EAGER: In-situ spectral phonon recycling in LED for improved thermal, power and performance efficiency

根据美国能源信息署的数据，照明消耗相当于美国总用电量的5%。发光二极管（LED）的使用提高了照明效率，但仍有超过50%的电能以热量（发射声子）的形式耗散。提高能量转换和展示及时和显着的影响声子工程使用氮化镓GaN LED是这个建议的EAGER的目标。这将通过向LED结构添加异质势垒（HB）层来实现，用于声子发射的净吸收和再循环，这将提供改进的功率效率。目标是从理论上预测改进，制造和测试最佳设计，旨在证明概念验证并使其可用于技术实施。通过与GaN LED和显示器专家的合作，可以在商业层面实施拟议的改进验证，从而显著节省国家能源并增强设备热管理。对声子-电子-光子相互作用的基本理解和深刻利用推进了传热物理和工程。 这项研究将是首次尝试在LED中使用渐变HB进行原位光谱声子回收。该研究结合了声子传输和回收行为的模拟，以理解和推进声子回收的新想法，并包括对新概念的实验验证。因此，为期一年的EAGER努力的重点是展示LED声子回收的新概念，如果成功的话，可以在节能方面提供显着的回报。所提出的研究推进了这样的前提，即通过HB的声子再循环的益处是通过三种不同的途径实现的：（a）减少热负荷，导致LED的温度降低（B）增加功率效率，其中LED中的电流收获声子能量，产生净电势增益，以及（c）由于HB层中的净电势增益而增强光子发射光谱。拟议研究中的预测使用中尺度（玻尔兹曼输运）相互作用，其中涉及声子，电子和空穴以及光子。最佳HB GaN LED的制造和测试/表征将提供有史以来第一次通过使用HB改善LED性能和节能的实验演示。拟议的研究符合能源部固态照明研发目标的2035年，这将使国家能源节约相当于美国能源消耗的3%，在2022年。这一奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

Lighting consumes equivalent to 5% of total US electricity use according to US Energy Information Administration. The use of light emitting diodes (LEDs) has improved the lighting efficiency, but still more than 50% of the electrical energy is dissipated as heat (emitted phonons). Improving energy conversion and demonstrating timely and significant impact of phonon engineering using gallium-nitride GaN LED is the goal of this proposed EAGER. This will be done by adding a heterobarrier (HB) layer to the LED structure for a net absorption and recycling of phonon emissions that will provide improved power efficiency. The objectives are to theoretically predict the improvements and to fabricate and test the optimal design, aiming to demonstrate the proof-of-concept and make it available for technological implementations. Through collaboration with an GaN LED and display expert, the proposed improvement verifications can be implemented at commercial level resulting in significant national energy savings and enhanced device thermal management. Fundamental understanding and insightful use of the phonon-electron-photon interactions advance the heat transfer physics and engineering. The proposed research would be the first attempt at in-situ spectral-phonon recycling in LED using a graded HB. The research combines simulations of the phonon transport and recycling behavior to understand and advance the novel idea of phonon recycling, and also includes an experimental verification of the new concept. The one-year EAGER effort is therefore focused on demonstrating the new concept of phonon-recycling for LEDs, and if successful can provide significant paybacks in terms of energy savings. The proposed research advances the premise that the benefits of phonon-recycling via the HB is achieved through three distinct pathways: (a) reduced heat load resulting in a temperature decrease for LEDs (b) increased power efficiency, where the electric current in the LED harvests phonon energy, creating a net potential gain, and (c) enhanced photon emission spectra due to the net potential gain in the HB layer. The predictions in the proposed research use mesoscale (Boltzmann transport) interactions, which involves phonons, electrons and holes, and photons. The fabrication and testing/characterization of the optimal HB GaN LED will provide the first ever experimental demonstration of improvements in LED performance and energy savings via the use of a HB. The proposed research aligns with the Department of Energy solid-state lighting R&D goals for 2035 which would enable national energy savings equivalent to 3% of US energy consumption in 2022.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.