Topological Insulators for Thermoelectrics

The rising energy demand and environmental concerns from conventional cooling systems, including those pertaining to refrigeration and air conditioning, poses significant challenges. Distributed thermoelectric cooling offers a viable solution, yet the low power conversion efficiencies necessitate new search and design strategies for improved thermoelectrics. Here, we show that topological insulators are a promising class of materials for next-generation thermoelectrics. We find that the band inversion strength is a key property of topological insulators connected to warping of the bulk electronic structure and, as a result, fundamentally influences the thermoelectric performance. The band inversion strength can be tuned by modulating orbital interactions through e.g. alloying or strain engineering. We evaluate the band inversion strengths of a large set of topological insulators, resulting in the prediction that NaCaBi is a particularly promising thermoelectric candidate. The study offers unique avenues for discovering and designing thermoelectric materials by capitalizing on the electronic structure topology.