Understanding the Roles of Intra- and Interchain Order on Spin-Dependent Electronic Processes in Self-Assembled Conjugated Polymer Aggregates

了解链内和链间有序对自组装共轭聚合物聚集体中自旋相关电子过程的作用

• 批准号: 1506558
• 负责人: John Grey
• 金额: $ 43.5万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2019-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1506558&HistoricalAwards=false
• 关键词: Understanding; Roles; Intra; Interchain; Order

With this award, the Macromolecular, Supramolecular and Nanochemistry Program of the Chemistry Division is supporting Professor John Grey of the University of New Mexico to study spin-dependent processes in self-assembled polymeric systems. Conjugated polymers are large chains consisting of a basic molecular repeat unit that absorb light and conduct charges making them excellent candidates for next-generation optoelectronic applications. For example, these so-called 'plastic' semi-conductors are used in solar cells and light emitting displays, which may eventually replace existing technologies owing to their ever increasing efficiencies over the last 10 years and relatively low cost. The ways in which the polymer chains fold and pack in thin films has a significant impact on the overall performance of organic solar cells and light-emitting devices (OLEDs). The proposed research will use new strategies to fabricate ordered polymer structures and study how electrical charges are formed and how electrical current can be generated more efficiently in the resulting films. In addition, the PI and his NSF-sponsored graduate students actively participate in ongoing educational and research infrastructure development programs at the University of New Mexico. These activities include coordinating with the local Center for Integrated Nanotechnologies (CINT) to increase the participation of undergraduate and graduate researchers through collaboration with CINT staff scientists. Students take part by writing user proposals that undergo peer review thus providing valuable experience in designing and executing an independent research project. Lastly, student participants gain valuable and diverse skill sets in academic fields essential for national interests. The interactions between and inter-conversion of electrically neutral (exciton) and charged (polaron) states of different spin in conjugated polymer materials has significant bearing on their overall performance in cutting-edge optoelectronic devices, such as solar cells. Although the outcomes of these processes are strongly dependent on polymer structure, detailed molecular level structure-function relationships have proven difficult to obtain from conventional polymer functional forms (i.e., bulk thin films). This difficulty originates from morphological heterogeneity due to intrinsic molecular weight poly-dispersity of polymers. The proposed research seeks to overcome heterogeneity effects to understand how molecular structure regulates interactions and inter-conversion of excitonic and polaronic spin states. Self-assembly approaches are used to fabricate well-defined polymer aggregate supramolecular nanostructures that can be exploited to selectively control conformational and packing (intra- and interchain) order and electronic coupling. The Grey group at the University of New Mexico has pioneered this approach to direct exciton coupling and polaron interactions in polymer aggregates that are leveraged in the proposed research to address longstanding fundamental questions involving spin state exchange interactions and crossover in polymeric semiconductors. This research also takes new directions for interrogating the fates and interactions of different spin states in individual polymer nanostructures by introducing sensitive and selective electric- and magnetic-field dependent molecular spectroscopic and imaging techniques. The research aims to establish design rules for reliably tuning subtle polymer chain packing and order within supramolecular assemblies to understand and control exchange interactions and spin state inter-conversion for improved material performance.

有了这个奖项，化学部的大分子，超分子和纳米化学计划支持新墨西哥大学的约翰·格雷教授，研究自组装聚合系统的自旋依赖性过程。共轭聚合物是由基本的分子重复单元组成的大链，该单元吸收光线并进行电荷，使其成为下一代光电应用的出色候选者。例如，这些所谓的“塑料”半导体用于太阳能电池和发光显示器，由于过去10年中其效率不断提高，并且成本相对较低，因此最终可能会取代现有技术。 聚合物链在薄膜中折叠和包装的方式对有机太阳能电池和发光设备（OLED）的整体性能产生了重大影响。 拟议的研究将使用新的策略来制造有序的聚合物结构，并研究如何形成电荷以及如何在产生的膜中更有效地产生电流。 此外，PI和他的NSF赞助的研究生积极参加了新墨西哥大学正在进行的教育和研究基础设施发展计划。这些活动包括与当地综合纳米技术中心（CINT）协调，以通过与CINT员工科学家的合作来增加本科和研究生研究人员的参与。 学生通过编写接受同行评审的用户建议来参加，从而在设计和执行独立研究项目方面提供了宝贵的经验。 最后，学生参与者在国家利益至关重要的学术领域中获得了宝贵而多样的技能。在共轭聚合物材料中，电气中性（激子）和带电（二极管）状态的电动（激子）状态之间的相互作用和转换之间的相互作用与尖端光电设备（例如太阳能电池）中的总体性能显着取决于它们的总体性能。 尽管这些过程的结果很大程度上取决于聚合物的结构，但事实证明，详细的分子水平结构 - 功能 - 函数 - 功能 - 从常规聚合物功能形式（即散装薄膜）很难获得。 这一困难源于由于聚合物的固有分子量多分散性而导致的形态异质性。 拟议的研究旨在克服异质性效应，以了解分子结构如何调节激子和二极管旋转状态的相互作用和转换。 自组装方法用于制造明确定义的聚合物骨料超分子纳米结构，这些纳米结构可用于选择性地控制构象和填料（内和链）和电子耦合。 新墨西哥大学的灰色群体率先提出了这种方法来指导激子耦合和在拟议的研究中利用的聚合物聚集体中的极化耦合，以解决涉及旋转状态交换的长期基本问题，这些问题涉及旋转状态交换和聚合物半导体中的交叉。 这项研究还采用了新的方向来询问单个聚合物纳米结构中不同自旋状态的命运和相互作用，通过引入敏感和选择性的电场和磁场依赖性分子光谱和成像技术。 该研究旨在建立设计规则，以可靠地调整超分子组件内的微妙聚合物链填料和订单，以了解和控制交换交互作用，并控制旋转状态相互转换以提高材料性能。