tradeoff between the high thermal conductivity of graphene flakes and the dispersibility of graphene in the polymer matrix. It was demonstrated that a 3D thermal conductive network is essential for efficient heat dissipation in graphene-based composites. Finally, a summary of opportunities and challenges in the thermal study of graphene is presented at the end of the review. Research on the thermal properties of graphene has made imm...

Recent progress of 2-dimensional layered thermoelectric materials

“…拉曼法、电子束自加热法、TDTR 等等 [22] 。本文对二维材料的热导率测量方法 进行简单介绍，对该系列测试方法及原理详见其他综述文章 [7,22,[36][37][38] ，本文着重 介绍能同时适用于二维材料热导率与电学性质的测试方法。 2.2 悬空热桥法 悬空热桥法在 2003 年被 Shi 等人提出 [39] ，是测量微纳尺度热传导的主要方 法之一，它具有着较高的测量精度和适中的操作难度，随着微纳尺度加工技术 的不断发展，其也被越来越广泛地被应用。悬空热桥法由四根悬臂和两个加热 电极组成 [22,26] ，如图 2c 所示。它可以同时测量样品的热导率、电导率和塞贝克 系数，测试样品可以利用干法转移、湿法转移、pick-up 方法 [40][41][42] [27,43,44] 。H 型测量方法有着高的电测量精度、可选择激光 都是对热电性能不利的 [45] 。因此对于二维热电材料的研究，大多数都集中于半 导体材料。由 Goldsmid−Sharp 可知，可以从禁带宽度预测材料塞贝克最大值 [46,47] ， max max…”

“…在 2013 年，Xu 等人研究了单层悬空石墨烯热导率随样品长度的变化关系 [59] ， 发现由于石墨烯横向声子平均自由程在 10 μm 左右，随着样品长度不断减小， 会导致声子散射的增加，热导率会不断降低到 500 W/m•K 以下。如图 3b 是一系 列石墨烯热导率与样品长度关系的汇总 [38] 。虽然利用上述方法对石墨烯热导率 进行了抑制，但这离理想热电的数值还相差较大，因此进一步降低石墨烯热导 率仍是未来研究的方向之一。还有很多方法可以降低石墨烯热导率进而提升其 热电性能，这里就不再一一介绍，有兴趣的读者可以关注石墨烯热传导的一些 综述文章 [22,[36][37][38] 。 石墨烯电学性能也十分突出，具有着高的电导率和塞贝克系数，且其可以 在n型和p型区域内都有着很高的功率因数，方便研究者通过掺杂的方式在两个 区域对其进行研究。2009年，研究者首次利用场效应晶体管的方法同时测量了…”

2D layered BP/InSe and BP/Janus In2SeX (X = S or Te) type-II van der Waals heterostructures for photovoltaics: insight from first-principles calculations

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Temperature effects on thermal transport at the graphene-liquid interface

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