Collaborative Research: EAGER: Enhancing Pyroelectric Effects in Nanostructured Materials for High-Efficiency Energy Conversion

合作研究：EAGER：增强纳米结构材料的热释电效应以实现高效能量转换

• 批准号: 1549942
• 负责人: Alexander Balandin
• 金额: $ 7.5万
• 依托单位: University of California-Riverside
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1549942&HistoricalAwards=false
• 关键词: Collaborative; Research; EAGER; Enhancing; Pyroelectric

A large amount of energy is lost as waste heat in many engineering systems such as automobiles and turbomachinery. Significant energy gains may be obtained by efficiently scavenging such waste heat through appropriate energy conversion mechanisms. One particularly promising opportunity lies in the conversion of temperature gradients in time into electricity, referred to as the pyroelectric effect. This project will utilize experiments and theoretical modeling to explore the pyroelectric effect in nanowires, and will build prototype pyroelectric-based energy harvesting microdevices. Research will help understand the nature of pyroelectric effect in nanowires, including the amount of energy that may be realistically harvested from nanowire based devices, performance limits, etc. which will help guide further development of potential energy conversion devices. All three institutions involved in this collaborative research are minority serving institutions located in highly populated Hispanic areas. PIs will leverage this opportunity to excite and recruit minority and women students to the emerging nano/microscale energy harvesting area. The PIs will carry out outreach to local high schools to excite K-12 students about energy harvesting, and encourage them to consider further STEM education and careers.The technical goal of this combined experimental and theoretical-simulation research is to measure and characterize the pyroelectric effect in nanowires (GaN, ZnO, etc.) for developing micro- and nano-scale devices for thermal energy harvesting and sensors applications. Despite its potential to convert waste heat into usable electricity, the pyroelectric effect has been largely unexplored, in particular at the micro/nanoscale. This is partially due to lack of methodologies for characterization of this effect at small scales. Recent theoretical findings suggest a dramatically higher pyroelectric coefficient in nanowires, similar to enhancements observed in thermoelectric and piezoelectric performance of nanowires, albeit this prediction has not been confirmed experimentally. In this effort, a methodology based on microfabricated devices will be developed to quantitatively measure and characterize the pyroelectric properties of individual suspended nanowires. In addition, theoretical models and computational tools will be developed for (i) interpretation and analysis of the experimental pyroelectric data; (ii) prediction of the pyroelectric response of various nanostructured materials (individual nanowires; nanowires arrays); and (iii) optimization of the nanostructure parameters (material composition, size, shape, interface) for enhancing the pyroelectric voltage. The proposed models will include strong non-uniformity of the polarization distribution in nanostructures and possible phonon and electron confinement effects. Based on the learning from experiment and theory, prototype pyroelectric-based energy harvesting microdevices will be built using a single and an array of nanowires. Experimental data on pyroelectric coefficient of nanowires and dependence on nanowire size, temperature, etc. will contribute to the fundamental understanding of this effect. A fundamental understanding of pyroelectric transport in single nanowires may lead to a new paradigm of high efficiency energy conversion devices that take advantage of nanoscale engineering of materials to optimize pyroelectric performance.

在汽车和涡轮机械等许多工程系统中，大量能量以废热的形式损失掉。通过适当的能量转换机制有效地清除此类废热可以获得显着的能量增益。一个特别有前途的机会在于将温度梯度及时转化为电能，称为热释电效应。该项目将利用实验和理论模型来探索纳米线中的热释电效应，并将构建基于热释电的能量收集微型器件原型。研究将有助于了解纳米线中热释电效应的本质，包括可以从基于纳米线的设备中实际收获的能量量、性能限制等，这将有助于指导势能转换设备的进一步开发。参与这项合作研究的所有三个机构都是位于人口稠密的西班牙裔地区的少数族裔服务机构。 PI 将利用这个机会来激励和招募少数族裔和女学生进入新兴的纳米/微米能量收集领域。 PI 将向当地高中开展推广活动，激发 K-12 学生对能量收集的兴趣，并鼓励他们考虑进一步的 STEM 教育和职业。这项实验和理论模拟相结合的研究的技术目标是测量和表征热释电纳米线（GaN、ZnO 等）的效应，用于开发用于热能收集和传感器应用的微米级和纳米级器件。尽管热释电效应具有将废热转化为可用电力的潜力，但它在很大程度上尚未被探索，特别是在微/纳米尺度上。部分原因是缺乏小规模表征这种效应的方法。最近的理论研究结果表明，纳米线的热电系数显着提高，类似于观察到的纳米线热电和压电性能的增强，尽管这一预测尚未得到实验证实。在这项工作中，将开发一种基于微制造设备的方法来定量测量和表征单个悬浮纳米线的热释电特性。此外，还将开发理论模型和计算工具，用于（i）实验热释电数据的解释和分析； (ii) 预测各种纳米结构材料（单个纳米线；纳米线阵列）的热释电响应； (iii)优化纳米结构参数（材料成分、尺寸、形状、界面）以增强热释电电压。所提出的模型将包括纳米结构中极化分布的强烈不均匀性以及可能的声子和电子限制效应。基于实验和理论的学习，将使用单根纳米线和纳米线阵列构建基于热释电的能量收集微型器件原型。关于纳米线热电系数以及对纳米线尺寸、温度等的依赖性的实验数据将有助于从根本上理解这种效应。对单纳米线中热释电传输的基本理解可能会带来高效能量转换装置的新范例，该装置利用材料的纳米级工程来优化热释电性能。