EAGER: Enhancement of Piezoelectric Properties in two-dimensional materials and its application

非技术性的：压电是由雅克和皮埃尔·居里于1880年发现的。这种特性允许材料将机械应力转换为电信号，反之亦然。压电器件在医学、航空航天、交通运输和消费电子等领域有着重要的应用。例如，压电元件被用作移动的电话的压力传感器和用于监测内燃机中的燃烧。对于未来的应用，传感器应该在纳米级或微米级水平上工作，灵活透明，易于与传统电子产品集成。该项目将研究新型二维（2D）材料中的压电性，旨在实现下一代器件。2D材料具有原子厚度，具有独特的光学和电学特性。它们的压电特性可用于实现机械供电的透明柔性电荷产生装置。 该项目将使在微尺度和纳米尺度的创新设备的制造在医学，工业，环境工程，和消费电子产品前所未有的应用。技术：材料中的压电性能是由于非中心对称结构的材料晶体结构。还已知的是，一些材料在其体结构中是非压电的。然而，当它们被减薄成单层或多层时，它们表现出压电性。在这项工作中，二维材料的压电性能进行了研究。提出了一种增强二维弱压电材料压电性能的新方法。表面声波（SAW）用于增强2D材料的压电性能。声表面波器件将建立在强压电材料的岛上。行波会对放置在基片上的二维材料产生应力和应变，从而提高二维材料的压电性能。使用表面声波（SAW）来激活耦合到弱压电材料并引起弱压电材料的压电系数变化的声波的技术是新颖的。在这项工作中，我们计划将这种技术应用到几个二维材料和测量改进的压电系数及其应用，如在传感器。本研究所提出的方法大大提高了二维材料的压电效应，并消除了文献中报道的其他技术的缺点。现有方法的缺点包括制造复杂度和精度要求高、成本高以及2D材料的堆叠层数量的限制。不同的2D材料，如二硫化钼（MoS2）和硒化铟（InSe）将被测试和评估，包括那些常用的和较少研究的材料。该研究成果将极大地扩展二维材料压电性的应用范围，并将成为电子、机电、传感器、光电领域中更加实用和新颖的器件。该奖项体现了NSF的法定使命，通过基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical:Piezoelectricity was discovered in 1880 by Jacques and Pierre Curie. This property allows materials to convert mechanical stress into electrical signals and vice versa. Piezoelectric devices have important applications in medicine, aerospace, transportation and consumer electronics. For example, piezoelectric elements are used as pressure sensors mobile phones and to monitor combustion in internal combustion engines. For future applications, sensors should operate at nanoscale or microscale level, be flexible and transparent, and easy to integrate with conventional electronics. This project will investigate piezoelectricity in novel two-dimensional (2D) materials, with the aim of realizing next generation devices. 2D materials are atomically thick and have unique optical and electrical properties. Their piezoelectric properties could be used realize mechanically powered transparent flexible charge-generating devices. This project will enable the fabrication of innovative devices at the microscale and nanoscale with unprecedented applications in medicine, industry, environmental engineering, and consumer electronics.Technical:Piezoelectric properties in materials are due to non-centrosymmetric structure of the material crystal structure. It is also known that some materials are non-piezoelectric in their bulk structure. However, when they are thinned in monolayer or several layers, they show piezoelectricity properties. In this work the piezoelectric properties for 2D materials are studied. It presents a novel technique for enhancement of piezoelectric properties in weak piezoelectric two-dimensional materials. Surface Acoustic Waves (SAW) are used to enhance the piezoelectric properties of 2D materials. The SAW device will be built on an island of strong Piezoelectric material. The traveling acoustic wave would cause stress and strain on the two-dimensional materials placed on the substrate, which would increase the piezoelectric properties of the two-dimensional materials. The technique of using Surface Acoustic Waves (SAW) to activate acoustic waves that couple to the weak piezoelectric material and cause changes in the piezoelectric coefficient of the weak piezoelectric material is novel. In this work we are planning to apply this technique to several two-dimensional materials and measure improved piezoelectric coefficients and their applications, such as in sensors. The proposed method in this research greatly enhances the piezoelectric effect of 2D materials and eliminates the disadvantages of other techniques reported in the literature. The drawbacks in current methods include high demand of fabrication complexity and precision, high cost, and the limitation of the number of stacked layers of 2D materials. Different 2D materials such as molybdenum disulfide (MoS2) and indium selenide (InSe) will be tested and evaluated, including those commonly used and less-studied ones. The outcome of this proposed work will largely extend the utilization range of piezoelectricity of 2D materials, and will turn into more practical and novel devices in electronic, electromechanical, sensors, and optoelectronic fields.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.