Collaborative Research: Exploring thermionic multiple barrier heterostructures and thermoelectric energy conversion using 2D layered heterostructures

合作研究：利用二维层状异质结构探索热离子多重势垒异质结构和热电能量转换

• 批准号: 2323031
• 负责人: Stephen Cronin
• 金额: $ 23万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2323031&HistoricalAwards=false
• 关键词: Collaborative; Research; Exploring; thermionic; multiple

Solid-state thermionic energy conversion has been predicted to be more efficient than conventional thermoelectric energy conversion based on bulk Peltier and Seebeck effects, if the thermionic barriers can be properly engineered. However, there have been relatively few experimental studies on solid-state thermionic energy conversion, mainly because of the difficulty of fabricating interfaces with the appropriate energy barriers, characterizing thermal transport across these interfaces, and separating the bulk thermoelectric properties from the interfacial properties. The proposed 2D Layered heterostructures enable these difficulties to be overcome and can potentially create a paradigm shift in the design of thermoelectric power generators and coolers with high efficiency. The project will also encompass significant educational activities, including an undergraduate research program and an outreach workshop for high school science teachers.The goal of the study is to develop a fundamental understanding of thermionic transport and energy conversion in multiple-barrier heterostructures using 2D-layered materials. Since the thermionic barriers must be thin, each barrier can have only a small temperature difference across it. Hence, macroscopic cooling and power generation needs to be obtained using multistage devices. In the proposed work, heterostructures are synthesized by physical vapor deposition (PVD), which can be used to produce heterostructures with hundreds of periods quite easily. These structures would be nearly impossible to fabricate by mechanical exfoliation. Unlike molecular beam epitaxy (MBE), the material synthesis approach proposed here is liftoff-compatible, enabling reliable measurements of cross-plane transport phenomena (electrical, thermal, and thermoelectric) using a new approach developed in the PIs’ labs. This new cross-plane measurement approach together with the configurable nanoarchitecture (i.e., layer thicknesses and total thickness) will enable the bulk and interfacial (i.e., thermionic emission) contributions to the thermovoltage to be separated. A phenomenological model of the electron and phonon transport across these novel devices will be developed using a thermionic emission transport approach. The proposed heterostructure geometries open up new degrees of freedom in the cross-plane transport with independent control of electrons and phonons, which is essential for achieving efficient energy conversion devices.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.

如果可以正确地设计热屏障，则固态热能转化率比基于散装层和Seebeck效应的常规热电能量转换更有效。然而，关于固态热能转化的实验研究相对较少，这主要是因为难以与适当的能屏障制造界面，表征跨这些界面的热传输，并将散装热电特性与界面特性分开。提出的2D层次异质结构使这些困难能够克服，并有可能在高效效率的热电发电机和冷却器的设计中产生范式转移。该项目还将涵盖重要的教育活动，包括一项本科研究计划和高中科学教师的外展研讨会。该研究的目的是使用2D层的材料对多级式异质结构中的热运输和能量转换进行基本了解。由于热屏障必须很薄，因此每个屏障在其上只能有较小的温度差。因此，需要使用多阶段设备获得宏观冷却和发电。在拟议的工作中，异质结构是由物理蒸气沉积（PVD）合成的，可用于生产具有数百个周期的异质结构。这些结构几乎不可能通过机械去角质来制造。与分子束外延（MBE）不同，此处提出的材料合成方法是升降兼容的，可以使用PIS实验室中开发的新方法对跨平面转运现象（电气，热电和热电）的可靠测量。这种新的跨平面测量方法以及可配置的纳米结构（即，层厚度和总厚度）将使对热电压的散装和界面（即热发射）贡献。将使用热发射传输方法开发电子和声子传输的现象学模型。拟议的异质结构几何形状通过独立控制电子和声子为跨平面传输开放了新的自由度，这对于实现有效的能量转换设备至关重要。该奖项反映了NSF的法定任务，并被认为是通过使用基金会的智力和更广泛的影响来通过评估来获得支持的珍贵的，这是珍贵的。