EAGER: Micro and Nanoscale Thin Film Pyroelectric Materials via Strain Engineering

由于热能的无处不在和丰富，人们研究和开发了许多材料、结构和策略来利用热能。在首选自供电设备的应用中(例如，生物植入设备和外星野外机器人)，需要通过小型设备从周围环境中收集废热能量的能力。微米和纳米级的热释电材料和设备是一种可能的解决方案，因为它们可以将微小而不规则的温度波动转化为电能。然而，它们极低的功率密度是阻碍其实际应用的主要障碍。这一早期概念探索性研究(AGER)奖支持通过弹性应变工程设计、制造和实现技术上有用的微米和纳米级热能到电能转换材料和设备的研究。这项研究对可持续能源收集的环境友好型热设备的开发具有潜在的广泛影响。这项研究有可能在清洁能源领域造福美国经济。此外，研究人员将通过展示用于能量转换的纳米设备来接触当地高中的K-12学生。这项研究的目标是探索一种具有巨大热电特性的潜在变革性微纳尺度热释电杂化薄膜材料。创新的关键概念是将具有巨大晶格膨胀/收缩的强关联氧化物的超快热相变转移到传统的热释电材料上。这种材料的热释电系数预计将比传统热释电材料高两到三个数量级。具体目的是展示高质量热释电VO2/ZnO杂化薄膜系统的制备，并表征这些材料和结构中的高性能指标。PI将通过射频溅射和光学光刻来制备材料和结构，并测试各个组件的热释电性能和杂化材料的合成功能和性能。PI将探索混合动力车在热释电系数、功绩系数和功率密度方面的高材料指标的上限。这些活动将由计算建模工作来设计和指导。这项工作的学术意义包括：对热释电材料独特的设计和工作机制的新理解；对耦合过程的定量理解和建模，包括超快相变、热流、应变/应力和电极化。

As thermal energy is ubiquitous and abundant, many materials, structures, and strategies have been studied and developed to harness heat energy. In applications where self-powered devices are preferred (for example, bio-implanted devices and extraterrestrial field robots), the ability to harvest the waste thermal energy from the ambient environment by small devices is needed. Micro and nanoscale pyroelectric materials and devices are one possible solution, as they can convert small and irregular temperature fluctuations into electricity. However, their extremely low power density is a major obstacle preventing practical applications. This EArly-concept Grant for Exploratory Research (EAGER) award supports research on designing, fabricating and achieving technologically useful micro and nanoscale thermal-to-electrical energy conversion materials and devices by elastic strain engineering. The research has potentially broad impacts on the development of environmentally-friendly thermal devices for sustainable energy harvesting. This research has potential to benefit the US economy in the sector of clean energy. In addition, the researchers will to reach out to K-12 students at local high schools through the demonstration of nanodevices for energy conversion.The objective of this research is to explore a potentially transformative micro and nanoscale pyroelectric hybrid thin film material with giant thermoelectric Figure of Merit. The innovative key concept is the transfer of the ultrafast thermal phase transition of strongly correlated oxides with colossal lattice dilation/contraction to conventional pyroelectric material. The material's pyroelectric coefficient is expected to be two to three orders of magnitude higher than conventional pyroelectrics. Specific aims are to demonstrate the fabrication of high-quality pyroelectric VO2/ZnO hybrid thin film system, and characterize the high Figure of Merit metrics in these materials and structures. The PIs will fabricate the materials and structures by radio frequency sputtering and optical lithography, and test the individual components' pyroelectric properties and the hybrid material's synthetic functionalities and performances. The PIs will explore the upper limit of the hybrid's high materials metrics in terms of pyroelectric coefficient, Figure of Merit, and power density. These activities will be designed and guided by computational modeling efforts. The intellectual significance of the work includes: new understanding on the unique design and working mechanism of pyroelectric materials; quantitative understanding and modeling of coupled processes including ultrafast phase transition, heat flow, strain/stress, and electrical polarization.