Understanding Thermal Transport through van der Waals Materials

货车德瓦耳斯（vdW）晶体显示出许多新颖和理想的性质，例如沿沿着不同方向的高度各向异性的电和热输运能力。 据预测，这些材料可以彻底改变柔性电子设备，光伏能源转换器和生物医学设备。 然而，必须首先彻底了解它们的电学和热学性质。 该项目探讨了不同的因素如何影响通过各种vdW纳米线的热传输。 将进行系统的研究，以了解能量载体如何相互作用，以及这些纳米线的热特性如何随着线尺寸的变化而变化，这将为调整具有改进性能的新型器件的材料特性提供新的见解。vdW晶体的热性质对于基于vdW材料的器件的正常功能是极其重要的;然而，对vdW晶体中的热输运机制的理解还远未完成。 该项目通过单个准一维vdW纳米线测量电子和声子输运，以深入了解基本问题，包括如何正确构建vdW晶体的声子色散，维度转变与链内/链间键合的相对强度之间的关系，以及不同的声子散射机制，特别是电子-声子耦合，如何影响vdW材料的热输运。 三种不同的VDW晶体，Ta 2 Pd 3Se 8，NbSe 3，TaSe 3，这代表了一个广泛的VDW相互作用强度和电性能，检查解剖这些参数的影响。 该项目产生了vdW材料中迫切需要的热传输知识，这对各种应用至关重要。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

van der Waals (vdW) crystals demonstrate many novel and desirable properties such as highly anisotropic electrical and thermal transport capabilities along different directions. It has been projected that these materials could revolutionize flexible electronic devices, photovoltaic energy converters, and biomedical devices. However, a thorough understanding of their electrical and thermal properties has to be achieved first. This project explores how different factors influence thermal transport through various vdW nanowires. Systematic studies will be conducted to understand how energy carriers interact with each other and how thermal properties of these nanowires vary as the wire size changes, which will provide new insights into tuning the materials properties for novel devices with improved performance. Thermal properties of vdW crystals are extremely important for the proper function of vdW materials-based devices; however, the understanding of thermal transport mechanisms in vdW crystals is far from complete. This project measures electron and phonon transport through individual quasi-one-dimensional vdW nanowires to provide insights into fundamental questions including how to correctly construct phonon dispersion for vdW crystals, what is the relation between dimensionality transition and the relative strength of intra-chain/inter-chain bonding, and how different phonon scattering mechanisms, especially electron-phonon coupling, affect thermal transport in vdW materials. Three different kinds of vdW crystals, Ta2Pd3Se8, NbSe3, and TaSe3, which represent a wide spectrum of vdW interaction strength and electrical properties, is examined to dissect the effects of these parameters. The project generates the urgently-needed knowledge of thermal transport in vdW materials that is critical for various applications.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.