Materials World Network: Growth, Kinetics, and Morphology of Multi-Layered Organic Thin Films via Low-Energy Secondary Ion Mass Spectrometry

材料世界网络：通过低能二次离子质谱法研究多层有机薄膜的生长、动力学和形态

• 批准号: 0806867
• 负责人: John Kieffer
• 金额: $ 60万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-15 至 2012-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0806867&HistoricalAwards=false
• 关键词: Materials; World; Network; Growth; Kinetics

This project is based on a partnership between three research groups, one at the Science and Analysis of Materials (SAM) Department at the G. Lippmann Research Center in Luxembourg and two at the Materials Science Department of the University of Michigan (UM). This partnership merges resources that are not available to each participant individually. The purpose of this research is to investigate the shape, compositional definition, and energetics of interfaces in vapor-deposited multi-layer organic semiconductor thin films and devices fabricated by one of the UM groups. The increasing sophistication of optoelectronic devices requires molecular-level dimensional control in the fabrication of multi-layered structures with specifically engineered interfaces. However, the effectiveness of growth and doping strategies devised to achieve the desired device structures oftentimes remains unverified due to the lack adequate characterization techniques. This is particularly true for devices based on conjugated organic compounds, which find increasing use in energy applications (e.g. organic light-emitting diodes and organic photovoltaic cells, etc.). The buried interfaces are simply inaccessible or suffer damage when using conventional characterization techniques. Low-energy secondary ion mass spectrometry (LE-SIMS), a specialty of the SAM group, provides a promising avenue for the analysis of organic-based thin-film layered structures, because sub-keV impact energies of the primary ions result in reduced fragmentation of molecular species at the specimen surface. The physics of the collision cascades and the processes that lead to the ejection of secondary ions at low energies is still poorly understood, and a unified formalism for the identification of ejected species does not yet exist. Pursuing this knowledge, the other UM group combines large-scale molecular dynamics (MD) simulations with first-principles density functional theory (DFT) calculations to study the detailed atomic trajectories in collision cascades and predict the nature of ejected molecular fragments. This computational framework serves to interpret experimental data obtained from LE-SIMS, thereby improving the depth resolution of the technique and its ability to reliably identify organic molecular species, thus further establishing LE-SIMS as a technique for depth-profiling organic thin film materials.The goal of this project is to establish the relationship between growth conditions, structure, and properties of multi-layer thin film organic semiconductors with unprecedented precision. Fundamental insights for the advancement of organic electronic device design and fabrication techniques are anticipated. The project serves as the basis for three Ph.D. theses. Students benefit from a diverse educational experience through exchange visits to partner institutions, remote interactions between researchers, sharing of data, and the use of cyber infrastructure for the dissemination of findings through. Undergraduate students are involved directly at an academic level, and K-12 students through new outreach initiatives at UM.

该项目基于三个研究小组之间的合作，其中一个研究小组位于卢森堡 G. Lippmann 研究中心的材料科学与分析 (SAM) 系，两个研究小组位于密歇根大学 (UM) 材料科学系。 这种伙伴关系合并了每个参与者无法单独使用的资源。 本研究的目的是研究由 UM 团队之一制造的气相沉积多层有机半导体薄膜和器件中界面的形状、成分定义和能量学。 光电器件日益复杂，需要在具有专门设计的界面的多层结构的制造中进行分子级尺寸控制。然而，由于缺乏足够的表征技术，为实现所需器件结构而设计的生长和掺杂策略的有效性常常仍未得到验证。对于基于共轭有机化合物的器件尤其如此，这些器件在能源应用中的使用越来越多（例如有机发光二极管和有机光伏电池等）。当使用传统的表征技术时，埋入的界面根本无法接近或遭受损坏。 低能二次离子质谱 (LE-SIMS) 是 SAM 小组的专业技术，为分析有机薄膜层状结构提供了一种有前途的途径，因为一次离子的亚 keV 冲击能量可减少样品表面分子物质的碎片。 碰撞级联的物理原理以及导致低能量二次离子喷射的过程仍然知之甚少，并且还不存在用于识别喷射物质的统一形式。 为了追求这些知识，密歇根大学的另一个小组将大规模分子动力学（MD）模拟与第一原理密度泛函理论（DFT）计算相结合，以研究碰撞级联中详细的原子轨迹并预测喷射分子碎片的性质。 该计算框架用于解释从 LE-SIMS 获得的实验数据，从而提高该技术的深度分辨率及其可靠识别有机分子种类的能力，从而进一步确立 LE-SIMS 作为有机薄膜材料深度分析技术的地位。该项目的目标是以前所未有的精度建立多层薄膜有机半导体的生长条件、结构和性能之间的关系。 预计有机电子器件设计和制造技术进步的基本见解。 该项目是三名博士学位的基础。论文。 通过对合作机构的互访、研究人员之间的远程互动、数据共享以及使用网络基础设施传播研究结果，学生受益于多样化的教育体验。 本科生直接参与学术活动，K-12 学生则通过密西根大学新的外展活动参与。