High thermoelectric performance in hexagonal 2D PdTe2 monolayer at room temperature.

Abstract

Motivated by the recent fabrication of hexagonal PdTe2 monolayer, we investigated the thermoelectric properties of the hexagonal and pentagonal PdTe2 structures using two approaches. The pentagonal monolayer has not been synthesized yet. The hexagonal layer had an indirect band gap of 0.17 eV while the pentagonal structure had an indirect bandgap of 1.18 eV. By applying the semi-empirical Wiedemann-Franz law to calculate the electronic thermal conductivity, we found that both hexagonal and pentagonal structures had very high ZT more than 3. However, the Wiedemann-Franz law underestimated the electronic thermal conductivity and this resulted in high ZT. Thus, we employed the Boltzmann transport equation for the electronic thermal conductivity. At high temperature ( > 500 K), the pentagonal PdTe2 structure showed a better thermoelectric performance than the hexagonal structure. However, both structures displayed the same ZT of 0.8 at 300 K. We propose that the hexagonal PdTe2 can be a potential high performance thermoelectric material at room temperature.