Unipolar n-Type Semiconducting Polymers: Synthesis, Electron Transport, and Use in All-Polymer Solar Cells

非技术总结：社会对新型材料和设备的需求很大，这些材料和设备可能使太阳能转换技术在成本上具有化石燃料的竞争力。与目前广泛研究的聚合物/富勒烯太阳能电池相比，该项目中研究的由聚合物材料制成的太阳能电池具有更强的热、化学和光化学坚固性，更便宜，更容易大规模生产的潜力。PI和他的团队将创建这些材料的构建模块，研究它们的结构和性能，并制造由这些新材料制成的太阳能电池，以研究它们的电子特性和性能。除了该项目潜在的技术影响外，其他更广泛的影响将包括：(1)在能源技术材料领域教育研究生和本科生；(2)将本项目的成果整合到研究生和本科生的课程中，开发和改进课程；(3)通过期刊发表、会议报告等方式传播项目成果，并通过组织专题讨论会促进各学科间关于太阳能的思想交流；(4)与西雅图太平洋科学中心（PSC）合作，为公众提供有关太阳能和塑料材料的互动展览。PI将继续并扩大他长期以来在研究项目中对女性和少数民族学生的参与。技术概述：该项目的总体目标是合成和研究具有高电子迁移率、高能级、高结晶度和高分子量的新型单极n型半导体聚合物，适合用作高效全聚合物体异质结太阳能电池的电子受体组件。计划中的研究有三个相互关联的科学目标：(i)基于萘二亚胺（NDI）构建块和最近发现的苯并氟蒽二亚胺（BFI）构建块设计、合成和开发新的单极电子接受（n型）共轭聚合物半导体；（ii）利用有机场效应晶体管和空间电荷限制电流（SCLC）技术研究新型受体半导体聚合物的体和场效应电子输运特性；（iii）制造包含新受体聚合物的全聚合物BHJ太阳能电池，并研究其纳米级形貌，光伏和电荷传输特性，以及潜在的结构-性能-器件性能关系。需要探讨的问题包括：是否可以开发出可溶的n型聚合物半导体，在光伏性能上与被广泛研究的富勒烯相媲美或超越？与聚合物/富勒烯系统相比，全聚合物太阳能电池的器件效率损失机制有多相似或不同？揭开这些问题的答案将产生新的基本物理见解，为低成本有机光伏发电的发展奠定基础。研究生将参与拟议研究的各个方面，使PI的教育和研究计划得以整合。

NON-TECHNICAL SUMMARY:There is a major societal need for novel materials and devices that could potentially render solar energy conversion technologies cost-competitive with fossil fuels. Solar cells made of the polymeric materials to be investigated in this project offer the potential to be more thermally, chemically and photochemically rugged, cheaper, and more readily manufacturable on a large scale compared to the currently more widely studied polymer/fullerene counterparts. The PI and his group will create the building blocks for these materials, study their structures and properties, and fabricate solar cells made of these new materials for investigation of their electronic properties and performance. In addition to the potential technological impacts of this project, other broader impacts will include: (1) educating graduate and undergraduate students in the field of materials for energy technologies; (2) developing and improving curricula by integrating the results of this project into courses for graduate and undergraduate students; (3) disseminating the project results through journal publications, conference presentations, and fostering cross-fertilization of ideas on solar energy among various disciplines through organization of symposia; and (4) partnering with the Pacific Science Center (PSC) of Seattle to bring interactive exhibits on solar energy and plastic materials to the general public. The PI will continue and expand his long-standing involvement of women and minority students in his research program.TECHNICAL SUMMARY:The overall goal of this project is to synthesize and investigate new unipolar n-type semiconducting polymers with high electron mobility, a range of energy levels, high crystallinity, and high molecular weights suitable for use as the electron acceptor component in highly efficient all-polymer bulk heterojunction solar cells. The planned research has three interrelated scientific objectives: (i) design, synthesize, and develop new unipolar electron-accepting (n-type) conjugated polymer semiconductors based on naphthalene diimide (NDI) building blocks and recently discovered benzofluoroanthene diimide (BFI) building blocks; (ii) investigate the bulk and field-effect electron transport properties of the new acceptor semiconducting polymers by means of organic field-effect transistor and space charge limited current (SCLC) techniques; and (iii) fabricate all-polymer BHJ solar cells incorporating the new acceptor polymers and investigate their nanoscale morphology, photovoltaic and charge transport properties, and underlying structure-property-device performance relationships. Among the questions to be explored are: Can soluble n-type polymer semiconductors be developed that rival or surpass the widely studied fullerenes in photovoltaic performance? How similar or different are the device efficiency loss mechanisms in all-polymer solar cells versus polymer/fullerene systems? Uncovering the answers to these questions will produce basic new physical insights to underpin the advancement of low-cost organic photovoltaics. Graduate students will be engaged in all facets of the proposed research, enabling the integration of the educational and research programs of the PI.