Excitonic electroabsorption effects in macroscopically aligned carbon nanotubes

碳纳米管作为一种具有实现下一代光电器件潜力的纳米材料，已经引起了人们的极大兴趣。在外加电场作用下，单个纳米管的光吸收会发生强烈变化，这种现象被称为电吸收。这使它们成为高速电光调制器的有希望的候选者，这是光通信，计算和量子信息处理等应用的关键组件。利用纳米管特性的关键是将大量纳米管排列到宏观尺度上。本项目将使用智能自主自组装系统来实现宏观排列的半导体碳纳米管薄膜，然后研究其电光特性。该项目的研究成果可能会导致新的材料平台，并为未来的技术奠定基础。PI还将通过实验室、课堂和外展项目的培训和教育活动，努力扩大STEM的参与。这些活动的目标是培养多样化的未来STEM劳动力。技术描述传统体半导体中的电吸收导致弱光调制，需要大的驱动电场和开关能量，并且对温度变化敏感。半导体量子阱可以解决前两个挑战，但仍然受到敏感的温度依赖性的影响，需要复杂的制造和工程，有时还需要低温设备操作。纳米材料是一种高性能、多用途、易于制造的新型室温材料平台。然而，目前在宏观材料中的电吸收效应的证明是有限的。本项目主要通过直接实验光谱学的方法，证明在静电场驱动下，由自组装系统制备的高度排列和密集排列的单型半导体碳纳米管宏观薄膜中的激子电吸收效应。本项目的目标是建立这种宏观碳纳米管集成体的制造平台，并探索其电吸收效应的光谱学证据。具体来说，首席研究员开发了一种闭环，自动和机器学习辅助的真空过滤系统，用于制造排列单电子型碳纳米管的宏观薄膜。此外，首席研究员还进行了光谱学研究，以探索几种具有代表性的不同直径的半导体碳纳米管排列薄膜的电吸收效应。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。

Non-technical Description Carbon nanotubes have gained tremendous interest as a nanomaterial with potential to enable next generation optoelectronic devices. Individual nanotubes have a strong change in light absorption under an applied electric field, a phenomenon called electroabsorption. This makes them a promising candidate for high-speed electro-optic modulators, crucial components for applications such as optical communication, computing, and quantum information processing. Key to leveraging nanotube properties will be to align large numbers of them up to macroscopic scales. This project will use an intelligent autonomous self-assembly system to achieve macroscopically aligned semiconducting carbon nanotube films and then study their electro-optical properties. The research findings from this project could lead to a new material platform and lay the foundation for future technologies. The PI will also work to expand participation in STEM through training and education activities in the laboratory, classroom, and through outreach programs. The goal of these activities is to develop a diverse future STEM workforce. Technical DescriptionElectroabsorption in conventional bulk semiconductors result in weak optical modulation, requiring large driving electric field and switching energy, and are sensitive to temperature variations. Semiconductor quantum wells can address first two challenges but still suffer from sensitive temperature dependency, require sophisticated manufacturing and engineering, and sometimes cryogenic device operations. Nanomaterials are emerging as new high-performance, versatile, and easy-to-manufacture room-temperature material platforms. However, current demonstrations of electroabsorption effects in macroscopic materials are limited. This project focuses on the direct experimental optical spectroscopy demonstration of the excitonic electroabsorption effects in macroscopic films of highly aligned and densely packed single-type semiconducting carbon nanotubes, which are manufactured through a self-assembly system and driven under static electric field. The goal of this project is to establish the manufacturing platform of such macroscopic carbon nanotube ensembles and explore the optical spectroscopy evidence of their electroabsorption effects. Specifically, the principal investigator develops a closed-loop, automatic, and machine-learning-assisted vacuum filtration system toward the fabrication of macroscopic films of aligned single-electronic-type carbon nanotubes. In addition, the principal investigator performs optical spectroscopy studies to explore electroabsorption effects in aligned films of a few representative semiconducting carbon nanotubes with different diameters.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.