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.

据预测，如果能适当地设计热离子势垒，固态热离子能量转换将比基于体Peltier和Seebeck效应的传统热电能量转换更有效。然而，关于固态热电子能量转换的实验研究相对较少，主要是因为难以制造具有适当能量势垒的界面，表征这些界面上的热输运，以及将体热电性质与界面性质分开。所提出的二维层状异质结构能够克服这些困难，并可能在高效率热电发电机和冷却器的设计中创造范式转变。该项目还将包括重要的教育活动，包括一个本科研究项目和一个面向高中科学教师的拓展讲习班。该研究的目标是对使用二维层状材料的多势垒异质结构中的热离子传输和能量转换有一个基本的了解。由于热离子势垒必须很薄，每个势垒之间只能有很小的温差。因此，需要使用多级装置来获得宏观冷却和发电。本研究采用物理气相沉积（PVD）方法合成异质结构，制备具有数百个周期的异质结构非常容易。这些结构几乎不可能通过机械剥离来制造。与分子束外延（MBE）不同，这里提出的材料合成方法是起飞兼容的，可以使用pi实验室开发的新方法可靠地测量跨平面传输现象（电、热、热电）。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）将使体和界面（即热离子发射）对热电压的贡献得以分离。电子和声子在这些新型器件上传输的现象学模型将使用热离子发射传输方法进行开发。所提出的异质结构几何形状在电子和声子独立控制的跨平面传输中开辟了新的自由度，这对于实现高效的能量转换装置至关重要。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。