Honeycomb-like puckered PbTe monolayer: A promising n-type thermoelectric material with ultralow lattice thermal conductivity

Inspired by the superior thermoelectric performance of two-dimensional (2D) materials, the electrical transport and thermoelectric properties of honeycomb-like puckered PbTe monolayer were theoretically evaluated using the first-principles calculations and the semiclassical Boltzmann transport theory. The puckered PbTe monolayer is a direct gap semiconductor with wide bandgap of 2.251 eV within Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional in combination with spin-orbital coupling (SOC) effect. Further analysis of formation energy, elastic constant, and ab initio molecular dynamics (AIMD) simulation prove the thermodynamic, mechanical and thermal stabilities of PbTe monolayer. The low thermal transport, small phonon group velocity, large Grüneisen parameters, and short phonon relaxation time greatly suppress the phonon transport and lead to low lattice thermal conductivity of ∼0.75 and ∼0.79 W/m K along the armchair and zigzag directions at 900 K, respectively. An optimal ZT = ~1.55 at the carrier concentration of 3.94 × 1012 cm−2 is obtained for PbTe monolayer along zigzag direction at 900 K, which demonstrates the great advantages of honeycomb-like puckered PbTe monolayer as promising n-type thermoelectric material. Our present results would not only provide fundamental understanding of thermoelectric transport in honeycomb-like puckered PbTe monolayer, but also shed some light on the theoretical design of low dimensional PbTe-layered nanomaterials in thermoelectric applications.