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

该项目是基于三个研究小组之间的合作，一个在材料科学和分析（SAM）部门在G。在卢森堡的李普曼研究中心和密歇根大学（UM）材料科学系的两个。 这种伙伴关系合并了每个参与者无法单独使用的资源。 本研究的目的是调查的形状，成分的定义，并在气相沉积的多层有机半导体薄膜和设备制造的UM组之一的接口的能量。 光电器件的日益复杂化要求在具有专门设计的界面的多层结构的制造中进行分子水平的尺寸控制。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通常仍未得到验证。这对于基于共轭有机化合物的器件尤其如此，其在能源应用中的用途越来越多（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，掩埋的界面是简单地不可接近的或遭受损坏。 低能量二次离子质谱（LE-SIMS），SAM组的一个专业，提供了一个有前途的途径，用于分析有机基薄膜层状结构，因为sub-keV的初级离子的冲击能量的结果在样品表面的分子种类的碎片减少。 碰撞级联的物理学和导致低能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。 追求这一知识，其他UM组结合大规模分子动力学（MD）模拟与第一性原理密度泛函理论（DFT）计算，研究碰撞级联中的详细原子轨迹，并预测喷射分子碎片的性质。 该计算框架用于解释LE-SIMS获得的实验数据，从而提高该技术的深度分辨率和可靠识别有机分子种类的能力，从而进一步确立LE-SIMS作为深度剖析有机薄膜材料的技术。和性质的多层薄膜有机半导体以前所未有的精度。 有机电子器件设计和制造技术的进步的基本见解。 该项目作为三个博士学位的基础。论文 学生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，从多样化的教育体验中受益。 本科生直接参与学术层面，K-12学生通过UM的新外展活动。

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.