High thermoelectric performance of two-dimensional (PbTe)2 layer

TL;DR

This study demonstrates that the (PbTe)2 layer exhibits high thermoelectric efficiency due to its unique electronic structure and phonon scattering, achieving a ZT of 2.9 at 1000 K.

Contribution

First-principles calculations reveal the high thermoelectric performance of (PbTe)2 layers, highlighting valley degeneracy and van der Waals interactions as key factors.

Findings

Maximum p-type ZT of 2.9 at 1000 K

High electrical conductivity from valley degeneracy

Ultrasmall lattice thermal conductivity due to phonon scattering

Abstract

The electronic, phonon and thermoelectric transport properties of (PbTe)2 layer are systematically investigated by using first-principles pseudopotential method and Boltzmann transport equation. Our calculations demonstrate that there is a valley degeneracy of six for the top valence band, which leads to larger carrier concentration and thus higher electrical conductivity without obvious reduction in the Seebeck coefficient. Moreover, the intrinsic van der Waals interactions between neighboring Pb layers induce additional phonon scattering and thus ultrasmall lattice thermal conductivity. As a consequence, a maximum p-type ZT value of 2.9 can be achieved at 1000 K. Moreover, we find almost identical n- and p-type ZT in the temperature range from 300 K to 800 K.