IDR: Molecular engineering of thermal interfaces

IDR：热界面的分子工程1134311 Avik Ghosh，Patrick E.Hopkins&Amp；Lloyd R.Harriott Engineering固体材料中的热传导对于广泛的应用是必不可少的，从电子产品的热管理到发电，再到信息技术。许多这样的现代系统包括具有数十到数百纳米量级的特征长度尺度的材料和结构。在这些长度尺度上，主要热阻出现在两种材料之间的界面上，导致纳米系统的热特性强烈地由这些固体界面决定。因此，开发控制和调节界面上的热传输的机制以能够准确地管理纳米系统的热性质是至关重要的。为了实现这一点，该项目将探索两个固体层之间的热传输，这是由界面上生长的有机分子的性质控制的。通过宽带、空间局域分子振子和窄带、空间离域衬底声子之间的相互作用，该项目将致力于在分子尺度上对材料界面的组成、形态和声子能带结构进行系统和有针对性的工程，以实现界面热导的高度可调谐。将启动一项结合和紧密耦合的理论和实验研究，探索各种类型的有机分子自组装单分子膜(SAM)作为热界面材料，作为SAM和衬底质量和材料等变量的函数，利用自组装，最重要的是丰富的各种功能化学。通过大量基于SAM的接口的热传输将用时间域热反射系数来测量。实验结果将与使用非平衡格林函数形式的从头计算建模工作强烈耦合。该项目所发现的科学也将广泛应用于一般金属和半导体界面系统的热工程。这项拟议工作的智力价值在于发展了对纳米尺度界面热性质的新理解。这将被证明对热流的原子化控制至关重要。通过理论和实验之间的密切协作，这项研究将把分子热流背后的原子论概念与整体热流的固态概念结合起来，加强对最基本、微观极限上的热流和耗散的理解。它将在学科、材料以及最终在基础科学和技术应用之间架起一座桥梁。准确的、有良好基准的模拟将解决带对齐和化学在固体分子界面上的关键作用。实验将集中于制造定义良好的基于SAM的界面结构，通过分子化学、表征和测量热界面阻来对其进行修改，以创建高质量的可调热界。该项目的更广泛影响包括工程相关性和教育/外联部分。所获得的知识将在纳米科学中引入一个新的概念：通过分子化学进行热界面控制和工程。纳米级的热管理和控制将给科学、技术和经济带来颠覆性变化，从卓越的质量和量身定做的热涂层和热电冰箱，到价值数十亿美元的半导体行业更好的热管理。教育和外展活动将包括在弗吉尼亚大学创建纳米课程，编写关于热传导的教程，通过热传输实验室在PIS教授的课程中整合研究和教育，在本科生参与的情况下组织关于分子热传递的会议，通过REU计划吸引少数族裔本科生参与暑期项目，以及利用UVA的工程多样性中心为课程开发培训中学教师。

IDR: Molecular Engineering of Thermal Interfaces 1134311Avik Ghosh, Patrick E. Hopkins & Lloyd R. Harriott Engineering the conduction of heat in solid materials is essential for a wide array of applications, ranging from thermal management of electronics, to power generation, to information technology. Many of these modern systems include materials and structures with characteristic length scales on the order of tens to hundreds of nanometers. At these length scales, the major thermal resistances arise at the interfaces between two materials, leading to thermal properties of nanosystems that are strongly dictated by these solid interfaces. Therefore, it is of utmost importance to develop mechanisms of controlling and tuning the thermal transport across interfaces to be able to accurately manage the thermal properties of nanosystems. To achieve this, this project will explore thermal transport between two solid layers, controlled by properties of organic molecules grown at their interface. Through the interplay between the wide-band, spatially localized molecular vibrons and the narrow-band, spatially delocalized substrate phonons, the project will aim for the systematic and targeted engineering of the composition, morphology and phonon bandstructures of material interfaces at the molecular scale in order to achieve a high degree of tunability of the interfacial thermal conductance. A combined and closely coupled theoretical and experimental study will be launched exploring various classes of self-assembled monolayers (SAMs) of organic molecules as thermal interfacial materials, as a function of variables such as the SAM and substrate quality and material, utilizing self-assembly and most importantly a rich variety of functional chemistry. The thermal transport across the wide array of SAM-based interfaces will be measured with time domain thermoreflectance. The experimental results will be strongly coupled with ab initio modeling efforts utilizing Nonequilibrium Green's Functions formalisms. The science discovered in this project will also be widely applicable to thermal engineering of generic metal and semiconductor interfacial systems.The intellectual merit of this proposed work is in the development of a new understanding of nanoscale interfacial thermal properties. This will prove critical for the atomistic control of heat flow. Through the close synergy between theory and experiment, the study will enhance the understanding of heat flow and dissipation at their most fundamental, microscopic limits, combining atomistic concepts behind molecular heat flow with solid state concepts of bulk heat flow. It will bridge disciplines, materials, and ultimately the boundary between fundamental science and technological applications. Accurate, well benchmarked simulations will address the critical role of band-alignment and chemistry at the solid-molecular interface. Experiments will focus on fabrication of well-defined SAM-based interfacial structures, modifying them through molecular chemistry, characterization and measurement of thermal boundary resistances with a goal towards creating high quality tunable thermal boundaries. The broader impacts of this project include both engineering relevance and education/outreach components. The knowledge gained will introduce a new concept in nanoscale science: thermal interface control and engineering via molecular chemistry. Nanoscale thermal management and control will bring about disruptive changes to science, technology and economics, ranging from superior quality and tailor-made thermal coatings and thermoelectric refrigerators, to better heat management in the multi-billion dollar semiconductor industry. Educational and outreach activities will involve creation of a nano-curriculum at UVa, tutorial creation on the thermalHUB, integration of research and education through thermal transport labs in courses taught by the PIs, conference organization of session on molecular heat transfer with undergraduate involvement, engaging minority undergraduate students for summer projects through the REU program and training middle school teachers for curriculum development utilizing UVA's Center for Diversity in Engineering.