CAREER: Phonon Scattering By Electrons: From Fundamental Understanding To Thermal Transport Control

在我们的能源系统中，对热传输过程的基本理解和控制对于提高能源效率和社会的可持续性至关重要，因为目前每年有超过60%的总能源消耗以废热的形式被拒绝。有效控制热传递仍然是一项技术挑战，因为固体材料中的主要热载体通常对外部影响不太敏感。这个CAREER项目研究了一种控制固体热传输的新方法的理论基础和实际可行性：使用外部电磁场来显著改变传热过程。这个项目不仅提高了我们对最先进材料和设备的能源传输的基本理解，而且通过提供新的实用策略来设计更高效和可持续的能源系统，使社会受益。这个CAREER项目还侧重于通过让K-12和本科生接触可再生能源收集项目，提高下一代可再生能源技术的劳动力准备程度，并通过为来自代表性不足的少数民族社区的本科生研究人员提供研究机会，促进可再生能源领域的多样性。该项目的首要目标是了解声子和电子之间的相互作用如何改变固态材料的热输运特性。这个项目的动机是我们最近发现声子-电子散射可以成为室温下高电子浓度半导体中主要的声子散射机制。理论上，最先进的第一性原理声子-电子散射计算与耦合玻尔兹曼输运方程将被用来理解声子-电子散射的衰减和放大，揭示决定声子-电子散射强度的关键因素，并识别具有强声子-电子散射的材料用于潜在的热交换应用。实验方面，将发展并应用超快光学和电子能谱方法来表征不同频率、动量和极化声子模式的声子-电子散射强度，并通过外部光激发和静电门控来改变声子-电子散射，证明固态热开关。这个CAREER项目不仅为高电子浓度设备的能量传递过程提供了新的见解，而且为开发基于微观能量载体相互作用的新型功能能源材料和设备提供了变革性的机会。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。

Fundamental understanding and control of heat transport processes in our energy systems is crucial to improve the energy efficiency and sustainability of our society, as currently over 60% of our total energy consumption is rejected in the form of waste heat each year. Effective control of the heat transport remains a technological challenge because major heat carriers in solid materials are typically less sensitive to external influence. This CAREER project examines the theoretical basis and practical feasibility of a novel means to control heat transport in solids: using external electromagnetic fields to significantly alter the heat transfer processes. This project not only advances our fundamental understanding of energy transport in state-of-the-art materials and devices, but also benefits the society by providing new practical strategies to design more efficient and sustainable energy systems. This CAREER project also focuses on raising the workforce readiness for next-generation renewable energy technologies by exposing K-12 and undergraduate students to hands-on renewable energy harvesting projects, and promoting the diversity of the renewable energy field by providing research opportunities to undergraduate researchers from underrepresented minority communities.The overarching goal of this project is to understand how the interaction between phonons and electrons can modify the thermal transport properties of solid-state materials. This project is motivated by our recent finding that phonon-electron scattering can become the dominant phonon scattering mechanism in semiconductors with high electron concentrations at room temperature. Theoretically, state-of-the-art first-principles phonon-electron scattering calculation with coupled Boltzmann transport equations will be employed to understand phonon damping and amplification by phonon-electron scattering, reveal key factors that determine the strength of phonon-electron scattering and identify materials with strong phonon-electron scattering for potential thermal switching applications. Experimentally, ultrafast optical and electron spectroscopic methods will be developed and applied to characterize the phonon-electron scattering strength for phonon modes with different frequencies, momenta and polarizations and demonstrate solid-state thermal switching by modifying phonon-electron scattering via external photoexcitation and electrostatic gating. This CAREER project not only generates new insights for energy transfer processes in devices with high electron concentrations, but also provides transformative opportunities to develop novel functional energy materials and devices based on the interaction of microscopic energy carriers.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.