First-Principles Calculations of Mechanical and Thermoelectric Properties of 2D GeAs: Implications for Flexible Thermoelectric Devices

The development of portable and sustainable power sources is crucial for the advancement of flexible electronics. Thermoelectric devices, made from ductile inorganic thermoelectric materials, present an optimal solution due to their remarkable deformability and their ability to efficiently convert heat into electricity. Nevertheless, the scarcity of these materials underscores the pressing need to further explore the material landscape and to devise strategies that enhance both mechanical and thermoelectric properties. The van der Waals layered semiconductor GeAs has emerged as a ductile thermoelectric material. In this study, we utilized a state-of-the-art first-principles approach to examine the mechanical and thermoelectric properties of GeAs in configurations ranging from monolayer to tetralayer. Our research reveals that as GeAs is thinned to a monolayer, its bendability increases significantly, and its structure becomes stiffer. Moreover, reducing the material to a monolayer results in a 10-fold improvement in the thermoelectric figure of merit, ZT, boosting the power factor and lowering lattice thermal conductivity. At 300 K, ZT reaches a value of one, and at 600 K, it doubles. These findings highlight a promising route to achieve exceptional flexibility and superior thermoelectric conversion efficiency by dimension reduction.