Highly Anisotropic Thermoelectric Properties of Two-Dimensional As₂Te₃

Bulk chalcogenide compounds with chemical formula A2X3 (A = As, Sb, Bi, and X = S, Se, Te) are usually semiconductors, topological insulators, and thermoelectric materials. The layers are stacked together via weak van der Waals interactions and can be exfoliated into thin two-dimensional (2D) layers. Recently, 2D few-layered As2S3 with superior chemical stability was successfully exfoliated in experiments. With a lattice structure to 2D As2S3, monolayer As2Te3 has a heavier atomic mass and a lower lattice thermal conductivity, which is beneficial to the thermoelectric performance. Here, we study the thermoelectric properties of monolayer As2Te3 using ab initio calculations combined with semiclassical Boltzmann transport theory. The optimal figure of merit of 2.36 is achieved for hole doping at 600 K, suggesting that monolayer As2Te3 is a potential competitor among the efficient and anisotropic thermoelectric materials.