Imaging and manipulating inter-particle interactions in van der Waals materials

电子和光子技术，从现代激光器到计算机和太阳能电池，依赖于高能粒子的有效传输和转换，例如电子，激子（中性正负电荷对），声子（热载体）和光子（光）。在几乎所有的材料中，这些高能粒子共存并相互作用。无意的粒子间相互作用对现代设备的操作非常有害：例如，电子-声子相互作用是计算机芯片和太阳能电池板中的主要效率损失机制。尽管如此，如果这些相互作用可以被定制和有益地利用，它们可以在下一代电子，光子和信息技术中解锁大规模的效率改进和新功能。在这个项目中，PI和他的团队正在开发一种新的超灵敏光学显微镜，以直接成像和操纵各种材料中的粒子间相互作用。研究重点是二维半导体，其中粒子相互作用显着增强。该项目的目标是成像新兴电子材料中的电子-激子和激子-声子相互作用，并使用光操纵这些相互作用。这项研究将为实现多功能电子和光子平台带来新的方法，这些平台可以快速重新配置，并具有非凡的能量传输特性。更广泛的目标包括促进学术和工业实验室广泛采用该团队的新成像方法，这些实验室有兴趣通过发布广泛的仪器蓝图来开发具有定制能量传输特性的材料，以及发布一个宣传视频，展示一名研究生在显微镜上进行完整的实验循环，以揭开最先进仪器的科学过程的神秘面纱。半导体中电子、激子和声子之间的体相互作用可以抑制或增强能量传输几个数量级，并触发像超导性这样的奇异相。这些效应在低维货车德瓦尔斯半导体中可能特别强，其中减小的体积、量子限制和介电限制都促进了强的粒子间相互作用。虽然它们被认为发挥着至关重要的功能作用，但这些相互作用发生在极短的时间和长度尺度上，使它们非常难以研究。PI和他的团队正在开发超灵敏、超快的光学散射显微镜，以独特的方式跟踪纳米尺度上真实的空间中的多个光激发高能粒子及其相互作用。该项目涉及超灵敏散射显微镜的推广，以在广泛的温度范围内实现各种材料中的单粒子灵敏度。利用这种独特的工具，研究小组专注于成像和操纵过渡金属二硫族化物半导体中的电子-激子相互作用以及超原子组件中的激子-声子相互作用。在这两种情况下，该项目旨在创建多功能材料平台，可以通过微调热和介电环境或使用超快光脉冲等外部刺激来扰动粒子间的相互作用来重新配置。通过对货车德瓦尔斯材料中多体相互作用的深入理解，该团队寻求建立对远距离能量传输和转换的新型主动控制，这些材料将成为下一代电子产品的关键组成部分。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值进行评估，被认为值得支持和更广泛的影响审查标准。

Non-technical summaryElectronic and photonic technologies, from modern lasers to computers and solar cells, rely on the efficient transport and conversion of energetic particles such as electrons, excitons (neutral pairs of negative and positive charges), phonons (heat carriers), and photons (light). In almost all materials, these energetic particles co-exist and interact with one another. Unintentional inter-particle interactions are highly detrimental to modern device operation: for example, electron–phonon interactions are the primary efficiency loss mechanism in computer chips and solar panels. Nevertheless, if these interactions can be tailored and beneficially exploited, they can unlock massive efficiency improvements and new functionality in next-generation electronic, photonic and information technologies. In this project, the PI and his group are developing a new ultra-sensitive optical microscope to directly image and manipulate inter-particle interactions in a wide range of materials. The research focuses on two-dimensional semiconductors wherein particle interactions are dramatically enhanced. The goal of the project is to image electron–exciton and exciton–phonon interactions in emerging electronic materials, and to manipulate these interactions using light. This research should lead to new approaches for realizing multi-functional electronic and photonic platforms that can be rapidly reconfigured and that boast extraordinary energy transport properties. Broader goals include facilitating wide adoption of the team’s new imaging approach by academic and industrial laboratories interested in developing materials with tailored energy transport properties by publishing extensive instrument blueprints, as well as posting an outreach video displaying a graduate student performing a full experimental cycle on the microscope to demystify the scientific process on state-of-the-art instrumentation.Technical summaryMany-body interactions between electrons, excitons and phonons in semiconductors can suppress or enhance energy transport by orders of magnitude, and trigger exotic phases like superconductivity. These effects can be particularly strong in low-dimensional van der Waals semiconductors, where reduced volumes, quantum confinement and dielectric confinement all promote strong inter-particle interactions. Although they are known to play a crucial functional role, these interactions occur on extremely short time- and length-scales, making them notoriously difficult to study. The PI and his group are developing ultrasensitive, ultrafast optical scattering microscopes that uniquely track multiple photoexcited energetic particles and their interactions in real space on nanometer scales. This project involves the generalization of ultrasensitive scattering microscopy to reach single-particle sensitivity in a variety of materials over a broad range of temperatures. Using this unique tool, the research team focuses on imaging and manipulating electron–exciton interactions in transition metal dichalcogenides semiconductors and exciton–phonon interactions in superatomic assemblies. In both cases, the project seeks to create multi-functional material platforms that can be reconfigured by perturbing inter-particle interactions through fine-tuning of thermal and dielectric environments, or using external stimuli such as ultrafast light pulses. Through a much-refined understanding of many-body interactions in van der Waals materials, the team seeks to establish new forms of active control over long-range energy transport and conversion in classes of materials that will be key building blocks of next-generation electronic, photonic and information technologies.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.