Effect of Electron-Phonon Interaction and Ionized Impurity Scattering on the Room Temperature Thermoelectric Properties of Bulk $MoSe_2$

TL;DR

This study uses first-principles calculations to analyze how electron-phonon and impurity interactions influence the thermoelectric properties of bulk MoSe2 at room temperature, highlighting anisotropic mobility and optimizing power factor.

Contribution

It provides a detailed first-principles analysis of the effects of electron-phonon and impurity scattering on thermoelectric properties of bulk MoSe2, including anisotropic mobility and the impact of van der Waals interactions.

Findings

Cross-plane mobility is two orders of magnitude smaller than in-plane.

In-plane thermoelectric power factor peaks at 20 μWcm^{-1}K^{-2} at 1.5x10^{20} cm^{-3}.

Seebeck coefficient is mainly determined by band structure with minimal effect from relaxation times.

Abstract

We study the thermoelectric properties of bulk $MoSe_2$ within relaxation time approximation including electron-phonon and ionized impurity interactions using first-principles calculations at room temperatures. The anisotropy of this two-dimensional layered metal dichalcogenide is studied by calculations of electron mobility in the cross-plane and the in-plane directions. We show that the cross-plane mobility is two orders of magnitude smaller than the in-plane one. The inclusion of van der Waals interactions further lowers the carrier mobility in the cross-plane direction but minimally affects the in-plane one. The results for in-plane electrical mobility and conductivity are in close agreement with experimentally reported values indicating the accuracy of the calculations. The Seebeck coefficient calculations show that this coefficient is primarily dictated by the band structure. The details of relaxation times and inclusion of van der Waals interactions only slightly change the Seebeck coefficient. The in-plane thermoelectric power factor reaches a maximum value of 20 $\mu Wcm^{-1}K^{-2}$ at a carrier concentration of $1.5x10^{20}$ $cm^{-3}$ at 300K.