Controlling Thermal Transport in Hybrid, 2D, Thermoelectric Devices from the Bottom-Up

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Controlling Thermal Transport in Hybrid, 2-Dimensional Materials from the Bottom-UpThe development of highly-efficient thermoelectric materials, which can directly convert wasted heat into electrical power, has emerged as one of the ultimate goals of nanoscale science and technology. Utilizing the unique properties of nanostructured materials has resulted in incredible progress in the advancement of thermoelectric materials. However, despite these advances, it is still difficult to accurately predict how the properties of these complex systems will evolve as the size scales, or how modifying the component materials will affect the final system properties. One of the primary reasons for this difficulty is that improving the thermoelectric properties of a system requires simultaneous control of three properties: the electrical conductivity, the thermopower (Seebeck coefficient), and the thermal conductivity. This project will use hybrid, 2-dimensional (2D), molecule-nanoparticle materials as a model system for exploring the thermal transport properties of nanostructured thermoelectric materials. This is a unique materials system where the properties of individual components can be measured, controlled, and characterized, and then embedded into the hybrid material so that the complex interplay between the components can be determined as the system scales-up or as the components are modified. By examining the thermal and mechanical properties of the molecular components, and the effects of these properties on thermal transport of the hybrid materials, this project aims to develop a set of design rules for controlling the thermal transport properties of hybrid molecule-nanoparticle thermoelectric devices. This knowledge can then be leveraged into a more general understanding of the properties that govern heat transport in nanostructured materials, so that control of the thermal transport properties of these systems can be designed in from the atomic-level up. This project will focus on understanding and controlling the thermal transport properties of the hybrid materials by: i) examining the role of the vibrational density of states of the molecular substituents on the thermal transport properties; ii) studying how molecular rigidity and nanoparticle mass and composition influence heat transport; iii) investigating the evolution of the thermal transport properties of the arrays as the system size scales; and iv) examining the interplay between these properties to enable the design of nanostructured systems with desired properties. This investigation will provide unprecedented information about the interplay between the atomic-scale thermal properties of component materials and the properties of integrated, hybrid materials across a range of size-scales. Using a combination of single-molecule spectroscopic techniques (Inelastic Electron Tunneling Spectroscopy, and electromechanical ?alpha? spectroscopy), modification of nanoparticle size and composition, and lithographic control of feature sizes will reveal how both the molecular and nanoparticle properties dictate the thermal transport properties of 2D, hybrid, molecule-nanoparticle arrays. These studies will provide crucial information about which of these properties dominate heat transport in nanostructured materials, the relationships between them, and how this interplay evolves as the device size scales. This systematic series of experiments will allow for a new understanding of the principles that dictate thermal transport in nanostructured materials, and will enable the passive control of thermal transport to be designed into thermoelectric materials by controlling not just their composition, but the relationships between the component materials.