High Thermoelectric Performance of a Novel γ-PbSnX(2) (X = S, Se, Te) Monolayer: Predicted Using First Principles

Two-dimensional (2D) group IV metal chalcogenides are potential candidates for thermoelectric (TE) applications due to their unique structural properties. In this paper, we predicted a 2D monolayer group IV metal chalcogenide semiconductor [Formula: see text]-PbSn(2) (X = S, Se, Te), and first-principles calculations and Boltzmann transport theory were used to study the thermoelectric performance. We found that [Formula: see text]-PbSnX(2) had an ultra-high carrier mobility of up to 4.04 × 10(3) cm(2) V(−1) s(−1), which produced metal-like electrical conductivity. Moreover, [Formula: see text]-PbSn(2) not only has a very high Seebeck coefficient, which leads to a high power factor, but also shows an intrinsically low lattice thermal conductivity of 6–8 W/mK at room temperature. The lower lattice thermal conductivity and high power factors resulted in excellent thermoelectric performance. The [Formula: see text] values of [Formula: see text]-PbSnS(2) and [Formula: see text]-PbSnSe(2) were as high as 2.65 and 2.96 at 900 K, respectively. The result suggests that the [Formula: see text]-PbSnX(2) monolayer is a better candidates for excellent thermoelectric performance.