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Chemical Control of Heating and Cooling in Molecular Junctions: Optimizing Function and Stability

Final Report Summary - CHEMHEAT (Chemical Control of Heating and Cooling in Molecular Junctions: Optimizing Function and Stability)

In the project CHEMHEAT we studied single molecules bound between metallic electrodes with 3 key objectives:
• Developing chemical control of (current induced) local heating in molecular junctions.
• Developing chemical control of heat dissipation in molecular junctions.
• Design of optimal thermoelectric materials.
While traditional chemistry is replete with knowledge of how chemical structure influences physical properties, nanotechnology has resulted in new types of physical measurements and now we need to build this same understanding for properties like conductance, current induced heating, heat dissipation and thermoelectric response. Our approach is theoretical/computational, combining the use of numerical calculations and model system calculations in the spirit of physical organic chemistry. That is, we understand that there is a huge degree of complexity in the junctions we study, but we can make progress if we hold all that is complex constant and simply vary the structure of the molecule in a clearly controlled fashion. With the knowledge of how trends evolve across families of molecules we can begin to unravel how chemical structure controls function.
The project brought together a team of PhD students and postdocs from Europe, USA and China to work together on these three challenges. We had great success in all three challenge areas and have worked to disseminate our results to the scientific community. We have published papers in peer-reviewed journals, made oral and poster presentations at international meetings and hosted a workshop on interference effects in molecular electron transport.
Progress in interdisciplinary topics, like molecular electronics, is very much supported by collaboration across traditional departmental boundaries. While our team was located in the Department of Chemistry, we benefitted from our collaborations both within the University of Copenhagen (with experimental chemists and theoretical physicists) and outside (researchers in theoretical physicists at the Technical University of Denmark, electrical engineering at the University of Rome “Tor Vergata”, applied physics at Columbia University, theoretical chemistry at Cornell University, physics at Delft University, theoretical physics at the Max Planck Institute for Polymer Research Mainz).