Metallic Thermoelectrics: High Thermoelectric Performance through Tuning of Electronic Scattering

Thermoelectric (TE) materials directly transform thermal into electrical energy and vice versa, making them promising for a plethora of applications in refrigeration or power generation. However, state-of-the-art semiconductors in the focus of current research did not make the leap into broad applications due to low power density and poor mechanical properties. Metallic systems would be superior in this regard, but remained largely neglected by the TE community over the past decades due to their small TE effect.This fundamental research project focuses on realizing high TE performance in metals via tuning of electronic interband scattering – an innovative enhancement principle cardinally different from those applied so far in semiconductors. Using this paradigm, we want to realize- unprecedented TE power factors- metallic TE with superior functional properties from highly abundant, cheap materials- tight control of energy-dependent electronic transport by scattering off topological flat bandsDespite enormous efforts for decades, largely focusing on a reduction of thermal conductivity in semiconductors, these intriguing research issues remain unsolved calling for a novel concept.We tackle these issues by focusing on metals, where the lattice thermal conductivity is irrelevant compared to the electronic contribution (Wiedemann-Franz law), thus confining the multi-parameter optimization problem to a sole enhancement of the Seebeck coefficient S. The latter we achieve by selectively reducing the mobility of holes (or electronic carriers) by interband scattering from localized states, leveraged by tuning of electronic bandwidth and geometrical frustration – concepts introduced from correlated electron physics. Promoted by the PI’s versatile expertise in studying charge transport in solids, METHEL explores high-performance metallic TE by the synergistic combination of synthesis, spectroscopy, microscopy and high-throughput computational materials screening.