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

自下而上控制混合二维材料中的热传输开发能够将废热直接转化为电能的高效热电材料已成为纳米科学和技术的最终目标之一。利用纳米结构材料的独特性能，在热电材料的发展方面取得了令人难以置信的进展。然而，尽管取得了这些进展，但仍然很难准确预测这些复杂系统的性质将如何随着尺寸尺度的变化而演变，或者修改组件材料将如何影响最终的系统性质。这种困难的主要原因之一是，改善系统的热电性能需要同时控制三种性能：电导率，热功率（塞贝克系数）和热导率。该项目将使用混合，2维（2D），分子-纳米颗粒材料作为探索纳米结构热电材料的热传输特性的模型系统。这是一个独特的材料系统，其中单个组件的特性可以被测量，控制和表征，然后嵌入到混合材料中，以便随着系统的扩大或组件的修改，可以确定组件之间的复杂相互作用。通过研究分子组分的热和机械性质，以及这些性质对杂化材料热输运的影响，本项目旨在开发一套用于控制杂化分子-纳米颗粒热电器件热输运性质的设计规则。然后，可以利用这些知识来更全面地了解纳米结构材料中控制热传输的特性，以便从原子级开始设计这些系统的热传输特性的控制。该项目将通过以下方法来理解和控制杂化材料的热输运性质：i）检查分子取代基的振动态密度对热输运性质的作用; ii）研究分子刚性和纳米颗粒质量和组成如何影响热输运; iii）研究阵列的热输运性质随系统尺寸尺度的演变;和iv）检查这些性质之间的相互作用，以能够设计具有所需性质的纳米结构体系。这项调查将提供前所未有的信息之间的相互作用的原子尺度的热性能的组件材料和集成，混合材料的性能在一系列的尺寸尺度。使用单分子光谱技术（非弹性电子调谐光谱，机电？阿尔法光谱学）、纳米颗粒尺寸和组成的修改以及特征尺寸的光刻控制将揭示分子和纳米颗粒性质如何决定2D混合分子-纳米颗粒阵列的热传输性质。这些研究将提供有关这些属性中哪些主导纳米结构材料中的热传输，它们之间的关系以及这种相互作用如何随着设备尺寸的缩放而演变的关键信息。这一系列系统的实验将使人们对纳米结构材料中的热传输原理有一个新的理解，并使热传输的被动控制设计成热电材料，不仅控制它们的成分，而且控制组成材料之间的关系。

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.