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Theory and models for electronic dynamics in organic type II semiconductors

有机 II 型半导体中电子动力学的理论和模型

基本信息

批准号：
1362006
负责人：
Eric Bittner
金额：
$ 42万
依托单位：
University of Houston
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2014
资助国家：
美国
起止时间：
2014-09-01 至 2018-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1362006&HistoricalAwards=false
关键词：
Theory models electronic dynamics organic

项目摘要

Eric Bittner from the University of Houston is supported in an award by the Chemical Theory, Models and Computational Methods program in the Division of Chemistry and by the Condensed Matter and Materials Theory program in the Division of Materials Research to conduct research in charge and energy transport in photo-excited materials of interest for solar energy conversion. The goal of this work is to understand the behavior of electrons, nuclei, and light interacting in organic polymers, particularly those where the repeating parts of the polymers have small defects or are strongly disordered or come into contact with other materials. This work is to gain insight and advance materials design in energy applications and devices, e.g., plastic devices that generate electricity from sunlight. While quantum mechanical processes in these systems occur on an ultra short (10^-15 s) time scale, they directly influence device behavior emerging on longer time scales (mesoscales). However, lack of detailed understanding and control of these mesoscale processes has thus far prevented researchers from fully exploiting these effects. To this end, this research seeks understanding of how emergent phenomena arise due to interactions beyond on longer time and length scales.The Bittner group's work in this field is the development of advanced theoretical methods for studying charge and energy transfer processes initiated by the absorption of photons. The electronic and optical properties of conjugated macromolecules are due to the delocalized pi-electron systems involving strong electron correlations and coupling of electrons to molecular structure in oorganic semiconductors. This project explores how quantum coherence and quantum entanglement both impact the initial charge separation following photoexcitation and help to suppress subsequent recombination of charges once they have formed. The theoretical approach combines the use of lattice models to describe the mesoscale structure of polymer/fullerene bulk heterojunction interafaces -- parameterized using ab initio and experimental data -- and time-convolutionless master equation methods to describe non-adiabatic interstate electronic transition as driven by phonons. This approach is being benchmarked against a series of model donor-bridge-acceptor molecules originally studied by Closs and Miller in their classic work that confirmed the Marcus inverted regime. Other components include developing theoretical models for excitons/phonon polaritons in organic aggregates. Work is continuing in polariton Bose Condensation in J-aggregatea, especially in light of recent experiments by Bulovic's group at MIT. An additional aspect of the work is in the photophysics of excitons in confined geometries, where one can exploit the Purcell effect to prepare states that are otherwise inaccessible to experimental probes.

休斯敦大学的埃里克·比特纳 (Eric Bittner) 获得化学系化学理论、模型和计算方法项目以及材料研究系凝聚态和材料理论项目的资助，在太阳能转换感兴趣的光激发材料中进行电荷和能量传输研究。这项工作的目标是了解有机聚合物中电子、原子核和光相互作用的行为，特别是那些聚合物的重复部分具有小缺陷或严重无序或与其他材料接触的聚合物。这项工作是为了获得洞察力并推进能源应用和设备中的材料设计，例如利用阳光发电的塑料设备。虽然这些系统中的量子力学过程发生在超短（10^-15 s）时间尺度上，但它们直接影响在较长时间尺度（介观尺度）上出现的设备行为。然而，迄今为止，由于缺乏对这些中尺度过程的详细理解和控制，研究人员无法充分利用这些效应。为此，本研究旨在了解由于更长的时间和长度尺度上的相互作用如何产生涌现现象。比特纳小组在该领域的工作是开发先进的理论方法，用于研究由光子吸收引发的电荷和能量转移过程。共轭大分子的电子和光学性质是由于离域π电子系统涉及强电子相关性以及有机半导体中电子与分子结构的耦合。该项目探讨了量子相干性和量子纠缠如何影响光激发后的初始电荷分离，并有助于抑制电荷形成后的后续重组。该理论方法结合了使用晶格模型来描述聚合物/富勒烯本体异质结界面的介观结构（使用从头计算和实验数据进行参数化）和无时间卷积主方程方法来描述由声子驱动的非绝热态间电子跃迁。这种方法正在以一系列模型供体-桥-受体分子为基准，最初由克洛斯和米勒在他们的经典工作中研究，证实了马库斯倒置机制。其他组成部分包括开发有机聚集体中激子/声子极化激元的理论模型。 J-aggregatea 中的极化子玻色凝聚的研究工作仍在继续，特别是考虑到麻省理工学院 Bulovic 小组最近的实验。这项工作的另一个方面是受限几何结构中激子的光物理学，人们可以利用珀塞尔效应来制备实验探针无法达到的状态。