Transmission electron microscopy of conjugated polymers using energy-filtering and phase contrast enhancement

使用能量过滤和相衬增强的共轭聚合物的透射电子显微镜

• 批准号: 1609417
• 负责人: Enrique Gomez
• 金额: $ 41万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2019-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1609417&HistoricalAwards=false
• 关键词: Transmission; electron; microscopy; conjugated; polymers

PART 1: NON-TECHNICAL SUMMARYThe properties of various polymeric materials depend on the structure at the nanoscale. As a consequence, characterizing the arrangement and order of polymers at nanometer length scales is crucial for the continued development of new materials. Much progress in this area is due to the application of advanced microscopy techniques (transmission electron microscopy) to complex polymeric systems in order to resolve the structure at very high resolutions. New developments in electron microscopy instrumentation are pushing the limits of what is possible, but these advances have not been tailored for the microscopy of polymers, which are very sensitive to electron beams and undergo rapid damage. This project will develop electron microscopy tools to image the structure of electrically conducting polymers used in a variety of emerging electronic applications, such as transistors and solar cell devices. By demonstrating new approaches for resolving the morphology with sub-nanometer resolution, this research will advance the fundamental science of how the chemical composition of polymers leads to the microstructure and aid in the development of polymers for flexible electronics applications. Furthermore, integrated educational and research activities will also include recruitment and retention of students from underrepresented groups. The investigators involved in this project will further support diversity in engineering education by offering mentorship and research experiences to undergraduate students. PART 2: TECHNICAL SUMMARYThis project will develop advanced electron microscopy tools for the study of polymeric materials. New methods to generate contrast in the electron microscope are warranted because of the complexity of the microstructure of conjugated polymer systems. The proposed work begins by examining radiation damage in the transmission electron microscope using two observables: diffraction intensities and low-loss electron energy-loss spectroscopy. These measurements will guide further experiments and establish limits of imaging modalities. Low-loss energy-filtered transmission electron microscopy will generate high-resolution images of long-range order in conjugated polymers. Phase plates will enhance contrast in both bright-field and focused-probe modes to enable imaging of polymer/fullerene mixtures, polymer blends, and block copolymers used in photovoltaics. Furthermore, charge transport heterogeneity will be examined using low-loss spectrum imaging to see deviations in density of states under bias, and by imaging local variations in electric fields that result from charge heterogeneity using a phase plate. Overall, this proposal will demonstrate the utility of monochromated electron sources and phase plates for imaging of conjugated polymers. Educational objectives are motivated by the need to enhance diversity in engineering. A number of specific programs will be implemented encompassing recruitment, retention, and mentoring of underrepresented groups.

第1部分：非技术总结各种聚合物材料的特性取决于纳米级的结构。 结果，表征在纳米长度尺度下聚合物的排列和顺序对于持续开发新材料至关重要。 该领域的许多进展是由于将高级显微镜技术（透射电子显微镜）应用于复杂的聚合系统，以便在非常高分辨率下解决结构。 电子显微镜仪器的新发展正在推动可能的限制，但是这些进步尚未针对聚合物的显微镜量身定制，这些聚合物对电子束非常敏感并受到快速损害。 该项目将开发电子显微镜工具，以成像用于各种新兴电子应用（例如晶体管和太阳能电池设备）的电导导电聚合物的结构。 通过展示通过亚纳米分辨率解决形态的新方法，这项研究将推进基础科学，即聚合物的化学组成如何导致微观结构并有助于开发用于柔性电气应用的聚合物。 此外，综合教育和研究活动还将包括招募和保留人数不足的群体的学生。 参与该项目的调查人员将通过向本科生提供指导和研究经验来进一步支持工程教育的多样性。 第2部分：技术摘要项目将开发用于研究聚合物材料的高级电子显微镜工具。 由于共轭聚合物系统的显微结构的复杂性，因此需要在电子显微镜中产生对比度的新方法。 提出的工作首先使用两个可观察到的透射电子显微镜中的辐射损伤：衍射强度和低损失电子损失光谱。 这些测量将指导进一步的实验并建立成像方式的限制。 低损坏的滤波器透射电子显微镜将在共轭聚合物中生成长距离顺序的高分辨率图像。 相板将增强在光场和聚焦模式中的对比度，以实现聚合物/富勒烯混合物，聚合物混合物以及用于光伏的共聚物的成像。 此外，将使用低损耗光谱成像检查电荷转运异质性，以查看偏置状态下状态密度的偏差，并通过对使用相板的电荷异质性产生的电场中的局部变化进行成像。 总体而言，该提案将证明单色电子源和相板的实用性，用于成像共轭聚合物。 教育目标是出于提高工程多样性的必要性而激发的。 将实施许多特定计划，包括招聘，保留和指导代表性不足的群体。