Patterning Mesoscale Chirality by Guided Crystal Twisting

用于计算机芯片和太阳能电池板的硅基半导体晶体集中体现了我们对晶体材料的依赖，并强调了它们在信息技术和可再生能源中的中心地位。虽然无缺陷的单晶是大多数应用的黄金标准，但在某些情况下，不完美的相互作用晶体束可能更上级。这项资助支持研究如何将有机半导体晶体制造成扭曲的编织物网络，这些编织物在电子传输以及检测和发射不同类型的光方面违反直觉地优于单晶。这些扭曲的晶体由熔体形成，使得利用高产量制造方法成为可能。这些新型材料支持基于柔性发光二极管和显示器、晶体管的塑料电子行业，以及用于传感和健康监测的可穿戴电子产品，从而增强了美国经济。在固态物理，材料科学和过程工程的交叉点，这个多学科的研究作为本科生和研究生的丰富的培训平台，有助于劳动力发展所要求的CHIPS和科学法案。由扭曲的水晶创造的彩色图案构成了K-12级别互动式STEAM研讨会的基础。通过这项活动，学生们了解晶体和光物质相互作用的概念。设计手性电子学材料依赖于手性分子的对映选择性合成或对映异构体外消旋混合物的劳动密集型和原子密集型拆分。从熔体中自发形成的扭曲晶体可以表现出介观旋光性质。用于手电子学的扭曲晶体的进步所面临的挑战是缺乏对扭曲方向和方向的空间控制，以及当前批量处理与高吞吐量制造的不兼容性。这项研究阐明了扭曲晶体形成的机制以及晶体纤维的组织如何影响电子和光子的传输。这种理解指导了可扩展的加工方法的发展，以制造具有规定取向和扭曲感的扭曲晶体膜。混合螺杆挤出和辊对辊涂布熔融材料成图案化的膜作为这些chiroptoelectronic材料的可扩展的制造方法进行了研究。这种连续加工方法包括在挤出前在线混合分子化合物和加捻添加剂;精确控制薄膜厚度、结晶温度和剪切曲线;以及使用波纹辊进行可调图案化。新开发的快速差分偏振成像在线表征镀膜过程中允许筛选和优化的准直扭曲晶体薄膜制成的电光薄膜数百。扭曲晶体的应用实例包括圆偏振光探测器和波导。该奖项反映了NSF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。

Silicon-based semiconductor crystals for computer chips and solar panels epitomize our reliance on crystalline materials and underscore their centrality for information technologies and renewable energies. While defect-free single crystals are the gold standard for most applications, bundles of imperfect, interacting crystals can be superior in some cases. This grant supports research on how organic semiconductor crystals can be fabricated as networks of twisted braids that counterintuitively outperform single crystals in the transport of electrons and detection and emission of different types of light. These twisted crystals are formed from the melt, making it possible to leverage high throughput fabrication methods. These novel materials support plastic electronics industries based on flexible light emitting diodes and displays, transistors, and wearable electronics for sensing and health monitoring thus augmenting the U.S. economy. At the intersection of solid-state physics, materials science, and process engineering, this multidisciplinary research serves as a rich training platform for undergraduate and graduate students, contributing to workforce development as called for by the CHIPS and Science Act. The colorful patterns created by twisted crystals form the basis of interactive STEAM workshops at the K-12 level. Through this activity, students learn about the concepts of crystals and light-matter interactions.Designing materials for chiroptoelectronics has relied on the synthesis of chiral molecules enantioselectively or the labor- and atom-intensive resolution of racemic mixtures of enantiomers. Twisted crystals that form spontaneously from the melt can manifest mesoscale chiroptical properties. The challenges facing the advancement of twisted crystals for chiroptoelectronics are the lack of spatial control over the twist sense and direction, and the incompatibility of current batch processing with high throughput manufacturing. This research articulates mechanisms governing twisted crystal formation and how the organization of crystal fibers affects electron and photon transport. This understanding guides the development of scalable processing methods to fabricate twisted crystal films with prescribed orientations and twist sense. Hybrid screw extrusion and roll-to-roll coating of molten material into patterned films are investigated as a scalable manufacturing method for these chiroptoelectronic materials. This continuous processing method involves inline mixing of molecular compounds and twisting additives prior to extrusion; precise control over film thickness, crystallization temperature, and shear profile; and tunable patterning using corrugated rollers. Newly developed rapid differential polarization imaging for inline characterization during film coating permits the screening and optimization of hundreds of electro-optical thin films made of collimated twisted crystal films. Examples of the applications of twisted crystals are circularly polarized light detectors and waveguides.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.