Modeling Molecular Aggregate Photophysics in Free Space and in Optical Microcavities

模拟自由空间和光学微腔中的分子聚集体光物理

基本信息

批准号：
1810838
负责人：
Francis Spano
金额：
$ 31.35万
依托单位：
Temple University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-12-01 至 2022-11-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1810838&HistoricalAwards=false
关键词：
Modeling Molecular Aggregate Photophysics Free

项目摘要

NONTECHNICAL SUMMARYThis award supports theoretical and computational research and education on how light is absorbed or emitted from semiconductor materials made of organic molecules. The most familiar semiconductor is probably silicon which is used in microelectronics and the chips inside modern computers. However,semiconductors based on organic molecules continue to make inroads into commercial devices, such as organic light-emitting diodes or OLEDs. Thin organic films can be driven electrically to emit light or can be used to convert solar energy into electrical energy. The PI and his research team will investigate the fundamental processes in organic crystals or aggregates when they absorb and emit light. The PI will also investigate how absorbed energy is transported between molecules which is similar to how plants transport energy during the process of photosynthesis. The research team will conduct a theoretical investigation by solving equations based on quantum mechanics which describe how organic molecules respond to light. The equations will be solved using sophisticated computer algorithms. The PI will also investigate the effect of enclosing a thin organic film in a very small "micro" cavity formed by two reflecting mirrors separated by a tiny distance equal to about a wave length of light. A microcavity enhances the interaction between light and the enclosed molecules and can dramatically alter the behavior of the enclosed organic film, allowing one to better control its optical properties. The proposed activities will also enhance research infrastructure through domestic and international collaborations involving Professor Libai Huang at Purdue University, who will employ state-or-the-art experimental techniques to probe energy transport in organic films, and Dr. Felipe Herrera at the University of Santiago, Chile, who will assist in the theoretical investigations of organic microcavities. Overall, this research effort should contribute to a blueprint for the next generation of electronic devices based on organic materials.TECHNICAL SUMMARYThis award supports theoretical and computational research and education on how light is absorbed or emitted from semiconductor materials made of organic molecules. Solid phases of pi-conjugated molecules and polymers continue to receive widespread attention as semiconducting materials in field effect transistors, light emitting diodes, and solar cells. However, despite the more than five decades of intensive experimental and theoretical research following Kasha's pioneering work on H- and J-aggregates, there remain important questions regarding the nature of the photo-excitations in molecular aggregates and how the optical response is related to crystal packing and morphology. The PI and his research team have recently extended Kasha's model, which is predicated entirely on long-range Coulombic coupling, to include short-range (super-exchange) coupling arising from intermolecular charge-transfer in packing arrangements hosting close intermolecular contacts. Although the model can predict with quantitative accuracy details of the absorption spectral line shape, it is limited in its ability to describe energy transport, as it does not account for excimers, which are commonly encountered in many dye aggregates and crystals. Excimers, which can trap energy and limit transport, arise when an optically-excited state couples strongly to an intermolecular coordinate. Hence, a primary goal of the PI's research activity is to expand the post-Kasha model to include excimers. The approach is based on a multi-particle representation of a Holstein-style Hamiltonian which is superior to most others in that it treats all the important physical processes including exciton coupling, the mixing between Frenkel and charge-transfer excitons, exciton-vibrational coupling, and exciton-photon coupling, on equal footing. The essentially exact treatment of physical observables within a large phase space enhances the likelihood for discovering new and potentially useful physical phenomena. With quantitative reproductions of both the absorption and photoluminescence spectra in hand, predictions of the efficiency of exciton transport will be made. The Huang Group at Purdue will provide the experimental validation by conducting femtosecond-resolved transport measurements of several perylene diimide (PDI) derivatives with varying degrees of excimer emission. In another thrust, the PI will investigate the behavior of organic materials inside optical microcavities, where a strong cavity field can be used to control the mixing between material eigenstates. Of particular interest is the possibility of modulating the mixing between Frenkel and charge-transfer excitons, thereby controlling the formation of excimers. In addition, the fundamental photophysical properties of the recently discovered "dark" polaritons - composite quasiparticles consisting of a mixture of electronic, photonic and vibrational degrees of freedom - will be explored in collaboration with Felipe Herrera at the University of Santiago, Chile. The analyses will be based on Holstein-style Hamiltonians for free-space and cavity-confined molecular aggregates represented in a multi-particle basis set sufficient for obtaining highly accurate spectral and transport observables. Overall, the project has the potential to significantly advance our understanding of i) the relationship between molecular aggregate properties, particularly photophysics and transport, and packing morphology; ii) the way microcavity coupling can be exploited as a means for controlling super-exchange coupling and excimer formation in pi-stacks and iii) novel types of polaritons involving all three degrees of freedom, electronic, vibrational, and photonic.This award is jointly supported through the Condensed Matter and Materials Theory Program in the Division of Materials Research and the Chemical Theory, Models and Computational Methods Program in the Chemistry Division.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术摘要这一奖项支持理论和计算研究和教育，以从有机分子制成的半导体材料中吸收或发射光。最熟悉的半导体可能是硅，用于微电子和现代计算机内的芯片。但是，基于有机分子的半导体继续侵入商业设备，例如有机发光二极管或OLED。薄的有机膜可以电动驱动以发出光，也可以用于将太阳能转化为电能。 PI和他的研究团队将在吸收和发光时研究有机晶体或聚集的基本过程。 PI还将研究如何在分子之间传输吸收能量，这与植物在光合作用过程中如何运输能量相似。研究小组将通过基于量子力学的方程来进行理论研究，该方程描述了有机分子如何对光的反应。方程将使用复杂的计算机算法解决。 PI还将研究将薄有机膜封闭在非常小的“微型”腔中的效果，该腔由两个反射镜形成，其小距离被相当于波长的波长。微腔增强了光与封闭分子之间的相互作用，并可以大大改变封闭的有机膜的行为，从而更好地控制其光学特性。拟议的活动还将通过涉及普渡大学的Libai Huang教授的国内和国际合作来增强研究基础设施，后者将采用国家或艺术实验技术来探测有机电影中的能源运输，以及智慧大学的圣地亚哥大学Felipe Herrera博士，他们将协助有机化的有机学研究。总体而言，这项研究工作应为基于有机材料的下一代电子设备的蓝图做出贡献。技术摘要这一奖项支持理论和计算研究以及有关如何从有机分子制成的半导体材料中吸收或发射光的理论和计算研究。随着现场效应晶体管，光发射二极管和太阳能电池的半导体材料，PI共轭分子和聚合物的实心阶段继续受到广泛的关注。然而，尽管在Kasha开创性的H-和J种群的开创性工作之后进行了五十多年的密集实验和理论研究，但关于分子聚集体中光筛分的性质以及光学响应与晶体包装和晶体包装和形态的重要性仍然存在重要问题。 PI和他的研究团队最近扩展了Kasha的模型，该模型完全基于远程库仑耦合，其中包括由分子间电荷转移在包装安排中引起的短距离（超交换）耦合，托管紧密分子间接触。尽管该模型可以通过定量准确性的细节来预测吸收光谱线形状的细节，但它的描述能力传输的能力受到限制，因为它不考虑精确剂，而这些准分子通常在许多染料聚集体和晶体中通常遇到。当光学兴奋的状态夫妻强烈地与分子间坐标时，会产生可能捕获能量并限制运输的准分子。因此，PI研究活动的主要目标是将喀沙后模型扩展到包括准分子。该方法基于荷斯坦风格的哈密顿量的多粒子表示，该代表比大多数其他大多数人都优越，因为它处理了所有重要的物理过程，包括激子耦合，Frenkel和Charge-Transfer-Transfer Excitons，Ickiton-Exciton-Exciton-Exciton-Excitation-Excitation-Excitation-Excitational-Excitational-Photational-Photon-Photon-Photon-Photon-Photon-Photon-Photon-Photon-Photon Couplats coupling coupling coupling coupling coupling coupling，coupling coupling coupling coupling coupling coupling。在大相空间内对物理可观察物的基本确切处理增强了发现新的且潜在有用的物理现象的可能性。随着手头吸收和光致发光光谱的定量复制，将对激子运输的效率进行预测。普渡大学（Purdue）的Huang组将通过对几个二酰亚胺（PDI）衍生物进行不同程度的准分子发射的几个二酰亚胺（PDI）衍生物进行飞秒的分辨转运测量。在另一个推力中，PI将研究光学微腔内有机材料的行为，其中可以使用强腔场来控制材料特征状态之间的混合。特别令人感兴趣的是可能调节Frenkel和电荷转移激子之间的混合，从而控制准分子的形成。此外，将与智利圣地亚哥大学的Felipe Herrera合作探索最近发现的“深色”极性元素的基本光物理特性 - 由电子，光子和振动自由度的混合物组成的复合材料准颗粒。这些分析将基于荷斯坦风格的哈密顿量的自由空间和腔体限制的分子聚集体，这些分子聚集体以多粒子为基础表示，足以获得高度准确的光谱和运输观测值。总体而言，该项目有可能显着促进我们对i）分子骨料特性，尤其是光体物理学和运输以及包装形态的关系； ii）可以利用微腔耦合作为控制超级交换耦合的一种手段和PI堆和III中的超级交换耦合和进取的形成），涉及所有三个自由，电子，振动和光子奖的新型极性类型。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响标准来评估值得支持。