Structure and Properties of Defects in Organic Molecular Semiconductors

技术概述：人们对聚合物和有机分子材料用于各种光电有源器件的构建有着浓厚的兴趣。尽管这些材料具有重要意义，但有机分子膜的形态与其宏观性质之间的关系仍然不完全清楚。有机分子晶体中结构缺陷的性质及其对宏观性能的影响还有待进一步研究。由于这些固体的扩展分子连通性，其晶界（2-D）、位错（1-D）和空位（0-D）缺陷的能量学、结构和迁移性可能与无机晶体中的缺陷大不相同。我们一直专注于光电活性有机分子和聚合物材料中特定缺陷结构和性能的基础研究。最近，我们研究了tips -并五苯的加工和结构，tip -并五苯是一种可溶的变体，与苊环面对面包装。我们开发了低剂量高分辨率电子显微镜（HREM）成像技术，用于直接观察晶体、液晶聚合物和有机分子膜中的缺陷微结构。我们现在建议进一步研究具有功能的并五苯变体的结构和性质，以更好地控制其固态包装和宏观性质。我们将集中研究一系列的并五苯衍生物，旨在提高在有机溶剂中的溶解度，稳定液晶中间相的形成，并促进固态中并五苯环之间的面对面堆积。这些新材料的结构表征将利用密歇根大学现有的各种仪器，包括光学显微镜、宽角和小角x射线散射、扫描电子显微镜、扫描探针显微镜和透射电子显微镜。这一建议的智力优点是它的重点特征形态和缺陷结构的一系列新的高结晶，功能化的并五苯衍生物感兴趣的有机电子器件。我们将确定这些新材料的微观结构和宏观性能之间的关系。我们期望我们的结果将继续对优化现有材料的加工条件和激励未来的分子设计有用。非技术概述：有机分子和聚合物材料的发展对“塑料电子”应用有相当大的兴趣，如射频识别标签、柔性显示器和生物传感器。该项目将使用密歇根大学提供的先进显微技术研究这些材料的详细微观结构。获得的信息将使设计具有增强性能的新材料成为可能。该项目将包括为材料科学与工程专业的研究生提供全日制支持，还将通过大学研究机会计划（UROP）、玛丽安·萨拉·帕克（Marian Sarah Parker）女工程学生计划、少数民族工程计划办公室（MEPO）、美国宇航局/夏普（NASA/Sharp）高中生暑期计划以及与安娜堡格林希尔高中（greenhillhigh school）合作的暑期研究计划，为本科生提供研究经验。

TECHNICAL SUMMARY:There is intense continuing interest in the use of polymer and organic molecular materials for the construction of a variety of optoelectronically-active devices. Despite the importance of these materials, the relationship between the morphology of the organic molecular film and its macroscopic properties remains incompletely understood. The nature of the structural defects in organic molecular crystals and their influence on macroscopic properties still needs to be determined in detail. Because of the extended molecular connectivity of these solids, the energetics, structure, and mobility of the grain boundary (2-D), dislocation (1-D), and vacancy (0-D) defects can be quite different than those seen in inorganic crystals. We have been focusing on fundamental studies of specific defect structures and properties in organic molecular and polymer materials that are optoelectronically active. Most recently, we have investigated the processing and structure of TIPS-pentacene, a soluble variant that packs with the acene rings face-to-face. We have developed Low Dose High Resolution Electron Microscopy (HREM) imaging techniques for the direct observation of defect microstructures in crystalline and liquid crystalline polymers and organic molecular films. We now propose additional studies on the structure and properties of pentacene variants with functionalities designed to better control their solid-state packing and macroscopic properties. We will concentrate our efforts on a series of pentacene derivatives designed to enhance solubility in organic solvents, stabilize the formation of liquid crystalline mesophases, and promote face-to-face packing between the acene rings in the solid-state. The structural characterization of these new materials will take advantage of a variety of instrumentation available at the University of Michigan including Optical Microscopy, Wide and Small Angle X-ray Scattering, Scanning Electron Microscopy, Scanned Probe Microscopy, and Transmission Electron Microscopy. The intellectual merit of this proposal is its focus on the characteristic morphologies and defect structures of a new series of highly crystalline, functionalized pentacene derivatives of interest for organic electronic devices. We will determine relationships between the microstructure and the macroscopic properties of these new materials. We expect that our results will continue to be useful for optimizing processing conditions of existing materials and for motivating future molecular designs. NON-TECHNICAL SUMMARY: There is considerable interest in the development of organic molecular and polymer materials for "plastic electronic" applications such as radio-frequency identification tags, flexible displays, and biosensors. This project will investigate the detailed microstructure of these materials using advanced microscopic techniques available at the University of Michigan. The information obtained will make it possible to design new materials with enhanced performance. The project will involve full-time support for a graduate student in Materials Science and Engineering, and will also provide research experience for undergraduates through the University Research Opportunity Program (UROP), the Marian Sarah Parker program for female engineering students, the Minority Engineering Program Office (MEPO), the NASA/Sharp summer program for high school students, and an outreach summer research program with Greenhills High School in Ann Arbor.