Two-Dimensional Sn₂Te₆As₂ as a Promising Thermoelectric Material: Insights from Density Functional and Boltzmann...

The efficient conversion of waste heat into electricity is a key challenge in energy sustainability, driving the search for novel thermoelectric materials with enhanced performance. In this work, we investigate the thermoelectric properties of the two-dimensional (2D) material Sn₂Te₆As₂, a theoretically predicted compound identified through machine-learning-assisted materials discovery, using first-principles calculations combined with Boltzmann transport theory. Our results reveal an exceptionally low lattice thermal conductivity of κ^latt = 0.24 W/mK at room temperature, which is crucial in improving thermoelectric efficiency by limiting heat dissipation. Additionally, the electronic transport properties, evaluated under the relaxation time approximation (RTA), confirm the isotropic nature of charge transport, ensuring balanced electrical conduction in different crystallographic directions. The figure of merit (ZT) reaches 0.69 for holes and 0.61 for electrons at 300 K, increasing to a peak of 0.80 and 0.79, respectively, at 600 K. The combination of ultralow lattice thermal conductivity, favorable charge transport characteristics, and an optimal operating temperature range suggests that Sn₂Te₆As₂ could be an effective thermoelectric material. These properties make it particularly promising for applications in waste heat recovery and midtemperature energy conversion. These findings offer valuable insights into the fundamental properties of this material and establish a solid foundation for future theoretical and experimental studies aimed at optimizing its thermoelectric performance.