SGER: Spin-Polarized Electronic Processes in Conjugated Polymer Optoelectronic Devices

有机共轭聚合物是一类新型的半导体材料，具有材料可加工性好、性能可调等特点，在大面积柔性薄膜光电子器件中具有重要的应用前景。与无机半导体相比，聚合物具有一个重要的显著特征：不同自旋组态的单态和三态共存。因此，由于外部自旋极化电荷转移或自旋注入引起的净自旋极化将对与单态和三重态相关的电子过程产生重大影响，并可能为控制基于磁相互作用的有机共轭聚合物器件的光电性质开辟新的方向。目的：本项目旨在研究一个至关重要的问题：自旋极化电荷转移对有机半导体聚合物中单态和三态激子形成以及单-三重态系统交叉的影响。在为期一年的支持下，这一SGER将发展一个坚实的跨学科研究计划，全面研究自旋注入和转移对(I)光生极化激子(光伏)的激子解离，(Ii)自旋极化电荷捕获和释放(非易失性存储器)，(Iii)自旋极化电子-空穴复合(电致发光)，以及(Iv)有机n共轭材料中自旋相关激子-激子相干(激光作用)的影响。三)光电和磁性的高级表征。方法是首先了解自旋极化电荷从磁性纳米材料到共轭高聚物链的转移。其次，系统地研究了自旋转移对聚合物光电性能的影响。最后，我们将阐明磁相关激子的形成和系间交叉的机制。这些研究有望增加我们对磁性如何影响有机材料中的光电子过程的理解，从而导致有机器件的磁性增强功能和性能。广泛的影响：该项目将制定如何相互控制磁性和半导体性质的指导方针，因此将对开发用于大面积和灵活的光电子和自旋电子学应用的多功能半导体磁性有机材料做出重大贡献。这项研究包括交叉领域的调查，将为相关的研究生和本科生提供光学、电子学和磁学方面的多学科培训，让他们接触到与有机光电子和自旋电子材料和器件的发展有关的问题。为了进一步增强其教育影响力，该SGER将在田纳西大学开发聚合物物理(MSE 543)和聚合物材料和器件中的光电子工艺(MSE 674)的新课程。

Organic conjugated polymers are a new class of semiconducting materials and have demonstrated significant applications in large-area and flexible thin-film optoelectronic devices based on two unique features: convenient material processability and facile property-tuning. As compared with inorganic semiconductors, polymers have an important distinct feature: coexistence of differently spin-configured singlet and triplet states. As a result, a net spin-polarization due to external spin-polarized charge transfer or spin injection should have a significant impact on the electronic processes associated with the singlet and triplet states, and may open a new direction to control the optoelectronic properties of organic conjugated polymer devices based on magnetic interactions.Objective: This project seeks to investigate a critically important issue: effects of spinpolarized charge transfer on singlet and triplet exciton formation and singlet-triplet intersystem crossing in organic semiconducting polymers. With one-year support, this SGER will develop a solid interdisciplinary research program that will comprehensively study the effects of spin injection and transfer on (i) exciton dissociation of photogenerated polarized excitons (photovoltaics), (ii) spin-polarized charge trapping and releasing (nonvolatile memory), (iii) spin polarized electron-hole recombination (electroluminescence), and (iv) spin dependent exciton-exciton coherence (lasing actions) in organic n-conjugated materials.Intellectual merit: This project necessitates a truly interdisciplinary research effort, including: i) synthesis and processing of conjugated polymers and ferro-magnetic nanomaterials, ii) device fabrication, iii) advanced characterization of optoelectronic and magnetic properties. The approach is to first understand spin-polarized charge transfer from magnetic nano-materials to conjugated polymer chains. Secondly, the effects of spin transfer on polymer optoelectronic properties will be systematically investigated. Finally, mechanism of magnetic dependent exciton formation and intersystem crossing will be elucidated. The proposed studies are expected to increase our understanding on how magnetic properties affect the optoelectronic processes in organic materials, and thus will lead to magnetically enhanced functionalities and performance of organic devices.Broad impact: The project will develop a guideline of how to mutually control magnetic and semiconducting properties, and hence will significantly contribute to the development of multifunctional semiconducting magnetic organic materials for large-area and flexible optoelectronic and spintronic applications. The research consists of crossfield investigations that will provide multi-disciplinary training in optics, electronics, and magnetics to the involved graduate and undergraduate students by exposing them to problems related to the development of organic optoelectronic and spintronic materials and devices. To further enhance its educational impact, this SGER will develop new course work for Polymer Physics (MSE 543) and Optoelectronic Processes in Polymeric Materials and Devices (MSE 674) at the University of Tennessee.