# Thermoelectric properties of semimetals

## TL;DR

This study investigates the thermoelectric properties of 18 semimetals, revealing that some can achieve high Seebeck coefficients due to effective mass asymmetry, despite lacking a bandgap.

## Contribution

It introduces a first-principles analysis of semimetals' band structures and identifies effective mass ratio as a key factor for high thermoelectric performance.

## Key findings

- Some semimetals reach Seebeck coefficients up to 200 μV/K.
- Effective mass asymmetry enhances thermoelectric properties.
- Band structure analysis predicts thermoelectric potential in semimetals.

## Abstract

Heavily doped semiconductors are by far the most studied class of materials for thermoelectric applications in the past several decades. They have Seebeck coefficient values which are 2-3 orders of magnitude higher than metals, making them attractive for thermoelectric applications. Semimetals generally demonstrate smaller Seebeck coefficient values due to lack of an energy bandgap. However, when there is a large asymmetry in their electron and hole effective masses, semimetals could have large Seebeck coefficient values. In this work, we study the band structure of a class of 18 semimetals using first principles calculations and calculate their Seebeck coefficient using the linearized Boltzmann equation within the constant relaxation time approximation. We conclude, despite the absence of the band gap, that some semimetals are good thermoelectrics with Seebeck coefficient values reaching up to 200 $\mu$V/K. We analyze the metrics often used to describe thermoelectric properties of materials, and show that the effective mass ratio is a key parameter resulting in high Seebeck coefficient values in semimetals.