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

有机共轭聚合物是一类新型半导体材料，由于其易于加工和易于调谐的特性，在大面积柔性薄膜光电器件中得到了广泛的应用。与无机半导体相比，聚合物具有重要的独特特征：不同自旋构型的单重态和三重态共存。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对与单线态和三重态相关的电子过程产生了重大影响，并可能为基于磁相互作用控制有机共轭聚合物器件的光电性能开辟了新的方向。目的：本项目旨在研究一个非常重要的问题：自旋极化电荷转移对有机半导体聚合物中单线态和三重态激子形成和单线态-三重态系统间交叉的影响。在为期一年的支持下，SGER将开发一个坚实的跨学科研究项目，全面研究自旋注入和转移对有机n共轭材料中(i)光产生极化激子的激子解离（光伏），（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）和（iv）自旋依赖激子-激子相干（激光作用）的影响。智力优势：该项目需要真正的跨学科研究努力，包括：i)共轭聚合物和铁磁纳米材料的合成和加工，ii)器件制造，iii)光电和磁性质的高级表征。该方法首先理解自旋极化电荷从磁性纳米材料转移到共轭聚合物链。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，阐述了磁依赖激子形成和系统间交叉的机理。所提出的研究有望增加我们对磁性如何影响有机材料中的光电过程的理解，从而将导致磁性增强有机器件的功能和性能。广泛影响：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，因此将为开发用于大面积和柔性光电和自旋电子应用的多功能半导体磁性有机材料做出重大贡献。该研究包括跨领域的调查，将通过暴露与有机光电和自旋电子材料和器件的发展相关的问题，为所涉及的研究生和本科生提供光学，电子和磁学方面的多学科培训。为了进一步提高其教育影响，该SGER将在田纳西大学为聚合物物理（MSE 543）和聚合物材料与器件的光电过程（MSE 674）开发新的课程。

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.