Excellent Room-Temperature Thermoelectricity of 2D GeP3: Mexican-Hat-Shaped Band Dispersion and Ultralow Lattice Thermal Conductivity.

Cong Wang,Zhiyuan Xu,Guoying Gao,Ke Xu

doi:10.3390/molecules26216376

Abstract

Although some atomically thin 2D semiconductors have been found to possess good thermoelectric performance due to the quantum confinement effect, most of their behaviors occur at a higher temperature. Searching for promising thermoelectric materials at room temperature is meaningful and challenging. Inspired by the finding of moderate band gap and high carrier mobility in monolayer GeP3, we investigated the thermoelectric properties by using semi-classical Boltzmann transport theory and first-principles calculations. The results show that the room-temperature lattice thermal conductivity of monolayer GeP3 is only 0.43 Wm−1K−1 because of the low group velocity and the strong anharmonic phonon scattering resulting from the disordered phonon vibrations with out-of-plane and in-plane directions. Simultaneously, the Mexican-hat-shaped dispersion and the orbital degeneracy of the valence bands result in a large p-type power factor. Combining this superior power factor with the ultralow lattice thermal conductivity, a high p-type thermoelectric figure of merit of 3.33 is achieved with a moderate carrier concentration at 300 K. The present work highlights the potential applications of 2D GeP3 as an excellent room-temperature thermoelectric material.

Highlights

Thermoelectric (TE) materials, which could convert thermal energy into electric energy, have become more and more important due to their potential in resolving the global warming and the energy dilemma [1,2]
T is the temperature, σ is the electrical conductivity, S is the Seebeck coefficient, and κ is the sum of electronic and phonon thermal conductivity. These TE coefficients are connected by the carrier concentration and will lead to a maximum ZT value at a proper carrier concentration
In the past few years, numerous efforts have suggested that the TE performance of low-dimensional systems could be enhanced compared to their bulk counterparts because of the quantum confinement effect [3,4,5]

Summary

Introduction

Thermoelectric (TE) materials, which could convert thermal energy into electric energy, have become more and more important due to their potential in resolving the global warming and the energy dilemma [1,2]. T is the temperature, σ is the electrical conductivity, S is the Seebeck coefficient, and κ is the sum of electronic and phonon (lattice) thermal conductivity. These TE coefficients are connected by the carrier concentration and will lead to a maximum ZT value at a proper carrier concentration. TE materials with higher ZT values at room temperature will make them commercially viable for the cooling and power generation field [12]. Searching for room-temperature 2D high-performance TE materials is still challenging, because the relatively high lattice thermal conductivity at room temperature hinders the increase of the ZT value. It is necessary to search for promising room-temperature TE materials

Methods

Results

Conclusion