CAREER: Quantum Size Effects on Thermal Radiation

量子尺度(即纳米和亚纳米尺度)材料表现出与普通块体材料显著不同的热辐射特性。这一现象是由材料在量子尺度上的电子能带结构的变化引起的。量子材料的热辐射可以利用纳米间隙热光电技术进行高效的余热回收，也可以用于辐射冷却和智能窗户。此外，量子尺度的热辐射对晶体管和超紧凑型电子产品的热管理有重大影响。尽管有这一重要意义，但热辐射是如何在量子水平上发射和交换的还没有被很好地理解。这个项目将阐明量子体制下热辐射的基本机制。这项研究可以导致能源收集和节约方面的技术突破。这将通过节约有限的能源和保护环境来影响社会。残疾学生、缅因州农村地区的女学生和高中教师将直接参与这项研究。首席研究员系将开设一门关于辐射热传递的新课程和三个实验课程。量子尺寸效应对热辐射有重要影响，主要原因有两个。首先，量子材料(即在原子长度尺度上设计的材料)的光学和电学(因此也就是热辐射)性质可能与块状材料有很大不同。这为设计具有超越涨落电动力学机制的热辐射特性的材料提供了极好的机会。其次，原子长度尺度的辐射热传递可以在晶体管、超紧凑型电路、量子计算机、太阳能电池和医学成像仪等设备的热管理中发挥重要作用。在原子尺度的间隔能隙中，产生了声子和电子隧穿等量子尺寸效应。与波动电动力学预测相比，这些效应可以修正辐射换热。虽然人们已经研究了声子隧穿对两种介质之间辐射换热的影响，但对存在电子隧穿的金属介质之间的辐射换热还没有完全了解。本研究项目将通过(1)建立模拟量子材料热辐射的理论框架，(2)不同维度的量子材料的热辐射的理论研究，(3)量子尺寸效应对热辐射的大小和光谱的实验演示，来阐明量子尺寸对热辐射的影响。以及(4)研究电子隧穿对量子尺度分离缝隙辐射热传输的影响。该项目由热传输过程计划和既定的激励竞争研究计划(EPSCoR)联合资助。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。

Quantum-scale (i.e., nanometer and sub-nanometer scale) materials exhibit thermal radiation properties that are significantly different from ordinary bulk materials. This phenomenon is caused by the change in the electronic band structure of the materials at the quantum scale. Thermal radiation of quantum materials can be engineered for highly efficient waste heat recovery using nano-gap thermophotovoltaics as well as for radiative cooling and smart windows. Additionally, thermal radiation at the quantum scale has significant impact on thermal management of transistors and ultra-compact electronics. Despite this significance, how thermal radiation is emitted and exchanged at the quantum level is not well understood. This project will elucidate the fundamental mechanisms underlying thermal radiation in the quantum regime. This research can lead to technological breakthroughs in energy harvesting and conservation. This will impact society by conserving limited energy resources and protecting the environment. Students with disabilities, female students from rural areas of Maine, and high school teachers will be directly involved in this research. A new course and three lab sessions on radiative heat transfer will be developed at the principal investigator’s department.Quantum size effects on thermal radiation are significant for two chief reasons. First, optical and electronic (and thus thermal radiative) properties of quantum materials (i.e., materials that are engineered at the atomic length scale) can differ drastically from bulk materials. This opens up a great opportunity for designing materials with tailored thermal radiative properties beyond the fluctuational-electrodynamics regime. Second, radiative heat transfer at the atomic length scale can play a significant role in thermal management of devices such as transistors, ultra-compact circuits, quantum computers, solar cells, and medical imagers. At atomic scale separation gaps, quantum size effects such as phonon and electron tunneling arise. These effects can modify radiative heat transfer compared to the fluctuational electrodynamics predictions. Although the effect of phonon tunneling on radiative heat transfer between two dielectric media has been studied, radiative heat transfer between metallic media in the presence of electron tunneling is not fully understood. This research project will elucidate quantum size effects on thermal radiation by (1) establishing a theoretical framework for modeling thermal radiation of quantum materials, (2) a theoretical study of thermal radiation by quantum materials of different dimensions, (3) experimental demonstration of quantum size effects on the magnitude and the spectrum of thermal emission, and (4) studying the effect of electron tunneling on radiative heat transfer at quantum-scale separation gaps.This project is jointly funded by the Thermal Transport Processes Program and the Established Program to Stimulate Competitive Research (EPSCoR).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.