Using Circularly Polarized Light to Probe Electronic Excitations in Organic Supramolecular Assemblies

使用圆偏振光探测有机超分子组装体中的电子激发

• 批准号: 0906464
• 负责人: Francis Spano
• 金额: $ 30.6万
• 依托单位: Temple University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-15 至 2012-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0906464&HistoricalAwards=false
• 关键词: Using; Circularly; Polarized; Light; Probe

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).TECHNICAL ABSTRACTThis award is funded by the Division of Materials Research and the Chemistry Division. It supports theoretical research and education on how oligomer/polymer films interact with and emit light. The PI aims to investigate fundamental excitations in organic assemblies by focusing on chiral supramolecular structures which are amenable to circular dichroism and circularly polarized luminescence spectroscopies. Compared with their unpolarized counterparts, these spectroscopies are far more sensitive to extended intermolecular interactions as well as the structure of the fundamental electronic excitations. Of particular interest to this study are pi-stacked helical rod aggregates consisting of functionalized conjugated molecular chromophores which self-assemble in solution or with the aid of a DNA template. Specific goals include: 1. A detailed understanding of the excitonic signatures in the circularly polarized luminescence dissymmetry spectrum. The unusual demise of the spectrum with increasing wavelength observed in helical rod aggregates and chiral polymer films contains vital information on the anatomy of the emitting species. This spectrum is unique amongst spectral probes in its high sensitivity to the inner-sphere distortion field surrounding the core vibronic excitation. The objective is to understand how the polaron radius, the reorganization energy, and the coherence length impact the shape and magnitude of the circularly polarized luminescence dissymmetry spectrum. International collaboration with experimentalists will enable applications to oligothiophene nanofibers. 2. A rigorous analysis of intermolecular interactions in helical rod N-mers. Aggregates with a controllable number of chromophores are ideal systems with which to rigorously evaluate theoretical models for extended intermolecular interactions and disorder. The circularly polarized luminescence dissymmetry spectrum and its absorption analog are sensitive probes of long-range interactions even in strongly disordered systems where excitons are localized to only a few chromophores. The PI aims to perform a detailed theoretical analysis of the absorption spectrum to help resolve these issues. 3. An appreciation of the exciton Cotton effect in systems with strong exciton-phonon coupling. In assemblies with strong exciton-phonon coupling the circular dichroism spectrum is far more complex than the simple Cotton couplet found for weak coupling. The PI aims to develop a comprehensive theory for the circular dichroism response of excitonic polarons to understand how information regarding intermolecular interactions and the aggregate morphology can be extracted from the spectral line shape. Applications to the ubiquitous and biologically-important carotenoid aggregates will be made. The above analyses will be based on a Holstein Hamiltonian. Excitonic interactions, linear exciton-phonon coupling, and disorder will be treated on equal footing under the two-particle approximation, which reduces the basis set to a tractable size without sacrificing accuracy. The broader impact of the proposed activities will be felt primarily through an enhanced understanding of a technologically important class of materials, possibly resulting in novel design strategies for improved organic light-emitting diodes and 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 solid-state lighting. In addition, the proposed activities will enhance research infrastructure through international collaborations. NONTECHNICAL ABSTRACTThis award is funded by the Division of Materials Research and the Chemistry Division. It supports theoretical research and education on how thin films composed of a class of long chain molecules, polymers, interact with and emit light. The research is focused on key issues that impede understanding of the mechanisms by which these films interact with light, how light is absorbed by these materials and the nature of the electronic states after absorbing light. A key feature of the PI?s approach is to account for the interaction of electronic charge with vibrations of the molecular chains. Thin films of particular kinds of polymers may be useful as active materials for organic-based electronic devices such as transistors, light emitting diodes, and solar cells. This research project contributes to the intellectual foundations that will enable the use of these materials for lighting, solar energy conversion, and other electronic devices. 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 solid-state lighting. In addition, the proposed activities will enhance research infrastructure through international collaborations.

该奖项是根据2009年的《美国回收与再投资法》（公共法第111-5号）资助的。技术抽象奖由材料研究部和化学部门资助。它支持有关低聚物/聚合物膜如何与光线相互作用并发出光线的理论研究和教育。 PI旨在通过关注手性超分子结构来研究有机组件中的基本激发，这些结构可与圆形二科和循环极化的发光光谱镜一起进行。与它们的非极化对应物相比，这些光谱镜对扩展的分子间相互作用以及基本电子激发的结构更为敏感。这项研究特别感兴趣的是由PI堆叠的螺旋杆聚集体，这些螺旋杆聚集体由官能化的共轭分子发色团组成，它们在溶液中自组装或借助DNA模板。具体目标包括：1。对圆极化发光的不对称光谱中激素特征的详细理解。在螺旋杆聚集体和手性聚合物膜中观察到的波长增加的光谱的异常灭亡包含有关发射物种解剖结构的重要信息。该光谱在光谱探针之间是唯一的，其对核心振动激发周围的内球形失真场的高灵敏度。目的是了解极化子半径，重组能和相干长度如何影响圆形极化发光的不对称光谱的形状和幅度。与实验家的国际合作将使寡硫氰那纤维申请申请。 2。对螺旋杆N-Mers中分子间相互作用的严格分析。具有可控数量的发色团的聚集体是理想的系统，可以严格评估扩展分子间相互作用和混乱的理论模型。即使在强烈无序的系统中，激烈的相互作用的敏感探针也是激烈的探针的敏感探针，即即使在强烈无序的系统中，激烈的激发子被定位于仅几个发色团，也是远距离相互作用的敏感探针。 PI旨在对吸收光谱进行详细的理论分析，以帮助解决这些问题。 3。对具有强烈激子偶联的系统中激子棉效应的欣赏。在具有强烈激子 - 偶联的组件中，圆形二色性谱谱比发现的弱耦合的简单棉对联要复杂得多。 PI旨在为激子极性子的圆二色性响应开发一种综合理论，以了解如何从光谱线形状中提取有关分子间相互作用和骨料形态的信息。将对无处不在和生物学上最重要的类胡萝卜素聚集体进行应用。上述分析将基于荷斯坦哈密顿官。激子相互作用，线性激子 - phonon耦合和无序将在两个粒子近似下等基础上进行治疗，从而将设置的基础降低到可易于的尺寸而不牺牲准确性。提出的活动的更广泛影响将主要是通过对技术上重要的材料类别的理解来感受到的，这可能会导致新的设计策略，以改善有机发光二极管和太阳能电池。通过柔性显示器，电子标签和固态照明等产品，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。非技术摘要这一奖项由材料研究部和化学部门资助。它支持理论研究和教育，内容涉及一类长链分子，聚合物，与光线相互作用并发出光线的薄膜。这项研究的重点是阻碍对这些膜与光相互作用的机制的理解，这些材料吸收光线以及吸收光后电子状态的性质的理解的关键问题。 PI方法的关键特征是说明电子电荷与分子链振动的相互作用。特定类型的聚合物的薄膜可能可作为有机电子设备（例如晶体管，发光二极管和太阳能电池）的活性材料。该研究项目为智力基础做出了贡献，这些基础将使这些材料用于照明，太阳能转换和其他电子设备。通过柔性显示器，电子标签和固态照明等产品，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。