Understanding Thermal Transport through van der Waals Materials

Vanderbilt University, Nashville TN

Investigators

Abstract

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.