Confined Self Assembly of Semiconducting Polymers in Nanofibers

世界上90%的能源来自不可再生的碳资源，每年导致320亿吨二氧化碳排放。该项目的目标是研究塑料(或有机)太阳能电池中使用的新型聚合物材料的形态，这种材料可以将清洁和丰富的太阳能转化为可用电能。与传统的硅基太阳能电池相比，有机太阳能电池的成本较低，因此特别有吸引力。然而，它们的低效率一直是其广泛部署的关键障碍。塑料太阳能电池的不同半导体功能部件之间的材料结构的精确控制是太阳能高效转化为电能的关键。这项工作中的新型聚合物将以纳米纤维的形式进行加工，这不仅将使我们能够在纳米尺度上更好地控制和定制这些结构，以提高设备效率，而且还将使具有集成太阳能电池的轻便和透气的智能织物成为可能。该项目将为一名研究生和几名本科生提供纳米材料和可再生能源的跨学科教育经验。该项目的具体目标是将实验和模拟相结合，研究共轭棒-棒嵌段共聚物在电纺纳米纤维(直径=50-500纳米)中的自组装。由于静电纺丝过程中溶剂挥发快，停留时间短(在毫秒量级)，初始溶液中的微观结构很可能对所制得的纳米纤维的最终组装产生重大影响。因此，我们将研究纳米纤维制备的三个阶段(溶液阶段、干燥/溶剂挥发和制备后热处理)在确定最终的分级自组装结构中的作用。将进行多尺度模拟，以了解指导受限系统中自组装的热力学和动力学原理。在该项目的最后阶段，将在塑料太阳能电池中进行材料的光学特性和性能表征。这项工作将是首次研究共轭嵌段共聚物在纳米纤维中的自组装，具有开发可穿戴智能织物的潜力。

Ninety percent of the world's energy is derived from non-renewable carbon resources, resulting in 32 billion metric tons of carbon dioxide emissions every year. The objective of this project is to investigate the morphology within novel polymeric materials for use in plastic (or organic) solar cells that convert clean and abundant solar energy to usable electricity. Organic solar cells are particularly attractive due to their low cost compared to the conventional silicon-based solar cell devices. However, their low efficiency has been a key impediment in their broad deployment. Precise control over material structure between the different semiconducting functional components of plastic solar cells is critical for efficient conversion of solar energy to electricity. The novel polymers in this work will be processed in the form of nanofibers, which will not only allow us to better control and tailor these structures at the nanometer length scale for enhanced device efficiency, but will also enable light and breathable smart fabrics with integrated solar cells. This project will provide one graduate and several undergraduate students with an interdisciplinary educational experience in nanomaterials and renewable energy.The specific objective of this project is to combine experiments and simulations to investigate self-assembly of conjugated rod-rod block copolymers within electrospun nanofibers (diameter = 50-500 nanometers). Owing to the rapid solvent evaporation and short residence time during electrospinning (on the order of milliseconds), the microstructure in the initial solution is likely to have a significant influence on the final assembly in as-made nanofibers. Therefore, the role of each of the three stages of nanofiber fabrication (solution phase, drying/solvent evaporation and the post fabrication annealing) in defining the final hierarchical self-assembly structures will be investigated. Multi-scale simulations will be conducted to understand the thermodynamic and kinetic principles that direct self-assembly in confined systems. Optical property and performance characterizations of the materials will be conducted in plastic solar cells in the final stage of the project. This work will serve as the first ever study on self-assembly of conjugated block copolymers in nanofibers, with the potential to develop wearable smart fabrics.