有机半导体的电子电离能、亲和势和极化能的密度泛函理论研究

发布时间：2018-01-17 14:28

本文关键词：有机半导体的电子电离能、亲和势和极化能的密度泛函理论研究　出处：《华东师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：近年来,由于具有轻便、可塑性好、制备方式灵活及生产成本低等优点,有机半导体材料受到了人们的广泛关注,成为研究的热点。为了设计新型有机半导体材料和理解相关机理,准确预测有机半导体的能级(如电子电离能和亲和势等)具有重要意义。从理论计算的角度看,首要的挑战来自于缺乏一种不仅能够在定性上合理而且在定量上精确预测,同时并不显著增加计算成本的理论方法。本论文中,我们为了准确预测有机半导体的能级参数率先提出了一种结合极化连续介质模型(PCM)和"最优调控"区间分离密度泛函的方法,并证明了该方法能够准确预测一系列有机半导体的电子电离能(IP),亲和势(EA)和极化能,其预测的结果能够很好地重现实验数据。重要的是,经过调控后分子的前线分子轨道能量(即-εHOMO和-εLUMO)与对应的IP和EA计算值十分接近。调控方法的成功可以进一步归因于其能够根据不同分子体系或同种分子所处的不同状态(气态和固态)"最优"地平衡泛函中分别用于描述电子局域化和离域化的作用。相比而言,其它常见的密度泛函方法由于包含的HF%比例过低(如PBE)或过高(如M06HF和未调控的区间分离泛函),均不能给予合理的预测。因此,我们相信这种PCM-调控的方法能够为研究其它更加复杂的有机体系的能级问题提供一种更加可靠和便捷的理论工具。论文的主要内容如下:第一章,综述了理论计算的发展、有机半导体的概念、分类以及代表性有机薄膜器件。此外,通过分析实验研究中的不足说明采用理论计算预测有机半导体IP和EA的必要性;第二章,简单介绍了密度泛函理论的发展,包括Thomas-Fermi模型、Hohenberg-Kohn定理、Kohn-Sham方程以及在此基础上发展出的各类密度泛函,继而引出最优调控密度泛函方法,并详细阐述了该方法的理论基础和发展过程;第三章,利用最优调控密度泛函方法和其它9种常见的密度泛函方法对气态和固态下分子的前线分子轨道能量(-εHOMO和-εLuMO)与IP和EA分别进行计算,并与已有的实验值进行比较,计算各参数理论计算值相对于实验值的平均绝对误差(MAD)大小并进行相应的误差分析。对比结果表明最优调控方法能够准确地预测上述能级参数和极化能,而其它泛函计算结果则存在不同程度的误差;第四章,总结了本论文的主要内容,并对进一步的研究做出展望。
[Abstract]:In recent years, organic semiconductor materials have attracted wide attention due to their advantages such as portability, good plasticity, flexible preparation and low production cost. In order to design new organic semiconductor materials and understand the related mechanism. It is important to accurately predict the energy levels of organic semiconductors (such as electron ionization energy and affinity potential). The primary challenge is the lack of a theoretical method that can not only be qualitatively reasonable but also quantitatively accurate, and does not significantly increase computational costs. In order to accurately predict the energy level parameters of organic semiconductors, we first proposed a method combining the polarization continuum model (PCM) and the "optimal regulation" region to separate the density functional. It is proved that this method can accurately predict the electron ionization energy (IP), affinity energy (EAA) and polarization energy of a series of organic semiconductors, and the predicted results can reproduce the experimental data well. Regulated frontier molecular orbital energy (i.e.-蔚 HOMO and-蔚 LUMOA). The success of the control method can be further attributed to its ability to operate in accordance with different molecular systems or different states of the same molecule (gaseous and solid). The "optimal" ground equilibrium Functionals are used to describe the effects of electron localization and delocalization, respectively. Other common density functional methods can not be reasonably predicted because the percentage of HF% included is too low (e.g. PBE) or too high (such as M06HF and unregulated interval separation functional). We believe that this PCM-regulation method can provide a more reliable and convenient theoretical tool for studying the energy level problems of other more complex organic systems. The main contents of this paper are as follows: chapter 1. The development of theoretical calculation, the concept, classification and representative organic thin film devices of organic semiconductors are reviewed. The necessity of predicting IP and EA of organic semiconductors by theoretical calculation is explained by analyzing the shortcomings of experimental research. In chapter 2, the development of density functional theory is briefly introduced, including the Hohenberg-Kohn theorem of Thomas-Fermi model. Kohn-Sham equation and all kinds of density functional developed on this basis, then the optimal control density functional method is derived, and the theoretical basis and development process of the method are described in detail. Chapter three. Using the optimal regulative density functional method and nine other common density functional methods, the orbital energies of frontier molecules in gaseous and solid state have been studied by means of 蔚蔚 HOMO and 蔚 Lumo. Calculate with IP and EA separately. And compared with the existing experimental values. The mean absolute error between the calculated values of each parameter theory and the experimental values / mad). The comparison results show that the optimal control method can accurately predict the above energy level parameters and polarization energy. Other functional results have different degrees of error. Chapter 4th summarizes the main contents of this paper and makes a prospect for further research.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O649.5;O641.1

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