Innovative Tunable Optical Properties in Nanocrystal-based Films by Employing Mechanical Instabilities

健康监测、能量存储和使用以及通信技术的未来正朝着柔性、可弯曲和可拉伸的设备发展，包括可穿戴设备和“电子皮肤”。为了实现这些应用的最大潜力，需要发现具有令人兴奋的光学和电子特性的材料，同时保留机械柔性系统的一部分。纳米晶体提出了一个理想的系统来研究这一目的，因为它们具有可调的电磁吸收和发射特性，易于制造且成本低廉，并且可以集成到可拉伸衬底上的薄膜中。尽管如此，有很少的研究，这些系统的变形行为。该奖项支持在可变形和柔性基板上创建发光纳米晶体薄膜的研究，以测量其光学和机械性能，并描述和预测这些薄膜在弯曲/拉伸过程中的行为。 这些系统的预计应用包括形成光学超材料，例如可调谐光栅和滤波器，用于身体指标的可穿戴传感器，以及柔性能源设备（例如，发光器件和太阳能光电器件）。研究方法是将机械工程、材料科学和纳米技术的思想联合收割机，以建立对纳米晶体层如何可控变形的强大理解。这项研究将被用于全年的推广活动，以激励和教育未来的工程师，包括与公众的互动和针对性的活动，为代表性不足的群体。纳米晶体，通常用于传统的刚性电子设备，有可能承受变形设备操作的应变。此外，它们可以使用环境友好的技术和材料制成，并表现出令人兴奋的尺寸依赖性，如发光。此外，由于不稳定性的形成，在预拉伸的弹性体基底上的纳米晶体薄膜中的可调谐的扭曲可以用于产生新的电磁和声学超材料。问题在于，薄膜对薄膜基底的拉伸/弯曲的机械响应几乎完全未知。本研究将致力于从实验和理论上填补这一知识空白。该研究将包括对薄膜/衬底系统中的机械行为和不稳定性形成的实验研究，这取决于薄膜的尺寸和薄膜的孔隙率/厚度。这些研究将通过系统的机械特性的理论建模来补充，以描述不稳定性的形成。 然后，该研究将被整合并用于预测和设计可拉伸电子产品，传感器和光学/声学超材料中最终应用领域的薄膜中的不稳定性。

The future of technology for health monitoring, energy storage and use, and communications is moving towards flexible, bendable, and stretchable devices, including wearable devices and "electronic skins". To reach the maximum potential of these applications, there is a need to discover materials that exhibit exciting optical and electronic properties while remaining part of a mechanically flexible system. Nanocrystals present an ideal system to investigate for this purpose, as they have tunable electromagnetic absorption and emission properties, are easy and inexpensive to make, and can be integrated into thin films on stretchable substrates. Despite this, there have been few studies on the deformation behavior of these systems. This award supports research to create thin films of luminescent nanocrystals on deformable and flexible substrates, to measure their optical and mechanical properties, and to describe and predict the behavior of these films during flexion/stretching. The projected applications of these systems include forming optical metamaterials such as tunable gratings and filters, wearable sensors for body metrics, and flexible energy devices (e.g., light-emitting devices and solar photovoltaics). The research approach is to combine ideas across mechanical engineering, materials science, and nanotechnology to create a robust understanding of how layers of nanocrystals can be controllably deformed. This research will be used in year-round outreach events to inspire and educate future engineers including interactions with the general public and targeted events for underrepresented groups.Nanocrystals, used often in traditional rigid electronic devices, have the potential to withstand the strain of deformable device operation. Moreover, they can be made using environmentally friendly techniques and materials and exhibit exciting size-dependent properties such as luminescence. In addition, tunable wrinkling, due to instability formation, in thin films of nanocrystals on pre-stretched elastomeric substrates can be used to generate new electromagnetic and acoustic meta-materials. The problem is that the mechanical responses of nanocrystal films to stretching/flexion of the film substrate are almost completely unknown. This research will be devoted to experimentally and theoretically filling this knowledge gap. The research will include experimental studies on the mechanical behavior and instability formation in nanocrystal/substrate systems, depending on nanocrystal size and film porosity/thickness. These studies will be complemented by theoretical modeling of the mechanical properties of the systems to describe the instability formation. The research will then be integrated and used for predicting and designing the instabilities in nanocrystal films with ultimate application areas in stretchable electronics, sensors, and optical/acoustic metamaterials.