CAREER: Investigation of Thermal Transport in Moiré Pattern Structured Materials to Push the Extremes of Thermal Modulation

该奖项的全部或部分资金来自《2021年美国救援计划法案》(公共法律117-2)。基于石墨烯等原子薄晶体的二维(2D)材料制成的可穿戴设备有望通过实现高灵活性、固有的薄性和前所未有的设备性能来彻底改变现代微电子。然而，推进多样化和变革性应用的一个重大挑战是获得对热运输的控制。例如，需要增加热传输，以补偿在高应力水平下由于导热系数降低而引起的发热问题，并需要减少热传输，以实现有效的热电能量转换和隔热设备。本研究的首要目标是通过控制二维材料的云纹来实现高效、原位和可逆的热控制，云纹是通过调整两种二维材料之间不匹配的晶格的相对扭角而产生的。所学到的知识可能会推动由原子薄2D材料制成的皮肤状可穿戴设备的热调制极限，并使从Beyond-Si电子设备和传感器到超导热开关的现代设备成为可能。该项目将研究、教育和推广紧密结合在一起，通过互动游戏、工作坊、新课程、动手研究指导和研究工具共享，让学生参与到热技术中来。拟议的研究旨在创造关于晶格有序使热输运的新知识，并将扭曲角度调节作为一种强大的热调制策略。应用于2D云纹结构材料的扭转角度调谐方法提供了一种原位、连续和可逆的调谐策略，无需改变材料的化学成分，从而绕过了与传统可穿戴设备相关的挑战。重点介绍了材料合成、器件纳米制造和热表征的实验方法，并通过解析模型加以加强。通过系统地改变扭曲角度以及二维莫尔图案的机械变形和整体几何形状，将揭示对晶格有序、晶格常数、几何形状和热导率的深入了解。这些知识将是对热物理基本理解的重大飞跃，建立热调制原理以实现预期的热传输结果，并彻底改变未来的可穿戴设备平台。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Wearable devices made of two-dimensional (2D) materials based on atomically thin crystals such as graphene promise to revolutionize modern microelectronics by enabling high flexibility, intrinsic thinness, and unprecedented device performance. However, one significant challenge to the advancement of diverse and transformative applications is gaining control over thermal transport. For example, thermal transport needs to be increased to compensate for the heating issue caused by the reduced thermal conductivity at high levels of stress and decreased for efficient thermoelectric energy conversion and thermal insulation devices. The overarching goal of this research is to achieve efficient, in-situ, and reversible thermal control via manipulating 2D materials’ Moiré patterns, which are created by adjusting the relative twist angle of mismatching crystal lattice between the two 2D materials. The knowledge learned will potentially push the thermal modulation limits in skin-like wearable devices made of atomically thin 2D materials, and enable modern devices from beyond-Si electronics and sensors to superconducting thermal switches. This project will tightly integrate research, education and outreach, with interactive games, workshops, novel curriculum, hands-on research mentoring, and research tool sharing to engage students in thermal technology.The proposed research aims to create new knowledge about crystal lattice order enabled thermal transport and develop twist angle tuning as a powerful strategy for thermal modulation. The twist angle tuning method applied to 2D Moiré pattern structured materials provides an in-situ, continuous and reversible tuning strategy without the need for changing the materials’ chemical composition, thereby bypassing the challenges associated with traditional wearable devices. Experimental approaches of materials synthesis, device nanofabrication and thermal characterization are emphasized and reinforced by analytical modeling. By systematically varying twist angle as well as the 2D Moiré patterns’ mechanical deformation and global geometry, in-depth understanding of lattice orders, lattice constants, geometry and thermal conductivity will be uncovered. Such knowledge will be a major leap in fundamental understanding of thermal physics, establish thermal modulation principles to achieve desired thermal transport outcomes, and revolutionize future wearable device platforms.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.