A New Look at Classic Materials Systems: Advanced Synchrotron X-ray Characterization of Colloidal Nanocrystals

经典材料系统的新视角：胶体纳米晶体的先进同步加速器 X 射线表征

基本信息

批准号：
1708617
负责人：
Sharmila Mukhopadhyay
金额：
$ 30.75万
依托单位：
University of Maine
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-07-01 至 2021-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1708617&HistoricalAwards=false
关键词：
New Look Classic Materials Systems

项目摘要

Nontechnical Abstract:Although semiconductor nanocrystals (NCs) show great promise for applications in photovoltaics, solid state lighting, and nanoscale electronics, the success of the assembled devices will be determined primarily on how well an assembly of NCs can conduct electricity. The conventional experimental probes used to characterize these systems typically do not explore techniques that are either sensitive to the atomic species or that are performed in situ. It is imperative, therefore, to identify new experimental probes that can provide crucial information on NCs that cannot be achieved via other methods. This project, supported by the Solid State and Materials Chemistry program at NSF, employs state-of-the-art x-ray characterization methods to elucidate a wide range of unanswered problems in the NC literature, including the mechanism of cation exchange in NCs and effects of ligand chemistry on charge carrier dynamics in NCs. The project focuses on both operando/in situ soft and hard x-ray absorption spectroscopy and well as ultra-fast x-ray absorption spectroscopy. These techniques, for the most part, have not been exploited to probe the chemistry and physics of semiconductor NCs and it is anticipated that they will provide crucial insight to answer important questions regarding the bonding and charge transfer dynamics in these materials. In turn, the results from this research proposal will have a strong impact on the ability to fabricate next generation nano-electronic materials. This research leverages the vast infrastructure within the Laboratory for Surface Science and Technology (LASST), an interdisciplinary center that brings together researchers from Physics, Chemistry, Electrical & Computer Engineering, and Chemical & Biological Engineering. This research project provides advanced graduate training in the fields of physics, chemistry, and materials science, specifically in ultra-high vacuum surface science and materials characterization including synchrotron research at the Advanced Light Source and Advanced Photon Source. In addition, the research laboratory, which is housed in LASST, is on display via tours and will introduce many underprivileged students, including a substantial Native American population, to cutting edge instrumental tools. Technical Abstract:This project, supported by the Solid State and Materials Chemistry program at NSF, provides an unprecedented look into the fundamental mechanisms behind processes such as charge transport and cation exchange in semiconductor nanocrystals (NCs). The research activities focus on both operando/in situ soft and hard x-ray absorption spectroscopy and well as ultra-fast x-ray absorption spectroscopy. These techniques, for the most part, have not been exploited to probe the chemistry and physics of semiconductor NCs and it is anticipated that they will provide crucial insight to answer important questions regarding the bonding and charge transfer dynamics in these materials. In turn, the results from this research proposal will have a strong impact on the ability to fabricate next generation nano-electronic materials. The transformative feature of this work is the use of cutting-edge x-ray techniques to probe NCs in their most common environment: solution phase. Armed with the knowledge that the interplay between controlling carrier densities and mobilities in NCs will play a strong role in making highly conductive NC devices, the project research objectives focus on two related research thrust areas: (a) in situ x-ray spectroscopy of NC materials undergoing cation exchange processes and (b) effects of surface ligands on the interfacial charge carrier dynamics in NCs as probed by ultrafast x-ray spectroscopy. Materials of systems of interest include CdSe as the archetypal nanomaterial. The general mechanisms that are investigated, however, will lead to the study of new materials, such as other binary semiconductors like PbSe or metallic nanostructures such as Ag or Pb. This research project provides advanced graduate training in the fields of physics, chemistry, and materials science, specifically in ultra-high vacuum surface science and materials characterization including synchrotron research at the Advanced Light Source and Advanced Photon Source.

非技术摘要：尽管半导体纳米晶体 (NC) 在光伏、固态照明和纳米电子学领域的应用显示出巨大的前景，但组装设备的成功将主要取决于 NC 组件的导电性能。用于表征这些系统的传统实验探针通常不探索对原子种类敏感或在原位进行的技术。因此，必须确定新的实验探针，以提供其他方法无法获得的有关 NC 的关键信息。该项目由 NSF 固态和材料化学项目支持，采用最先进的 X 射线表征方法来阐明 NC 文献中各种未解答的问题，包括 NC 中的阳离子交换机制和配体化学对NC中载流子动力学的影响。该项目重点关注原位软和硬 X 射线吸收光谱以及超快 X 射线吸收光谱。这些技术在很大程度上还没有被用来探测半导体NC的化学和物理，预计它们将提供重要的见解来回答有关这些材料中的键合和电荷转移动力学的重要问题。反过来，这项研究计划的结果将对制造下一代纳米电子材料的能力产生重大影响。这项研究利用了表面科学与技术实验室 (LASST) 内庞大的基础设施，该实验室是一个跨学科中心，汇集了来自物理、化学、电气与计算机工程以及化学与生物工程的研究人员。该研究项目提供物理、化学和材料科学领域的高级研究生培训，特别是超高真空表面科学和材料表征，包括先进光源和先进光子源的同步加速器研究。此外，位于 LASST 的研究实验室通过参观进行展示，并将向许多贫困学生（包括大量美洲原住民）介绍最先进的仪器工具。技术摘要：该项目得到了 NSF 固态和材料化学项目的支持，对半导体纳米晶体 (NC) 中的电荷传输和阳离子交换等过程背后的基本机制进行了前所未有的研究。研究活动集中在原位软、硬 X 射线吸收光谱以及超快 X 射线吸收光谱。这些技术在很大程度上还没有被用来探测半导体NC的化学和物理，预计它们将提供重要的见解来回答有关这些材料中的键合和电荷转移动力学的重要问题。反过来，这项研究计划的结果将对制造下一代纳米电子材料的能力产生重大影响。这项工作的变革性特点是使用尖端的 X 射线技术在最常见的环境（解决方案阶段）中探测 NC。认识到控制 NC 中载流子密度和迁移率之间的相互作用将在制造高导电性 NC 器件中发挥重要作用，该项目的研究目标集中在两个相关的研究领域：(a) NC 的原位 X 射线光谱经历阳离子交换过程的材料以及 (b) 表面配体对 NC 中界面载流子动力学的影响（通过超快 X 射线光谱探测）。感兴趣的系统材料包括作为典型纳米材料的 CdSe。然而，所研究的一般机制将导致对新材料的研究，例如其他二元半导体（如 PbSe）或金属纳米结构（如 Ag 或 Pb）。该研究项目提供物理、化学和材料科学领域的高级研究生培训，特别是超高真空表面科学和材料表征，包括先进光源和先进光子源的同步加速器研究。