Collaborative Research: Electric Field- and Light-Modulated Thermal Transport in Superatomic Crystals

材料的传热能力取决于其导热性。高导热性材料是热导体，而低导热性材料是热绝缘体。该项目的目标是发现导热系数可以快速改变的材料。这种热传导开关将有助于降低间歇性过热的电子设备的温度，并将热量转化为电能。所提出的方法是基于控制分子在一类称为超原子晶体的新材料中的旋转。当分子旋转时，热导率低。电场或光的应用将导致分子停止旋转并增加热导率。支持的研究生将从不同的人才库中招募，并将获得化学，热传输和材料科学方面的跨领域实验和建模经验。该团队将开发教育模块，让初中、高中和大学生了解材料的原子结构和性质之间的联系。超原子晶体是由称为超原子的精确分子构建块组装而成的。它们的可扩展合成和多功能特性使它们对能量转换应用具有吸引力。定向障碍（即，旋转）降低了它们的热导率。该项目的首要假设是，C60取向障碍可以使用电场和光主动操纵。通过哥伦比亚的合成和晶体学以及卡内基梅隆大学的热传输测量和原子模型，这一假设将在新型超原子晶体[Co6Te 8][C60]3上得到验证。由电场和光引发的极性嵌入物和光敏配体将成为锁定超原子晶体的C60齿轮的猴子扳手，以根据需要切换热导率。这种热开关可用于从稳态源产生瞬态热通量，以提高热电和热电器件的性能。热开关还将实现对热路径的主动控制，以及管理电子设备中热量的新方法。三个跨学科的教程将介绍化学专业的学生热传输和工程专业的学生化学键和上层建筑。在匹兹堡和纽约服务不足的社区开展的外联活动将使中学生接触到化学和工程的交叉点。该项目支持的研究生将从不同的人才库中招募，并将获得化学，X射线晶体学，光学和计算材料科学的跨学科经验。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

The ability for a material to transport heat is governed by its thermal conductivity. High thermal conductivity materials are thermal conductors, while low thermal conductivity materials are thermal insulators. The objective of this project is to discover materials whose thermal conductivity can be quickly changed. Such thermal conductivity switches will be useful in reducing the temperature of electronic devices that intermittently overheat and in converting heat into electricity. The proposed approach is based on controlling the rotations of molecules inside a new class of material called superatomic crystals. When the molecules rotate, the thermal conductivity is low. The application of an electric field or light will cause the molecules to stop rotating and increase thermal conductivity. The supported graduate students will be recruited from diverse pools and will gain cross-cutting experimental and modeling experience in chemistry, thermal transport, and materials science. The team will develop educational modules to expose middle school, high school, and undergraduate students to the links between a material’s atomic structure and its properties.Superatomic crystals are assembled from precise molecular building blocks called superatoms. Their scalable synthesis and multi-functional properties make them attractive for energy conversion applications. Orientational disorder (i.e., rotation) of C60 superatoms in some superatomic crystals at elevated temperatures decreases their thermal conductivity. The overarching hypothesis of this project is that C60 orientational disorder can be actively manipulated using electric fields and light. Through synthesis and crystallography at Columbia and thermal transport measurements and atomistic modeling at Carnegie Mellon, this hypothesis will be tested on the novel superatomic crystal [Co6Te8][C60]3. Polar intercalants and photoactive ligands, triggered by electric fields and light, will become monkey wrenches that lock the C60 gears of the superatomic crystals to switch thermal conductivity on demand. Such thermal switches can be used to create transient heat fluxes from steady-state sources to improve the performance of pyroelectric and thermoelectric devices. Thermal switches will also enable active control of heat pathways and new approaches for managing heat in electronics. Three interdisciplinary tutorials will introduce chemistry students to thermal transport and engineering students to chemical bonding and superstructures. Outreach activities in underserved communities in Pittsburgh and New York will expose middle and high school students to the intersection of chemistry and engineering. The graduate students supported by the project will be recruited from diverse pools and will gain interdisciplinary experience in chemistry, X-ray crystallography, optics, and computational materials science.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.