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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.

来自休斯顿大学的Eric Bittner获得了化学系化学理论、模型和计算方法项目以及材料研究部凝聚态物质和材料理论项目的奖励，他在太阳能转换中感兴趣的光激发材料的电荷和能量传输方面进行了研究。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有小缺陷或强烈无序或与其他材料接触的聚合物。这项工作是为了在能源应用和设备中获得洞察力和推进材料设计，例如，从阳光中发电的塑料设备。虽然这些系统中的量子力学过程发生在超短（10^-15秒）的时间尺度上，但它们直接影响在较长时间尺度（中尺度）上出现的器件行为。然而，缺乏对这些中尺度过程的详细了解和控制，迄今为止阻碍了研究人员充分利用这些影响。为此，本研究寻求理解突现现象是如何在更长的时间和长度尺度上由于相互作用而产生的。Bittner小组在这一领域的工作是发展先进的理论方法来研究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有机半导体中涉及强电子相关性和电子与分子结构耦合的离域pi-电子系统。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。理论方法结合了使用晶格模型来描述聚合物/富勒烯体异质结界面的中尺度结构（使用从头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州际电子跃迁。这种方法正在与一系列模型供体-桥体-受体分子进行基准测试，这些模型最初是由克洛斯和米勒在他们的经典工作中研究的，该工作证实了马库斯倒立机制。其他组成部分包括建立有机聚集体中激子/声子极化子的理论模型。关于j -聚合体中极化子玻色凝聚的研究仍在继续，特别是根据麻省理工学院Bulovic小组最近的实验。这项工作的另一个方面是在受限几何中的激子的光物理学中，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。