红荧烯体系结构、溶剂效应以及光电性能的密度泛函理论计算

发布时间：2018-03-23 23:39

本文选题：红荧烯及衍生物　切入点：密度泛函理论　出处：《郑州大学》2017年硕士论文

【摘要】：红荧烯(5,6,11,12-四苯基并四苯)是目前热门的有机半导体材料之一,常用于研究与制造各种功能材料及器件。但红荧烯也具有对光氧敏感等缺点,因此近些年,通过在红荧烯分子中引入不同的取代基设计开发具有优良性质的红荧烯衍生物,制备具有良好光电性质的功能材料,成为相关领域研究人员共同关注的焦点。引入取代基后,分子内的结构改变致使电子给体部分的最高被占用轨道(HOMO)与电子受体部分的最低未被占用轨道(LUMO)发生变化,从而改变能隙,同时结构变化不但改变分子的光学性质,也改变分子内的电荷转移程度。本文主要研究红荧烯及一系列衍生物在不同环境下的结构变化、谱带移动及光电性能,主要研究内容如下:首先介绍了有机电致发光材料、有机光致发电材料、有机电子传输材料,以及本文所研究的红荧烯体系和计算化学的背景,由于密度泛函理论是采用泛函求解薛定谔方程的电子结构理论方法,计算速度快且结果精确,因此适用于本文体系,并在此基础上运用溶剂效应理论、激发态理论和电子传输理论对本文体系进行理论计算。其次,利用上述理论和方法计算了红荧烯及三种衍生物在十二种溶剂中的红外谱图。通过添加极化连续模型(Polarization Continuous Model,PCM),得到四种分子在不同溶剂中的红外图谱,通过分析特征峰的移动和强度判断溶剂影响,发现红荧烯及衍生物分子在含质子溶剂中位移最明显,在极性官能团溶剂中的谱带位移次之,在醇类溶剂和惰性溶剂的位移较小。同时选用溶剂电子接受数AN、溶剂电子给予数DN、Dimroth溶剂参数ET(30)和Brownstein溶剂参数S四个溶剂参数分别与(5,12-二氟苯基-6,11-二苯甲氧基)并四苯分子的C-F键振动频率进行相关分析,相关性大小排序为SET(30)ANDN。然后,针对红荧烯及衍生物的光学性能进行系统的理论计算,研究取代基对分子几何构型、电离势、重组能、吸收光谱及发射光谱的影响。结果发现引入烷烃取代基,红荧烯及衍生物分子的吸收峰和荧光发射峰发生蓝移,而引入芳环取代基发生红移。茂基衍生物(R-Cp)分子吸收谱具有500-700 nm和300-500nm两处强吸收峰,更利于可见光的吸收,适合作为太阳能电池等光致发电材料。最后计算了红荧烯及衍生物分子的电学性能,分析前线分子轨道及能隙发现芳环取代基的引入利于形成激子。主链引入取代基有利于增强π共轭,支链引入则作用相反,因此主链引入芳环等共轭取代基可以降低分子能隙,得到电学性能更好的光电材料。分析电离势、电子亲和能和重组能发现三种衍生物分子R-Furan,R-Cp和R-OMe3适合做空穴半导体材料,R-F,R-OMe2,R-OMe1三种分子更适合做电子传输材料,而R-OMe4和R-Me两种分子的电子与空穴重组能差别较小,适合作为有机半导体晶体管中的发射材料。
[Abstract]:Red fluorene is one of the most popular organic semiconductor materials. It is often used in the research and manufacture of various functional materials and devices. However, red fluorene also has the disadvantages of being sensitive to photooxygen, so in recent years, By introducing different substituents into the red fluorene molecule to design and develop the red fluorene derivatives with excellent properties, the functional materials with good optoelectronic properties have become the common focus of researchers in related fields. Structural changes in the molecule result in changes in the maximum occupied orbital (HOMOO) of the electron donor and the lowest unoccupied orbit (LUMOO) in the electron acceptor, thus changing the energy gap, while the structural change not only changes the optical properties of the molecule, In this paper, the structure changes, band shift and photoelectric properties of red fluorene and a series of derivatives in different environments are studied. The main research contents are as follows: firstly, the organic electroluminescent materials are introduced. Organic photogenerated materials, organic electron transport materials, and the background of red fluorene system and computational chemistry studied in this paper, because density functional theory is an electronic structure theory method to solve Schrodinger equation, The calculation speed is fast and the result is accurate, so it is suitable for the system in this paper. On this basis, the solvent effect theory, the excited state theory and the electron transport theory are used to calculate the system. The infrared spectra of red fluorene and three derivatives in 12 solvents were calculated by using the above theory and method. The infrared spectra of four kinds of molecules in different solvents were obtained by adding polarization continuous model Polarization Continuous Model-PCM. By analyzing the shift and strength of the characteristic peaks, it is found that the shift of the red fluorene and its derivatives is the most obvious in the proton containing solvent, followed by the band shift in the polar functional group solvent. The displacements of alcohol and inert solvents were small. The solvent electron acceptors ANs, the solvent electron giving number DNN Dimroth solvent parameter ET30) and the Brownstein solvent parameter S were chosen to be different from the other four solvent parameters, respectively, which were 55-difluorophenyl-611-diphenylmethoxy). The vibrational frequency of C-F bond of tetraphenyl molecule was analyzed by correlation analysis. The order of correlation is set 30 and ANDN.Then, the theoretical calculation of the optical properties of red fluorene and its derivatives is carried out, and the geometric configuration, ionization potential and recombination energy of substituent pairs are studied. The influence of absorption and emission spectra. It was found that the absorption peak and fluorescence emission peak of red fluorene and its derivatives were blue shifted with the introduction of alkyl substituted groups. The absorption spectra of the chiral derivatives of R-Cp have strong absorption peaks at 500-700nm and 300-500nm, which is more favorable for visible light absorption. It is suitable for photovoltaic materials such as solar cells. Finally, the electrical properties of red fluorene and its derivatives are calculated. It is found that the introduction of substituents to aromatic rings is beneficial to the formation of excitons. The introduction of substituents in the main chain is beneficial to the enhancement of 蟺 conjugation, while the introduction of branched chains has the opposite effect. Therefore, the introduction of conjugated substituents such as aromatic rings in the main chain can reduce the molecular energy gap. By analyzing the ionization potential, electron affinity energy and recombination energy, it was found that the three derivative molecules, R-Furann, R-Cp and R-OMe3, were more suitable to be used as hole-semiconductor materials. However, the electron and hole recombination energies of R-OMe4 and R-Me have little difference, so they can be used as emitters in organic semiconductor transistors.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O649.5

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