Generation of electricity from heat via the Seebeck effect is silent, environmentally friendly and requires no moving parts. Waste heat from automobile exhausts and industrial manufacturing processes could be used to generate electricity economically, provided materials with a high thermoelectric efficiency (characterised by a high dimensionless thermoelectric figure of merit ZT) could be identified. Conversely, Peltier cooling using such materials would have applications ranging from on-chip cooling of CMOS-based devices to home refrigerators.
Currently-available thermoelectric materials are semiconductors, typically based in Bi, Pb, Te or Se, which are toxic, expensive and have limited efficiency, which constrains them to niche applications. Wide scale applications of thermoelectricity require new low-cost materials with much higher thermoelectric efficiency.
The ability to manipulate quantum interference (QI) in molecules creates the potential for high-performance and sustainable materials with unprecedented thermoelectric efficiencies. To deliver the next breakthrough, QuIET will exploit QI at the single-molecule level and then translate this enhanced functionality to technologically-relevant thin-film materials and devices above room temperature. We will establish the feasibility of using QI in molecular junctions at room temperature to enhance their Seebeck coefficient, and combine this with mechanical tuning of molecules and electrode-molecule couplings to minimise their phonon thermal conductance. This will be achieved by combining theoretical predictions of their electronic and vibrational properties with our ability to design and synthesize new molecules and to measure their Seebeck coefficient and thermal conductance. Furthermore, we will establish strategies to exploit this QI functionality in many-molecule thin films providing a basis for the design of practical devices and new materials to solve the optimization challenge of combining high efficiency with low cost and toxicity.
The objectives of QuIET are to:
1. Develop single-molecule junctions with high thermopower by taking advantage of QI.
2. Enhance thermoelectric efficiency of single-molecule junctions by minimising the phonon contribution to thermal conductance.
3. Create self-assembled monolayers (SAMs) that preserve the high thermopower and low thermal conductance obtained in single-molecule junctions, and further enhance their thermoelectric properties via intermolecular interactions.
4. Identify implementation routes of scalable thermoelectric devices based on molecular junctions.
To deliver these objectives, QuIET will bring together the multidisciplinary expertise of leading scientists in molecular synthesis, experimental quantum transport in nanosystems, and modelling and theoretical calculations in the nanoscale.
