Optical Excitations in Supramolecular Assemblies of Conjugated Oligomers and Polymers

共轭低聚物和聚合物超分子组装体中的光激发

• 批准号: 0606028
• 负责人: Francis Spano
• 金额: $ 24万
• 依托单位: Temple University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-15 至 2010-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0606028&HistoricalAwards=false
• 关键词: Optical; Excitations; Supramolecular; Assemblies; Conjugated

Thin films of pi-conjugated polymers and their oligomer progeny continue to receivewidespread attention as the active materials for organic-based field effect transistors, lightemitting diodes (OLEDs) and solar cells. Despite the many experiments designed to reveal the mechanism(s) by which oligomer/polymer films interact with light, a fundamental appreciation of the relationship between solid-state morphology and photophysical behavior is lacking. In this renewal proposal a strategy is outlined for theoretically investigating an emerging class of supramolecular assemblies based on oligo-p-phenylenevinylene (OPVn) and oligo-thiophene (OTn) derivitives. Side- and end-group functionalization induces chirality and hydrogen bonding in self-assembled nanostructures including helical rod aggregates, rosette shaped aggregates and two-dimensional lamellae. Many of these structures employ p-stacking motifs whichcomplement the more common herringbone packing found in crystals and thin films of the unsubstituted OPVn and OTn molecules. Specific goals include: A detailed understanding of the impact of exciton delocalization, exciton-phonon coupling and disorder on the photo-excited and photo-emissive states in chiral aggregates. Abundant spectral data for helical rod aggregates including steady-state absorption, photoluminescence, circular dichroism (CD) and circularly polarized luminescence (CPL), allows rigorous testing of theoretical models featuring various scenarios for static disorder. A global account for the unusual demise of the CPL dissymmetry magnitude with increasing wavelength observed in OPVn-based helical rod aggregates as well as chiral polythiophene thin films is sought.A robust theoretical account of the deleterious effect of increasing oligomer length on theexciton bandwidth observed in a series of ethylene oxide end-capped OTn fibrillar aggregates (with n=5,6,7). How the bandwidth behaves into the polymer limit is crucial in understanding energy transport and optical properties in thin films of the technologically important regioregular poly(3-alkylthiophenes).Accurate modeling of rapid picosecond energy transport in helical rod aggregates as well as the temporal evolution of the emission spectral line shape following excitation abovethe optical gap. The emission spectral line shape provides valuable information about high energy emissive states. The analysis will be based on the Holstein Hamiltonian, treating excitonic interactions, linear exciton-vibrational coupling, and the influence of point and structural defects on equal footing. The two-particle approximation will be employed to reduce the basis set to a tractable size for numerical analysis without sacrificing accuracy. Excitonic polarons and their steady-state spectral signatures will be evaluated using standard numerical matrix techniques. A Pauli Master Equation will be employed for the exciton transport studies.The broader impact of the proposed activities will be felt primarily through an enhancedunderstanding of a technologically important class of materials, possibly resulting in novel design strategies for improved OLEDs and organic-based solar cells. The commercial impact of soft electronic devices is expected to dramatically increase over the next several years, through products like flexible displays, electronic labels and even solid-state lighting. In addition, the proposed activities will enhance research infrastructure through international collaborations. (D. Beljonne at the Universite de Mons, Belgium; S. Meskers at Eindoven University, The Netherlands; and C. Silva at the University of Montreal.)Non-Technical Abstract: This grant will support theoretical research on the properties of thin films of electrically active polymers. These materials have potential applications as components of electronic devices ("electronic plastics"). However, much needs to be done to understand their fundamental behavior. The work proposed here involves international collaborations with others working on these problems and provides wonderful learning opportunities for students and postdoctoral associates working on this project.

PI结合聚合物及其低聚物后代的薄膜继续受到广泛的关注，因为有机田间效应晶体管的活性材料，亮光二极管（OLEDS）和太阳能电池。尽管许多实验旨在揭示低聚物/聚合物膜与光相互作用的机制，但缺乏对固态形态与光物理行为之间关系的基本欣赏。在此续签建议中，概述了一种策略，用于从理论上研究基于寡-P-苯基乙烯（OPVN）（OPVN）和寡噻吩（OTN）衍生物的新兴超分子组件。侧和端组功能化在包括螺旋杆骨料，玫瑰花结骨料和二维薄片的自组装纳米结构中诱导手性和氢键。这些结构中的许多采用了P堆积基序，这些基序是在未取代的OPVN和OTN分子的晶体和薄膜中发现的更常见的人字形堆积。具体目标包括：详细了解激子离域，激子 - phonon耦合和混乱对手性骨料中照相和光发射状态的影响。螺旋杆聚集体的丰富光谱数据，包括稳态吸收，光致发光，圆形二色性（CD）和圆形极化发光（CPL），可以严格测试具有静态疾病各种场景的理论模型。寻求CPL不对称程度的异常灭亡，在基于OPVN的基于OPVN的螺旋杆聚集体中观察到的波长增加以及手性的聚噻吩薄膜。 n = 5,6,7）。带宽如何表现到聚合物极限对于理解技术重要的晶状体晶状体薄膜中的能量传输和光学特性至关重要。在螺旋杆聚集体以及发射光谱线形状的时间进化的螺旋杆骨料中，快速的picosecond能量传输的准确模型在旋转杆骨料中的快速型能量转运。 发射光谱线形状提供了有关高能发射状态的有价值信息。 该分析将基于荷斯坦汉密尔顿人，处理激子相互作用，线性激子 - 振动耦合以及点和结构缺陷对相等基础的影响。 两粒子近似将用于将基集设置减少到可拖动的大小以进行数值分析而不牺牲准确性。激子极地及其稳态光谱特征将使用标准数值矩阵技术进行评估。 Pauli Master方程将用于激子运输研究。拟议活动的更广泛影响主要是通过对技术重要的材料类别的增强感受到的，这可能会导致改善OLED和有机太阳能电池的新型设计策略。通过柔性显示器，电子标签甚至固态照明，预计软电子设备的商业影响将在未来几年内急剧增加。此外，拟议的活动将通过国际合作来增强研究基础设施。 （比利时蒙斯大学的D. Beljonne；荷兰Eindoven University的S. Meskers；蒙特利尔大学的C. Silva。 这些材料具有潜在的应用，作为电子设备的组成部分（“电子塑料”）。 但是，要理解其基本行为，需要做很多事情。 这里提出的工作涉及与其他从事这些问题的其他人的国际合作，并为从事该项目的学生和博士后员工提供了绝佳的学习机会。