用激发子散射方法研究新型低维共轭分子体系的电子激发态

With the fast development of synthetic techniques, a large number of novel conjugated molecules have been created, which are potential materials for optoelectronic devices. It is desirable to understand and accurately predict excited state electronic structures for these molecules, as it forms the basis of design and optimization of conjugated materials. The Exciton Scattering Approach (ESA) is an efficient and accurate phenomenological method for dealing with the electronic excitations in conjugated systems. In ESA, excited states are treated as standing waves from exciton propagation (in linear parts) and scattering (at termini and nodes) in a conjugated system. Complex conjugated systems can be divided into a handful of building blocks, whose scattering parameters can be derived from either experiments or quantum calculations. ESA avoids the traditional direct electronic structure calculations, and it can be applied to any large system consisting of the characterized building blocks. Moreover, it maintains the accuracy of the data used for parameter extraction. The main purposes of this proposal are: 1. Continue to develop ESA. Incorporate phonon-exciton interaction, structural disorder, periodicity, etc. into ESA, so that more practical systems can be considered. 2. Apply ESA to novel low dimensional systems (nano wires, rings, and tubulars) and provide physical picture from a new perspective. 3. Setup a conjugated molecule database alongside ESA for fast design of novel optoelectronic materials.

共轭分子是制造光电设备的潜在材料，快速发展的合成技术促生了大量新型共轭分子，理解与准确预测共轭分子的电子激发态结构是设计与优化共轭分子材料的前提。激发子散射方法是一种高效准确的处理共轭体系激发态的唯象方法。它将复杂共轭体系的电子激发态看作激发子在该体系内的传播和散射所形成的驻波。复杂共轭体系可被分为有限的散射结构单元，相关的散射参数可以从实验或量子计算的结果中提取。该方法避免了传统的电子结构计算，能够处理由已表征的结构单元所组成的大分子体系，并且计算结果能够保持提取参数所用数据的精度。本项目申请主要是：一、继续发展激发子散射方法，使其能够处理声子-电子作用、结构缺陷、周期性结构等方面，即能够处理更现实的系统；二、将激发子散射方法应用于新的低维共轭体系（纳米线、圈、环等），从激发子散射的角度给出新的物理图象解释；三、初步建立共轭分子数据库，结合激发子散射方法，提供快速设计光电材料的工具。

本研究采用激发子散射方法对新的低维共轭体系（噻吩炔、噻吩烯、聚梯形对苯烯）进行了处理，得到相关散射矩阵的所需参数，并与以前研究过的聚苯乙炔体系进行了对比，证实“激发子散射方法”适用于具有不同拓扑、不同基本结构单元的体系。同时我们根据实际情况调整并扩充了研究内容，在表面/界面性质的应变工程调控方面（晶格失配下的晶体生长，表面催化反应等）初步取得了一系列成果，为今后的研究方向打开了新的局面。