Microscopic Electronic Heterogeneity Studied with Ultrafast 2D Microscopy

使用超快二维显微镜研究微观电子异质性

• 批准号: 2314378
• 负责人: Martin Zanni
• 金额: $ 56.5万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2314378&HistoricalAwards=false
• 关键词: Microscopic; Electronic; Heterogeneity; Studied; Ultrafast

With support from the Chemical Structure, Dynamics, and Mechanisms-A (CSDM-A) program in the Division of Chemistry, Professor Martin Zanni of the University of Wisconsin-Madison is developing a spatially resolved two-dimensional white-light microscope to study charge and exciton transport in perovskite microcrystals and heterogeneous thin films of semiconducting carbon nanotubes. The goal is to measure and understand the dependence of exciton and charge diffusion on microscopic heterogeneities in structural geometries and electronic couplings. These properties are important because they impact the timescale and length scales over which energy and charge moves through the material. Professor Zanni and his students will design and construct a 2D White-Light microscope in which the focus of the pump beam can be raster scanned relative to the probe. The corresponding images will give spatial maps that correlate electronic heterogeneity to exciton and charge diffusion timescales and lengths. Their studies will create a new type of hyperspectral imaging technique for ultrafast 2D spectroscopy and could lead to a better understanding of the fundamental science that links electronic structure and exciton/charge diffusion to nano-and micro-scale heterogeneities. Professor Zanni and his students funded by this grant will be involved in outreach to a local elementary school as well as build and test a novel design for an ergonomic and wheelchair accessible laser table. The electronic structure of organic and inorganic films and crystals dictates the timescale and length of exciton and charge diffusion. Inherent to solution processed materials are micro- and nanoscale heterogeneities that alter electronic structure. Using a new microscope built from an ultrafast 2D white-light spectrometer, the Zanni research group discovered spatial patterns of microscopic heterogeneities in electronic structure within single microcrystals across a variety of materials. In two different types of singlet fission materials, changes were observed in bandgap near edges, defects, and in appreciable quantities throughout the bulk material. In 2D perovskites, micron spatial variations in the binding energy of biexcitons were observed. With these observations in mind, it stands to reason that a crystal that has spatially heterogeneous electronic structure should also have spatially dependent exciton diffusion. The purpose of this proposal is to test that hypothesis by studying the link between electronic heterogeneity and exciton/charge diffusion on the micron length scale within microcrystals and domains of thin films. To do so, a new version of the 2D White-Light microscope will be built in which the focus of the pump beam can be raster scanned relative to the probe. Using this new microscope, the ultrafast dynamics in singlet fission and 2D perovskite microcrystals will be measured as will purposely engineered thin films of semiconducting carbon nanotubes. The images will give spatial maps that correlate electronic heterogeneity to exciton and charge diffusion lengths. By building a new type of ultrafast microscope and pursuing the aims of this proposal, the Zanni team aims to build a better understanding of how exciton and charge diffusion is dictated by heterogeneity in electronic structure on sub-crystallin and sub-domain length scales.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.

在化学系化学结构，动力学和机制-A（CSDM-A）计划的支持下，威斯康星大学麦迪逊分校的Martin Zanni教授正在开发一种空间分辨二维白光显微镜，以研究钙钛矿微晶和半导体碳纳米管异质薄膜中的电荷和激子传输。目标是测量和理解激子和电荷扩散对结构几何形状和电子耦合中微观不均匀性的依赖性。这些性质很重要，因为它们影响能量和电荷通过材料的时间尺度和长度尺度。Zanni教授和他的学生将设计和建造一个2D白光显微镜，其中泵浦光束的焦点可以相对于探头进行光栅扫描。相应的图像将给出空间映射，将电子异质性与激子和电荷扩散的时间尺度和长度联系起来。他们的研究将为超快2D光谱学创造一种新型的高光谱成像技术，并可能导致更好地理解将电子结构和激子/电荷扩散与纳米和微米尺度异质性联系起来的基础科学。Zanni教授和他的学生将参与到当地一所小学的外展活动中，并为符合人体工程学和轮椅无障碍的激光工作台构建和测试一种新颖的设计。有机和无机薄膜和晶体的电子结构决定了激子和电荷扩散的时间尺度和长度。溶液处理材料固有的是改变电子结构的微米和纳米级异质性。Zanni研究小组使用由超快2D白光光谱仪构建的新显微镜，发现了各种材料中单个微晶内电子结构的微观不均匀性的空间模式。在两种不同类型的单重态裂变材料中，观察到边缘附近的带隙、缺陷和整个大块材料中可观的量的变化。在2D钙钛矿中，观察到双激子的结合能的微米空间变化。考虑到这些观察结果，具有空间异质电子结构的晶体也应该具有空间依赖的激子扩散。本提案的目的是通过研究微晶和薄膜领域内微米长度尺度上的电子异质性和激子/电荷扩散之间的联系来验证这一假设。为此，将建立一个新版本的2D白光显微镜，其中泵浦光束的焦点可以相对于探头进行光栅扫描。使用这种新的显微镜，将测量单线态裂变和2D钙钛矿微晶的超快动力学，以及特意设计的半导体碳纳米管薄膜。这些图像将给出电子异质性与激子和电荷扩散长度相关的空间图。通过建立一种新型的超快显微镜和追求这一建议的目标，Zanni团队旨在更好地理解激子和电荷扩散是如何由亚晶体和亚畴长度尺度上的电子结构的异质性决定的。这个奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持的。