有机半导体材料中电荷转移的理论研究

发布时间：2018-06-04 20:41

本文选题：有机半导体 + 第一性原理　；参考：《兰州大学》2015年硕士论文

【摘要】：有机半导体材料成为了目前研究的热点,因其具备可塑性好、多样的合成方法、易于加工及成本低等独特的优点。有机半导体已广泛地应用在有机晶体管、光学二极管、太阳能电池和生物化学传感器等器件上。而电荷转移是有机半导体器件中最为基本的过程,理论研究电荷转移机制具有重要的意义。本论文主要基于第一性原理并结合半经典的Marcus理论和全量子的费米黄金准则对有机半导体分子的电荷转移过程进行了研究,结合随机游走模型模拟了电荷迁移率。主要内容如下：1.采用一种全量子的理论结合分子动力学评估了五种共晶体系的双极性电荷转移性质。通过与传统的Marcus理论比较,证明了这种全量子的费米黄金准则更加适用于计算共晶分子的迁移率,这因为考虑了核隧道效应。计算表明这些共晶分子能够表现出良好的双极性的特征,这因为在主要传输方向上有着平衡的空穴和电子转移积分。同时我们证明了分子动力学对其迁移率也有显著地影响,这是因为给体.受体-给体和受体-给体-受体的超交换机制对分子动力学非常敏感。2.我们对并苯双噻吩、并苯双呋喃及并苯双硒酚系列分子DPh-NDXn (X= O,S,Se,n=1,2,3,4)单晶中的电荷转移进行了理论模拟。采用一种简单的方法对这系列分子DPh-NDXn的晶体结构进行了预测,并基于预测得到的晶体结构,模拟了系列分子的空穴迁移率。计算表明这些分子是一类极有前途的p型有机半导体分子。同时研究了不同杂原子和分子的形状对分子相关电学性质的影响。3.我们对实验室已经合成的吡嗪类氮杂并五苯及其衍生物系列分子的晶体结构迁移率进行了模拟。分析比较了薄膜模型和晶体模型的差异性,基于晶体模型模拟得到的迁移率结合实验结果分析表明随着N原子和卤素原子的引入,系列分子电荷传输性能有着显著的变化。4.对氟苯基修饰的四硫富瓦稀(TTF)系列衍生物分子的性质进行了研究。计算了其前线轨道能级、静电势分布等电学性质。研究了氟苯基上F原子的取代个数和空间取代位置的变化,对分子的HOMO和LUMO能级起到了调节作用。
[Abstract]:Organic semiconductor materials have become the focus of research, because of its good plasticity, various synthesis methods, easy to process and low cost and other unique advantages. Organic semiconductors have been widely used in organic transistors, optical diodes, solar cells and biochemical sensors. Charge transfer is the most basic process in organic semiconductor devices. It is of great significance to study the charge transfer mechanism theoretically. In this paper, the charge transfer process of organic semiconductors is studied based on the first principle, combined with the semi-classical Marcus theory and the full quantum Fermi gold criterion, and the charge mobility is simulated with the random walk model. The main content is as follows: 1. The bipolar charge transfer properties of five eutectic systems were evaluated by a full quantum theory combined with molecular dynamics. Compared with the traditional Marcus theory, it is proved that the full quantum Fermi gold criterion is more suitable for calculating the mobility of eutectic molecules because the nuclear tunneling effect is considered. The calculations show that these eutectic molecules exhibit good bipolarity due to the equilibrium of holes and electron transfer integrals in the main transport directions. At the same time, we prove that molecular dynamics also has a significant effect on its mobility, which is due to the donor. The superexchange mechanism of receptor-donor and receptor-donor-receptor is very sensitive to molecular dynamics. The charge transfer in Benzodithiophene, Benzobisofuran and Benzobisenol series molecules DPh-NDXn X = O ~ (2 +) S ~ (2 +) ~ (2) O ~ (3 +) has been theoretically simulated. A simple method is used to predict the crystal structure of the series of DPh-NDXn molecules, and based on the predicted crystal structure, the hole mobility of the series of molecules is simulated. The results show that these molecules are a promising class of p-type organic semiconductor molecules. At the same time, the influence of the shape of different heteroatoms and molecules on the electrical properties of molecular correlation was studied. We have simulated the crystal structure mobility of pyrazines and their derivatives. The differences between the film model and the crystal model are analyzed and compared. The results of mobility analysis based on the crystal model simulation show that the charge transport properties of the series of molecules vary significantly with the introduction of N atom and halogen atom. 4. The properties of fluorophenyl modified TTFs were studied. The energy levels and electrostatic potential distribution of the frontier orbital are calculated. The changes of the number of substituents and the space substitution positions of F atoms on fluorophenyl have been studied, and the HOMO and LUMO energy levels of the molecules have been regulated.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304

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