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Non-Hermitian nanophotonics for efficient thermophotovoltaic energy conversion

用于高效热光伏能量转换的非厄米纳米光子学

基本信息

批准号：
1935446
负责人：
Gururaj Naik
金额：
$ 30万
依托单位：
William Marsh Rice University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-09-15 至 2023-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1935446&HistoricalAwards=false
关键词：
Non Hermitian nanophotonics efficient thermophotovoltaic

项目摘要

Meeting the rising global energy need with clean and efficient energy systems is one of the greatest technological challenges of our time. Efficient conversion of heat and light to electricity is crucial in overcoming this challenge. Thermophotovoltaics is a promising technique for efficiently converting heat to electricity via light without any moving parts. The heat generated from industrial processes, nuclear fission reaction, automobile exhaust or absorption of sunlight results in thermal light radiating from hot surfaces. Photovoltaic conversion of this thermal light to electricity as in solar cells is called thermophotovoltaic conversion. The theoretical efficiency limit of thermophotovoltaic systems can be as high as 80%, though experimental demonstrations lie far below this number. The primary reason for low efficiency is the broadband nature of thermal light radiating from hot surfaces. Squeezing thermal light into a narrow band of frequencies is a challenging task especially when operating at high temperatures. This project aims to develop novel strategies to confine thermal light to a narrow band of frequencies and demonstrate efficient conversion of heat to light. Successful implementation of the project will result in discovering new tools to achieve extreme control on the flow of light and heat, educate and train next-generation scientists, and develop an efficient heat-to-electricity conversion technology for energy generation and storage applications. Given that the on-grid industrial waste heat alone is nearly 20% of the total industrial energy consumption, efficient thermophotovoltaic systems can make a huge impact in meeting the clean energy needs of the planet.Technical description: Thermal radiation from hot surfaces is typically broadband in nature and limit the overall efficiency of thermophotovoltaic conversion. Confining thermal radiation to a narrow spectral band is the key to this problem. Previous attempts have investigated various nanophotonic principles to design narrowband thermal emitters or selective emitters, though their performance is still inadequate. All nanostructured optical materials degrade at high temperatures. Their optical losses significantly increase with temperature and limit the maximum possible spectral selectivity. Calculations show that a spectral contrast of at least 20 dB is required for efficient thermophotovoltaic conversion. Such high contrast over broad infrared wavelengths is not possible by conventional approach due to high optical losses in the constituent materials. Here in this project, an unorthodox approach using non-Hermitian physics or quantum optical description of resonant emitters is adopted to design thermal emitters. Unlike the conventional approach, non-Hermitian design exploits high optical losses in materials to simultaneously achieve high contrast and high emissivity. Further, a quantum optical description of the selective emitter allows its design as a system of coupled multiple nanoscale resonators. Such an approach is a paradigm shift in the design of selective emitters allowing novel many-body physical phenomena to be observed in thermal emission. As a result, new design tools such as symmetry, topology and internal phase of resonators present an unprecedented opportunity to extreme-engineer thermal emitters. This project aims to investigate the effect of these new design tools on the spatial and spectral properties of thermal radiation, build selective emitters with high contrast, directionality, and brightness, and demonstrate high-efficiency thermophotovoltaic conversion.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.

用清洁高效的能源系统满足全球日益增长的能源需求是我们这个时代最大的技术挑战之一。将热和光有效地转化为电能对于克服这一挑战至关重要。热光电转换技术是一种很有前途的技术，可以在没有任何运动部件的情况下通过光有效地将热量转换为电能。工业过程、核裂变反应、汽车尾气或太阳光吸收产生的热量导致热光从热表面辐射。太阳能电池中这种热光到电的光伏转换称为热光伏转换。热光伏系统的理论效率极限可以高达80%，尽管实验证明远低于这个数字。低效率的主要原因是从热表面辐射的热光的宽带性质。将热光压缩成窄频带是一项具有挑战性的任务，特别是在高温下工作时。该项目旨在开发新的策略，将热光限制在狭窄的频率范围内，并展示热到光的有效转换。该项目的成功实施将导致发现新的工具，以实现对光和热的流动的极端控制，教育和培训下一代科学家，并开发用于能源生产和存储应用的高效热电转换技术。鉴于仅并网工业废热就占工业总能耗的近20%，高效的热光伏系统可以在满足地球清洁能源需求方面发挥巨大作用。技术描述：热表面的热辐射通常具有宽带特性，限制了热光伏转换的整体效率。将热辐射限制在一个狭窄的光谱带是解决这个问题的关键。之前的尝试已经研究了各种纳米光子原理来设计窄带热发射器或选择性发射器，但它们的性能仍然不够。所有的纳米结构光学材料在高温下都会降解。它们的光学损耗随温度显著增加，并限制了最大可能的光谱选择性。计算表明，有效的热光伏转换需要至少20 dB的光谱对比度。由于组成材料中的高光学损耗，通过常规方法在宽红外波长上的这种高对比度是不可能的。在本计画中，我们采用非正统的方法，使用非厄米物理或量子光学的共振辐射体描述来设计热辐射体。与传统方法不同，非厄米设计利用材料中的高光学损耗来同时实现高对比度和高发射率。此外，选择性发射器的量子光学描述允许其设计为耦合的多个纳米级谐振器的系统。这种方法是一种范式转变，在设计的选择性发射器，允许新的多体物理现象被观察到的热发射。因此，新的设计工具，如对称性，拓扑结构和谐振器的内部相位提出了一个前所未有的机会，极端工程热发射器。该项目旨在研究这些新的设计工具对热辐射的空间和光谱特性的影响，构建具有高对比度、方向性和亮度的选择性发射器，并展示高效的热光伏转换。该奖项反映了NSF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。