Toward Accelerated Thermoelectric Materials and Process Discovery

Thermoelectric materials have the ability to convert heat energy to electrical power and vice versa. While the thermodynamic upper limit is defined by the Carnot efficiency, the material figure of merit, zT, is far from this theoretical limit, typically limited by a complex interplay of non-equilibrium charge and phonon-scattering. Materials innovation is a slow, arduous process due to the complex correlations between crystal structure, microstructure engineering, and thermoelectric properties. Many physical concepts and materials have been unearthed in this path to discovery, supported ably by innovations in technology over many decades, revealing important material and transport descriptors. In this review, we look back at some case studies of inorganic thermoelectric materials employing a bird’s-eye view of complementary advancements in scientific concepts and technological advancements and conclude that most high values of zT have emerged from developed scientific models fueled by moderately mature technologies. On the basis of this conclusion, we then propose that the recent emergence of data-driven approaches and high-throughput experiments, encompassing synthesis as well as characterization, with machine learning guided inverse design is perfectly suited to provide an accelerated pathway toward the discovery of next-generation thermoelectric materials, potentially providing a feasible alternative source of energy for a sustainable future.

Ady's work on using inertial effective mass as descriptor in the screening of potential TE materials

Effective mass has been touted as an important descriptor in thermoelectric transport. Based on theoretical intuition, some reports demonstrate that low effective mass is preferable in thermoelectrics, while others propose that a large density of states effective mass for high Seebeck is the pathway to better thermoelectric materials. Leveraging on the available data from Materials Project, we present a data-driven conclusion that corroborates the central role of effective mass in high-throughput thermoelectric materials screening. The efficacy of the Fermi surface complexity factor in enhancing power factor is analyzed in relation to the effective mass for a large number of compounds. Here, we show that starting with a low inertial effective mass material, any changes in Fermi surface complexity factor will have a pronounced effect on its thermoelectric power factor and verify this strategy in recently discovered thermoelectric materials. This can be accomplished by employing band engineering using doping, or symmetry distortion, and starting with a base material that intrinsically possesses a low inertial effective mass.