"Bottom-Up" Design of Nanostructured Conducting Polymer Thin Films

技术概述：有效控制有机半导体聚合物薄膜的纳米级形貌是设计更高效的薄膜器件（包括有机发光器件和光伏器件）的重要前提。目前这种器件的“自上而下”范例是基于利用可溶性半导体聚合物的溶液处理。这种方法通常只提供对纳米级分子组织和相分离的适度控制。使用预合成共轭聚合物溶液的潜在替代方案是“自下而上”的方法，通过小分子单体的表面引发聚合来制备共轭聚合物的表面接枝薄膜。该项目的最终目标是开发一种模块化的，自下而上的策略，以具有层次控制分子组织的表面固定化纳米结构半导体聚合物薄膜材料。该策略包括纳米球光刻图像化与表面原位聚合的结合，通过简单而有效的化学反应。本项目的具体目标是：(1)研究纳米球光刻技术制备半导体聚合物前体纳米化固定化单层膜的方法；(2)开发利用化学（如金属催化活性聚合和/或“点击”化学）或电化学方法将前驱体单层转化为半导体聚合物表面固定的纳米结构薄膜的方法；(3)应用(1)和(2)的结果，设计一种自下而上的模块化策略来制备块状异质结薄膜太阳能电池。这些目标的实现是通过对表面引发聚合的机制和条件进行广泛的基础研究来实现的，这些研究旨在改善共轭聚合物的分子参数和薄膜中的大块分子组织。这些研究结果可能通过有效和精确地控制聚合物薄膜中的分子结构和纳米级组织，为有机电子用聚合物薄膜材料的设计创造新的范例。非技术总结：尽管有机半导体聚合物领域最近取得了进展，但它离提供一个真正经济可行的无机材料替代品还很远。这个跨学科项目将通过开发新的有潜力的方法来制备光伏应用的薄膜有机聚合物材料，直接影响国家能源安全。这可能会导致高效可靠的有机聚合物太阳能电池。虽然这应该被视为该项目的主要实际成果，但它也旨在促进表面引发聚合的发展和基本理解，以及复杂有机材料中纳米级组织的过程。学生将接受有机合成、器件制造技术、材料和器件特性方面的培训，并将学习现代理论和计算方法。他们将获得并发展强大的多学科技能和专门知识，以便在当前的高科技就业市场上具有竞争力。除此之外，参与该项目的学生将参与各种正在进行的更广泛的活动，目的是提高公众对现代科学技术及其对人们生活的影响的认识和欣赏，并培养对科学的兴趣，特别是年轻一代。这将通过各种社区外展项目来实现，例如在公立学校进行讲座和示范，特别强调表现不佳的学校。

TECHNICAL SUMMARY:Effective control of nanoscale morphology of organic semiconducting polymer thin films is an important prerequisite for designing more efficient thin-film devices including organic light-emitting and photovoltaic devices. The current "top-down" paradigm to such devices is based on utilizing solution-based processing of soluble semiconducting polymers. This approach generally provides only modest control over nanoscale molecular organization and phase separations. A potentially transformative alternative to using solutions of pre-synthesized conjugated polymers would be a "bottom-up" approach to prepare surface-grafted thin films of conjugated polymers by surface-initiated polymerization of small-molecule monomers. The ultimate goal of this project is to develop a modular, bottom-up strategy to surface-immobilized nanostructured semiconducting polymer thin-film materials with hierarchically controlled molecular organization. This strategy includes a combination of nanosphere lithographic patterning with surface-initiated in situ polymerization through simple and efficient chemistries. The project focuses on the following specific aims: (1) studies on nanosphere lithography as a method to prepare nanopatterned immobilized monolayers of semiconducting polymer precursors; (2) development of methods to convert the precursor monolayers into surface-immobilized nanostructured films of semiconducting polymers by using chemical (such as metal-catalyzed living polymerization and/or "click" chemistry) or electrochemical approaches; (3) applying the outcomes of (1) and (2) to design a bottom-up modular strategy to preparation of bulk heterojunction thin-film solar cells. Realization of these goals is being done through broad-range fundamental studies on mechanisms and conditions of the surface-initiated polymerization aimed at improving both the molecular parameters of the conjugated polymers and bulk molecular organization in the thin films. The outcome of these studies may create a new paradigm for design of polymer thin-film materials for organic electronics through the efficient and precise control over molecular structure and nanoscale organization in the polymer films.NON-TECHNICAL SUMMARY:Despite the recent advances in the field of organic semiconducting polymers, it is still far from offering a real economically viable alternative to inorganic materials. This interdisciplinary project will directly impact the national energy security by developing new potentially promising approaches to preparing thin-film organic polymer materials for photovoltaic applications. This can potentially lead to efficient and reliable organic polymer solar cells. While this should be seen as a major practical outcome of this project, it is also aimed to contribute to development and fundamental understanding of surface-initiated polymerization, as well as processes of nanoscale organization in complex organic materials. The students will be trained in organic synthesis, device fabrication techniques, materials and device characterization, and will learn modern theoretical and computational methods. They will acquire and develop strong multidisciplinary skills and expertise required to be competitive in the current high-tech job market. Beyond that, students working on this project will be involved in a variety of ongoing broader activities with the goal to improve public awareness and appreciation of modern science and technology and its impact on people's lives, and create interest in science, especially to younger generations. This will be done through various community outreach programs such as lectures and demonstrations in public schools, with a particular emphasis on underperforming schools.