The Role of Local Heterogeneity in Organic Semiconductor Performance

技术：本提案的目标是研究局部纳米尺度的非均质性如何使用电扫描探针显微镜影响有机半导体的性能。通过引入新的实验能力来直接测量模型有机半导体薄膜电子特性的纳米级变化，并在微观水平上研究由加工参数变化引起的非均质性如何导致性能变化。本项目将解决独特的新挑战，包括：1)研究有机半导体中局部电流分布的演变作为加工引起的电荷输运紊乱的函数；2)利用局部扫描探针获取垂直膜结构的局部信息，构建光伏共混物的三维形貌图。3)利用时间分辨静电力显微镜研究亚100微秒和亚100 nm尺度上的捕获、解捕获和光化学降解动力学，探讨有机半导体薄膜中纳米尺度薄膜结构与捕获之间的相关性。这些目标对有机半导体领域具有根本性的科学重要性，并解决了这些系统中输运过程的基本描述：如果1D模型是不够的，那么3D模型包含必要的空间无序的最物理但最有效的方法是什么？理论上的失序参数如何与实验处理条件和观测值相联系？虽然有机物的形态/性能关系被广泛认为是影响从理论到合成到制造领域的核心挑战，但大多数表征形态的方法只允许将平均性能与平均局部结构相关联，从而忽略了局部异质性的重要作用。这一建议将有助于改变对有机半导体的理解和使用。非技术：该项目涉及与技术相关的材料科学专题领域的基础研究问题，并有望为跨学科领域的研究生和本科生培训提供独特的机会。预期这一研究项目还将通过培训这一研究领域的科学家，通过出版物广泛传播这一研究结果，产生更广泛的影响。拟议的研究计划将在化学、物理和材料科学的交叉点进行，并在光伏、节能显示器和照明领域具有技术应用。该提案将支持现有的教育项目，包括持续招募代表性不足的群体进入科学职业，向K- 12学生进行公共宣传，以及与当地社区进行更广泛的互动。该项目将创造新的本科研究项目、国际合作以及新的工业教育经验和伙伴关系。

Technical: The goal of this proposal is to study how local nanoscale heterogeneity affects the performance of organic semiconductors using electrical scanning-probe microscopy. By bringing novel experimental capabilities to directly measure nanoscale variations in the electronic properties of model organic semiconductor films and study at the microscopic level how heterogeneity arising from variations in processing parameters leads to variations in performance. This project will address unique new challenges including:1) Studying the evolution of local current distributions as a function of processing-induced disorder in charge transport in organic semiconductors;2) Obtaining local information about vertical film structure to construct a picture of 3D morphology in photovoltaic blends using local scanning probes.3) Using time-resolved electrostatic force microscopy to study trapping, de-trapping, and photochemical degradation kinetics on sub-100 microsecond, and sub-100 nm scales to probe correlations between nanoscale film structures and trapping in organic semiconductor films.These objectives are of fundamental scientific importance to the field of organic semiconductors and address basic description of transport processes in these systems: if 1D models are insufficient, what is the most physical yet efficient way for 3D models to include +the requisite spatial disorder? How are the disorder parameters in theory linked to experimental processing conditions and observables? While the morphology/performance relationship in organics is widely recognized as a central challenge that affects the field from theory to synthesis to manufacturing, most methods of characterizing morphology permit only a correlation of average performance with average local structure and thus overlook the important role of local heterogeneity. This proposal will help transform the understanding and use of organic semiconductors.Non-technical: The project addresses basic research issues in a topical area of materials science with technological relevance, and is expected to provide unique opportunities for graduate and undergraduate training in an interdisciplinary field. This research project is also expected to have broader impacts through the training of scientists in this research field, through the wide dissemination of the findings of this research through publications. The proposed research program will take place at the intersection of chemistry, physics, and materials science, and has technological applications in the areas of photovoltaics, energy efficient displays, and lighting. This proposal will support established educational programs including ongoing recruitment of under-represented groups into scientific careers, public outreach to K- 12 students, and broader interactions with the local community. The project will create new undergraduate research projects, international collaborations, and new industrial educational experiences and partnerships.