Exploiting chemical bonding principles to design high-performance thermoelectric materials

Thermoelectric materials offer unique opportunities to convert otherwise wasted thermal energy into useful electrical energy. Many of the traditional thermoelectric materials, such as bismuth telluride and lead telluride, contain scarce and toxic elements. This has motivated the search for new high-performance materials containing readily-available and environmentally-less-damaging elements. Numerous advances in the development of high-performance thermoelectric materials exploit fundamental chemical-bonding principles. Much of the thermoelectric literature lies at the interface of chemistry, physics and materials science. In this Review, progress in the design of high-performance materials is discussed in terms of ideas that are familiar in chemistry. This includes the influence of concepts such as bonding heterogeneity, covalency, polarizability, lone pairs and different bonding models, including multi-centre, metallic and iono-covalent archetypes. In this way, we seek to present aspects of this diverse field of research in terms that are accessible to the chemistry community. Many of the advances in high-performance thermoelectric materials can be related to fundamental chemical-bonding principles. Application of concepts including bonding models, lone pairs, bonding heterogeneity, multi-centre bonding and polarizability to the development of advanced thermoelectric materials are discussed here.