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

材料传递热量的能力是由它的导热性决定的。高导热系数的材料是导热体，低导热系数的材料是绝缘体。这个项目的目标是发现导热性可以快速改变的材料。这种导热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。提出的方法是基于控制一种被称为超原子晶体的新材料内分子的旋转。当分子旋转时，热导率低。施加电场或光会使分子停止旋转，增加导热性。支持的研究生将从不同的池中招募，并将获得化学，热输运和材料科学的交叉实验和建模经验。该团队将开发教育模块，让初中生、高中生和大学生了解材料的原子结构和性质之间的联系。超原子晶体是由被称为超原子的精确分子组成的。它们的可扩展合成和多功能特性使它们在能量转换应用中具有吸引力。某些超原子晶体中C60超原子在高温下的取向紊乱（即旋转）降低了它们的导热性。这个项目的首要假设是C60取向紊乱可以通过电场和光来主动控制。通过哥伦比亚大学的合成和晶体学以及卡耐基梅隆大学的热输运测量和原子模型，这一假设将在新型超原子晶体[Co6Te8][C60]3上得到验证。极性插入剂和光活性配体在电场和光的作用下，将成为锁住超原子晶体C60齿轮的扳手，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流，以改善热释电和热电器件的性能。热开关也将使热途径的主动控制和管理电子热的新方法成为可能。三个跨学科的教程将向化学专业的学生介绍热输运，向工程专业的学生介绍化学键和上层结构。在匹兹堡和纽约服务不足的社区开展的拓展活动将使初高中学生接触到化学和工程的交叉。该项目支持的研究生将从不同的领域招募，并将在化学、x射线晶体学、光学和计算材料科学方面获得跨学科的经验。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识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.