Collaborative Research: Elucidating Exciton Transport in Hierarchical Organic Materials through Time-Resolved Electronic and Vibrational Spectroscopy/Microscopy

合作研究：通过时间分辨电子和振动光谱/显微镜阐明多级有机材料中的激子传输

• 批准号: 2154449
• 负责人: Jean Hubert Olivier
• 金额: $ 28万
• 依托单位: University of Miami
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2154449&HistoricalAwards=false
• 关键词: Collaborative; Research; Elucidating; Exciton; Transport

With support from the Chemical Structure, Dynamics, and Mechanisms-A (CSDM-A) Program in the Division of Chemistry, a research team led by Erik Grumstrup at Montana State University (MSU) and Jean-Hubert Olivier at the University of Miami (UM) is investigating energy transport in light-harvesting superstructures. These organic platforms are comprised of aromatic dyes, stacked in a face-to-face conformation and then covalently “stapled” together with molecular tethers. The structural rigidity conferred by the tethers enables the construction of nanoscale objects that are structurally and electronically well-defined. By varying the physical rigidity of the tethers through synthetic chemistry, the researchers aim to show that energy transport is enhanced when the vibrations between individual molecules are reduced. To study this effect, the research team will use a variety of time-resolved spectroscopies and microscopies that allow direct imaging of energy transport through the nanostructures in the solid state. The overall scientific goal of this work is to provide a fundamental understanding of the level of disorder that can be tolerated in organic materials while still achieving long-range energy transport necessary for applications in catalysis and energy conversion. To broaden the impact of the work, the research team will develop a science communication channel on YouTube that is thematically centered on the role of chemistry in addressing contemporary problems in climate and energy and will leverage these materials to develop a co-hosted general audience seminar series at UM and MSU.Exciton diffusion lengths in organic nanostructures are often measured in the 10s of nanometers, rather than the micron length scale of inorganic semiconductors. Only a few examples of long-range exciton transport have been reported for organic materials, however these demonstrations are serendipitous, and to date, a fundamental understanding of the relevant structure-function relationships that ensure long range exciton transport is lacking. This project leverages a class of covalently tethered molecular assemblies that feature synthetic “knobs” to regulate both dynamic (electron-phonon coupling) and static heterogeneity (length of tethered dye assemblies) without changing the molecular core through which excitons are transported. Exciton transport in a series of increasingly rigidified assemblies will be measured using a variety of ultrafast spectroscopies and microscopies, both in solution and in the solid state. Experimental data from both solution and solid-state spectroscopic studies will be compared to structurally-accurate kinetic Monte Carlo models, which will be utilized to extract fundamental constraints on the structural and electronic parameters that engender long range exciton transport. Results from these combined studies will deliver new fundamental insight into: 1) how excited state properties of solvated assemblies, such as exciton delocalization and diffusion, can be tailored by tuning interchromophore rigidity, and 2) how exciton transport properties are parameterized by structural domain heterogeneity in hierarchical superstructures.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、动力学和机理计划(CSDM-A)的支持下，由蒙大拿州立大学(MSU)的Erik Grumstrup和迈阿密大学(UM)的Jean-Hubert Olivier领导的一个研究小组正在研究光收集上部结构中的能量传输。这些有机平台由芳香族染料组成，以面对面的构象堆积起来，然后用分子纽带共价“装订”在一起。由绳索赋予的结构刚性使构建结构和电子定义良好的纳米级物体成为可能。通过通过合成化学改变系链的物理刚性，研究人员的目标是表明，当单个分子之间的振动减少时，能量传输会得到加强。为了研究这种效应，研究小组将使用各种时间分辨光谱和显微镜，允许直接成像通过固体中的纳米结构的能量传输。这项工作的总体科学目标是从根本上了解有机材料中可以容忍的无序程度，同时仍然实现催化和能量转换应用所需的远程能量传输。为了扩大这项工作的影响，研究小组将在YouTube上开发一个以化学在解决当代气候和能源问题中的作用为主题的科学交流频道，并将利用这些材料在密歇根大学和密歇根大学共同主办一个普通受众研讨会系列。有机纳米结构中的激子扩散长度通常以纳米为单位测量，而不是无机半导体的微米长度。有机材料的长程激子输运只有几个例子被报道，然而这些演示是偶然的，而且到目前为止，对确保长程激子输运的相关结构-功能关系的基本理解是缺乏的。该项目利用一类以合成“旋钮”为特征的共价系留分子组件来调节动态(电子-声子耦合)和静态异质性(系留染料组件的长度)，而不改变传输激子的分子核心。将使用各种超快光谱和显微镜来测量一系列日益刚性的组件中的激子传输，无论是在溶液中还是在固体中。来自溶液和固态光谱研究的实验数据将与结构上精确的动力学蒙特卡罗模型进行比较，该模型将被用来提取对产生长程激子传输的结构和电子参数的基本约束。这些联合研究的结果将提供新的基本见解：1)如何通过调节发色团间的刚性来调整溶剂化组件的激发态性质，如激子离域和扩散，以及2)如何通过分层超结构中的结构域异质性来参数化激子传输性质。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。