Optical Excitations in Conjugated Oligomer and Polymer Aggregates: A Computational Approach

0071802 spano这项资助支持这位职业生涯中期的PI在共轭聚合物薄膜的光吸收和发射方面的理论工作。本研究的重点是模型化合物低聚对苯乙烯和低聚噻吩及其衍生物的聚集体对光的吸收和发射。分析大致分为两种聚集体填充图案：(i)边对面填充，导致循环四聚体（风车）以及大人字形晶格，以及（ii）共面填充，导致p堆叠。聚集本征态是振动修饰的激子，主要由分子间能量（和/或电荷）转移的离域影响和分子内激发态核弛豫的局域影响之间的竞争决定。主要目的是了解激子-振动耦合和电荷分离程度如何影响光物理性质。该基金支持这位职业生涯中期的理论化学家对共轭聚合物薄膜中光发射和吸收现象的综合研究。预计在不久的将来，发光二极管和其他光电器件将由共轭聚合物薄膜制成。这很可能会在平板显示器上显示出来。聚合物薄膜可以通过光泵浦来发出激光，但也有希望通过电来发出激光。尽管设计了许多实验来揭示它们产生光的机制，但对聚合物薄膜中光发射的基本理解还远远没有完成，这主要是因为强烈的分子间相互作用的复杂存在。这里的研究将试图解决这些问题和其他相关问题

0071802SpanoThis grant supports the theoretical work of this mid-career PI on light absorption and emission from conjugated polymer films. The work here is focussed on the absorption and emission of light by aggregates of the model compounds, oligo- (p-phenylenevinylene) and oligo-thiophene and their derivatives. The analysis is broadly divided between two aggregate packing motifs: (i) edge-to-face packing, which leads to cyclic tetramers (pinwheels) as well as the large herringbone lattices, and (ii) cofacial packing, which leads to p stacks. The aggregate eigenstates are vibrationally dressed excitons, determined primarily by the competition between the delocalizing influence of intermolecular energy (and/or charge) transfer and the localizing influence of intramolecular excited state nuclear relaxation. The primary objective is to understand how exciton-vibrational coupling and the degree of charge separation influence photophysical properties.%%% This grant supports the work of this midcareer theoretical chemist in a comprehensive study of the phenomena of light emission and absorption in conjugated polymer films.It is expected that soon the light-emitting diodes and other optoelectronic devices will be made out of conjugated polymer films. This will show up, most likely, in flat panel displays. Polymer films can be made to lase via optical pumping although there is hope that they may lase electrically as well. Despite the many experiments designed to uncover the mechanism, by which they produce light, a fundamental understanding of light emission in polymer films is far from complete largely because of the complicating presence of strong intermolecular interactions. The research here will attempt to address these and other related issues***