Layered Tl2O: a model thermoelectric material

Abstract

Two-dimensional materials with a higher figure of merit ZT would be desirable in energy conversion techniques. High power factor and low lattice thermal conductivity are two essential indicators of high ZT and it is important to explore the limits of what can be achieved in two-dimensions including realistic material parameters. Using first principles calculations and Boltzmann transport theory, the thermoelectric transport properties of single-, bi- and tri-layer Tl₂O are analyzed. The carrier relaxation time is calculated based on electron–phonon scattering. It is found that tri-layer Tl₂O exhibits a high power factor. With the analysis of the thermal conductivity from the lattice and electrons, we find that single layer p-type Tl₂O has a high ZT of about 2 at 300 K.