Harvesting waste heat as electrical power: Theory-led control of heat transport in thermoelectrics

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Switching to cleaner sources of energy to alleviate global warming is the most important scientific and technological challenge of our time. More than 60 % of the energy used worldwide is wasted as heat from sectors including transportation and industry, representing vast quantities of unnecessary greenhouse gas emissions. Thermoelectric generators improve the efficiency of energy-intensive processes by recovering waste heat as electricity, and viable thermoelectric power is therefore an important part of a secure, sustainable energy strategy. Despite a projected global market of $1bn by 2024, however, large-scale thermoelectric power is currently not feasible due to limited efficiency and the scarcity and toxicity of the materials used.High-performance thermoelectric materials need to be good conductors of electricity and poor conductors of heat. Decades of advances in electronics have enabled materials scientists to reliably optimise the electrical properties of thermoelectrics to improve their performance, but developments are being held back by our poor understanding of heat transport and how to control it. This is an area where materials modelling - calculating and analysing material properties using theory and high-performance computing - has proven to be very successful.The research programme pioneered by this fellowship will cross the boundaries between physics, materials science and chemistry to develop the modelling tools needed for more complete understanding and control of heat transport in materials in general and thermoelectrics in particular. This will be achieved through three complementary aims:(1) Improving our understanding of how doping and alloying - both engineering strategies widely used to optimise thermoelectric performance - affect heat transport. This will allow a set of design rules to be established for choosing the best material modifications to optimise heat transport in tandem with electrical properties, allowing for targeted improvement of new and existing flagship thermoelectric materials. (2) Explaining how the complex ("anharmonic") structural dynamics found in some of the highest-performing thermoelectric materials leads to their desirable ultra-low heat transport, and developing strategies to "design in" this behaviour as a new route to improve thermoelectric performance alongside existing strategies.(3) Developing a novel class of high-performance thermoelectrics based on traditional inorganic materials incorporating small molecules. These "hybrid" materials made headlines for their potential use in high-performance solar cells, and have very recently been shown to have unusually low thermal conductivity, indicating that similar materials may be good candidate thermoelectrics. This last aim will therefore build on the tools and insight developed within the first two to identify and develop these materials into the next generation of high-performance thermoelectrics.This research will establish new routes to improve the performance of current and future thermoelectric materials and will demonstrate the theory-led design of a new class of efficient, cost-effective and sustainable thermoelectric materials suitable for widespread commercialisation. It will put the UK at the forefront of thermoelectric research to provide timely solutions to a critical worldwide challenge and benefit from a growing global market. An improved ability to control heat transport enabled by this programme will also be of immediate benefit to other technologies, yielding more efficient solar cells, better thermal management in batteries and improved power electronics and silicon chips, among others.