High Thermoelectric Performance of Sb<sub>2</sub>Si<sub>2</sub>Te<sub>6</sub> Monolayers
Wenwu Shi, Ni-Na Ge, Xinzhong Wang, Zhiguo Wang
Abstract
Two-dimensional materials have attracted much attention due to their good thermoelectric (TE) performance caused by the unique density of states at the Fermi energy and low lattice thermal conductivity. Inspired by the high TE performance of bulk Sb2Si2Te6, in this work, the electronic transport, thermal transport, and TE properties of Sb2X2Te6 (X = Si, Ge) monolayers were investigated using density functional theory in combination with the semiclassical Boltzmann transport theory. The results indicate that the Sb2X2Te6 (X = Si, Ge) monolayers are dynamically indirect semiconductors. Sb2Si2Te6 and Sb2Ge2Te6 monolayers have low lattice thermal conductivities of 1.13 and 4.65 W/m·K at room temperature, respectively. High p-type TE performance has been predicted for the Sb2Si2Te6 monolayer with a large figure of merit (ZT) of 4.52–9.62 at a moderate hole concentration of 1.85 × 1013 cm–2 between 300 and 700 K. This study suggests that the Sb2Si2Te6 monolayer might have promising utilization in thermoelectric devices at medium temperature.