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核心地位。虽然无缺陷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优越。这项拨款支持研究如何将有机半导体晶体制造成扭曲的编织网络，这种扭曲的编织网络在电子传输、探测和发射不同类型的光方面的表现优于单晶。这些扭曲的晶体是由熔体形成的，这使得利用高通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、晶体管以及用于传感和健康监测的可穿戴电子设备的塑料电子工业，从而扩大了美国经济。在固态物理，材料科学和工艺工程的交叉点，这一多学科研究为本科生和研究生提供了丰富的培训平台，为CHIPS和科学法案所要求的劳动力发展做出了贡献。扭曲晶体创造的彩色图案构成了K-12级互动STEAM工作室的基础。通过这个活动，学生们了解了晶体和光物质相互作用的概念。手电子材料的设计依赖于手性分子的对映选择性合成或对映体的外消旋混合物的劳动和原子密集的分辨率。熔体自发形成的扭曲晶体可以表现出中尺度的热带性质。在chiroptoelectronics中，扭曲晶体的发展面临的挑战是缺乏对扭曲感和方向的空间控制，以及当前批量加工与高通量制造的不兼容性。本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薄膜。研究了混合螺杆挤压和卷对卷涂覆熔融材料成图案薄膜的可扩展制造方法。这种连续加工方法包括在挤压前对分子化合物和扭转添加剂进行在线混合；精确控制薄膜厚度，结晶温度，剪切轮廓；和可调图案使用瓦楞辊。新开发的用于薄膜涂层在线表征的快速微分偏振成像允许筛选和优化数百种由准直扭曲晶体薄膜制成的电光薄膜。扭曲晶体应用的例子是圆偏振光探测器和波导。该奖项反映了美国国家科学基金会的法定使命，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.