蒽及其衍生物载流子传输性质的理论研究

发布时间：2018-04-23 07:01

本文选题：蒽及其衍生物 + 载流子传输　；参考：《吉林大学》2015年博士论文

【摘要】：有机光电功能材料由于其柔性、成本低、易调节性等优点而在过去的几十年中不管是在科学研究方面还是在应用领域中都得到了越来越多的关注。目前,有机光电功能材料被广泛地用来制备各种各样的光电子器件,如有机太阳能电池,有机发光二极管,有机场效应晶体管等。载流子迁移率是决定光电子器件性能的重要参数之一。设计合成出高迁移率的新型有机光电功能材料一直以来是一项艰巨任务。目前,科学工作者得到的有机新材料在室温下的薄膜迁移率已经高达1~10cm2/V·s,在单晶中迁移率更高。有机光电功能材料的载流子传输性质的理论研究可以追溯至二十世纪五十年代。1959年,Holstein提出了描述有机固体材料中电子运动的小极化子模型,但由于在求解过程中,无法评估近似的应用性而限制了其应用。另一方面,B?ssler等人提出了描述有机电子器件的无序模型。从微观角度来看,主要有两类载流子传输模式:描述离域电子的连续模型和描述定域电子的跃迁模型。这其中Brédas等人基于半经典的Marcus电子转移理论和第一性原理计算,通过分子间的传输积分和分子的重组能的计算来预测载流子传输性质,得到了广泛的应用。本文正是基于这一理论,选取了有机小分子蒽及其衍生物9,10-二(邻,间,对)吡啶乙烯基蒽的晶体为研究对象,研究了分子的几何构型,分子前线轨道,重组能,传输积分,载流子迁移率等特性,优化了理论方法,阐明了分子几何构型和分子间相互作用与材料载流子传输性质之间的关系。主要研究内容及结果如下:首先,我们选取了经典的有机小分子蒽的晶体为研究对象,基于密度泛函理论(DFT)方法,采用B3LYP/6-31(d,p)基组研究了蒽晶体的分子结构,重组能,基于PW91PW91/6-31(d,p)基组计算了电荷传输积分,最后通过Einstein方程得到了蒽晶体的载流子迁移率,其空穴迁移率为0.662cm2/V·s,电子迁移率为0.590cm2/V·s。结果表明,理论计算得到的载流子迁移率处于实验结果数值范围内,说明我们采用的理论方法是准确可行的;与其他理论计算结果相比较可知,适宜的理论计算方法以及尽可能准确的传输积分路径,可以确保得到准确性可靠的理论计算结果。其次,我们基于密度泛函理论,系统研究了9,10-二(邻间对)乙烯基蒽衍生物BP2VA,BP3VA和BP4VA的电子结构和载流子传输性质,他们的不同之处在于9,10-二乙烯基蒽和吡啶间的链接方式分别为邻位、间位和对位。计算结果表明,对于这三种晶体来说,理论计算的空穴迁移率约是电子迁移率的几十倍。9,10-二乙烯基蒽和吡啶之间邻、间、对的链接方式不仅影响着了分子的几何构型,进而导致重组能的不同,而且还影响了分子间相互作用,进而导致传输积分的不同,从而对材料的载流子迁移率产生了很大影响。BP2VA,BP3VA和BP4VA的载流子迁移率的数值具有一致的变化趋势,即BP4VABP2VABP3VA,表明9,10-二乙烯基蒽和吡啶间对位的链接方式能够有效降低晶体形态中周围分子的空间位阻效应。对于BP4VA来说,我们计算得到了约为1 cm2/V·s的空穴迁移率。研究结果对于设计合成具有高载流子迁移率的有机半导体材料,尤其是对于具有多个功能团,且功能团间可以通过邻间对的链接方式相连的有机半导体材料,具有一定的指导意义。最后,我们基于Marcus电荷传输理论研究了具有三种不同晶体结构(α-,β-,γ-BP2VA)的BP2VA分子材料的载流子传输性质。通过对重组能、传输积分和迁移率的计算和分析,阐明了BP2VA分子电荷传输性质与晶体结构间的关系:(1)三种晶体结构类型均有利于空穴的传输,其中β-BP2VA晶体结构的空穴迁移率高达~1 cm2/V·s。(2)分子间呈错位共面的π堆积结构,适当的中心距离,分子轨道同相且重叠,分子间存在弱相互作用等可以获得较大的传输积分数值,从而获得较高的载流子迁移率。(3)气态下单个分子的重组能和考虑到周围近邻分子的空间效应后的镶嵌分子的重组能的比较可知,BP2VA分子的重组能依赖于分子间的相互作用。上述研究结果有助于我们更加深入地了解电荷传输性质与有机半导体材料结构之间的关系,对于设计高载流子迁移率的有机光电功能材料具有十分重要的意义。
[Abstract]:Organic optoelectronic functional materials have attracted more and more attention in the past few decades because of their flexibility, low cost, and easy to adjust. Organic optoelectronic functional materials are widely used to produce a variety of optoelectronic devices, such as organic solar cells, in the past few decades. Organic light-emitting diodes, with an airport effect transistor, etc.. Carrier mobility is one of the important parameters determining the performance of optoelectronic devices. It has been a difficult task to design a new organic photoelectric functional material with high mobility. At present, the film mobility of organic new materials obtained by scientists at room temperature has been high. The mobility of 1~10cm2/V. S is higher in single crystal. The theoretical study of carrier transport properties of organic photoelectric functional materials can be traced back to.1959 in 1950s. Holstein has proposed a small polaron model describing the electron movement in organic solid materials, but it is limited to the approximate application in the process of solving the solution. On the other hand, B? Ssler et al. Put forward a disordered model for describing organic electronic devices. From a microscopic point of view, there are two main types of carrier transport modes: a continuous model describing the off domain electrons and a transition model describing the localized electrons. In this, the Br e Das et al. In the semiclassical Marcus electron transfer theory and the first original It has been widely used to predict the carrier transport properties by calculating the transport integral between molecules and the calculation of the recombination energy of molecules. This paper is based on this theory. The crystal of pyridine anthracene, an organic small molecule anthracene and its derivative, 9,10- two (neighbouring, pair), is selected as the research object, and the geometric configuration of the molecule is studied. The theoretical method is optimized and the relationship between the molecular geometric configuration and intermolecular interaction with the carrier transport properties is clarified. The main contents and results are as follows: first, we select the classical organic anthracene crystal as the research object. In density functional theory (DFT) method, the molecular structure and recombination energy of anthracene crystal are studied by B3LYP/6-31 (D, P) base group. The charge transfer integral is calculated based on PW91PW91/6-31 (D, P) base group. Finally, the carrier mobility of anthracene crystal is obtained by the Einstein equation. The mobility of the hole is 0.662cm2/V s, and the electron mobility is 0.590cm2/V S. junction. The results show that the carrier mobility of the theoretical calculation is within the numerical range of the experimental results, indicating that the theoretical method we adopted is accurate and feasible. Compared with the other theoretical calculation results, the suitable theoretical calculation method and the possible accurate transfer of integral path can ensure the accurate and reliable theoretical calculation knot. Secondly, based on the density functional theory, we systematically studied the electronic structure and carrier transport properties of 9,10- two (adjacent pair) vinyl anthracene derivatives BP2VA, BP3VA and BP4VA. Their differences lie in that the links between 9,10- two vinyl anthracene and pyridine are adjacent, interposition and counterpart respectively. The results show that the three crystals are for these three crystals. In body, the hole mobility of theoretical calculation is approximately a few times the electron mobility of.9,10- two vinyl anthracene and pyridine. The link mode not only affects the geometry of the molecules, but also leads to the difference of the recombination energy, but also affects the intermolecular interaction, which leads to the difference of the transfer integral and thus the material. The carrier mobility has a great influence on.BP2VA, the carrier mobility of BP3VA and BP4VA has a consistent change trend, that is, BP4VABP2VABP3VA. It shows that the link between 9,10- two vinyl anthracene and pyridine counterpart can effectively reduce the space hindrance effect of the surrounding molecules in the crystal morphology. For BP4VA, we calculate the results. The hole mobility about 1 cm2/V. S. The results have a definite guiding significance for designing organic semiconductor materials with high carrier mobility, especially for multiple functional groups, and the organic semiconductors that can be linked by adjacent pairs between functional groups. Finally, we are based on the Marcus charge. The transport theory has been carried out to study the carrier transport properties of the BP2VA molecular material with three different crystal structures (alpha, beta, gamma -BP2VA). Through the calculation and analysis of the recombination energy, the transfer integral and the mobility, the relationship between the charge transfer properties of the BP2VA molecules and the crystal structure is clarified. (1) the three types of crystal structures are beneficial to the transmission of the holes. The hole mobility of the crystal structure of the beta -BP2VA is as high as that of ~1 cm2/V. S. (2) is a pion stacking structure with the dislocation coplanar between the molecules, the proper center distance, the molecular orbital phase and overlap, the existence of the weak interaction between the molecules and so on, which can obtain a higher carrier mobility. (3) a single molecule in the gaseous state. The recombination energy and the comparison of the recombination energy of the mosaics after taking into account the spatial effect of adjacent adjacent molecules can be found that the recombination of BP2VA molecules can depend on the intermolecular interaction. The above results will help us to understand the relationship between the charge transport properties and the structure of the organic semiconductors, and to design a high carrier. Organic photoelectric functional materials with mobility are of great importance.

【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB34;O625.154

【相似文献】