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

非技术概述从现代激光到计算机和太阳能电池的电子和光子技术，依赖于电子、激子(中性正负电荷对)、声子(热载体)和光子(光)等高能粒子的有效传输和转换。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运行是非常有害的：例如，电子-声子相互作用是计算机芯片和太阳能电池板的主要效率损失机制。然而，如果这些相互作用能够被量身定做并有益地利用，它们可以在下一代电子、光子和信息技术中释放出巨大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颗粒间相互作用。这项研究的重点是二维半导体，其中粒子的相互作用大大增强。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，并利用光来操纵这些相互作用。这项研究应该会导致实现多功能电子和光子平台的新方法，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，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，以及发布一段延伸视频，展示一名研究生在显微镜上执行完整的实验周期，以揭开最先进仪器的科学过程的神秘面纱。技术概述半导体中电子、激子和声子之间的多体相互作用可以抑制或增强能量传输数量级，并引发超导等奇异阶段。这些效应在低维范德华半导体中可能尤其强烈，在这些半导体中，减小的体积、量子限制和介电限制都会促进强烈的粒子间相互作用。尽管已知它们起着关键的功能作用，但这些相互作用发生的时间和长度都非常短，这使得对它们的研究变得非常困难。PI和他的团队正在开发超灵敏、超快的光学散射显微镜，这种显微镜可以在纳米尺度上独特地跟踪多个光激发的高能粒子及其在真实空间中的相互作用。该项目包括推广超灵敏散射显微镜，以在广泛的温度范围内实现对各种材料的单粒子灵敏度。使用这一独特的工具，研究小组专注于成像和操作过渡金属二卤化物半导体中的电子-激子相互作用以及超原子组装中的激子-声子相互作用。在这两种情况下，该项目都寻求创建多功能材料平台，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乱粒子间的相互作用，从而重新配置这些平台。通过对范德华材料中多体相互作用的深入了解，该团队寻求在材料类别中建立对远程能量传输和转换的新形式的主动控制，这些材料将成为下一代电子、光子和信息技术的关键组成部分。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.