卟啉修饰的Lindqvist型多酸杂化衍生物的电荷转移特征和吸收光谱的理论研究

发布时间：2018-06-18 03:31

本文选题：多金属氧酸盐 + 卟啉　；参考：《东北师范大学》2017年硕士论文

【摘要】：能源危机使环境污染越来越严峻,人类亟需寻求安全、清洁的可再生能源。在各类可再生能源中,光伏发电效能最长远。其中染料敏化太阳能电池(DSSC)因为低成本、高效率、制造工艺简单等优点而备受关注。染料敏化剂作为DSSC的光吸收剂,其性能的优劣直接影响电池的光电转换效率和光吸收效率。多金属氧酸盐,简称多酸(POM),是一类金属氧簇类化合物。它不仅结构稳定,而且还具有优异的光电性质,较强的吸电子能力,可以与有机基团结合形成具有良好光吸收性质的有机-无机杂化物,在DSSC中具备潜在的应用价值。本论文中,我们设计了多种多酸基有机-无机杂化物,采用密度泛函理论(DFT)和含时DFT(TDDFT)方法系统地研究了电子结构、吸收光谱和电荷转移特征,目的是探究其在DSSC中的应用。主要内容包括以下三部分:1.基于卟啉衍生物(体系1),设计了Lindqvist、Keggin、Anderson型多酸基有机-无机杂化衍生物(体系2-4)。采用DFT和TDDFT方法研究了体系1-4的电子结构、吸收光谱和电荷转移特征,筛选高效p-型染料。结果表明,Lindqvist和Keggin型多酸影响衍生物的最低空轨道能级和分布,而Anderson型多酸对衍生物的前线分子轨道没有贡献。Lindqvist型多酸卟啉衍生物(体系2)的吸收光谱在可见光区表现出强而宽的吸收,与体系1相比红移大约100 nm,有望成为性能良好的染料敏化剂。2.基于优异的染料敏化剂—苯乙炔基锌卟啉,设计了一系列锌卟啉多酸杂化物作为p-型染料敏化太阳能电池的敏化剂。为了揭示π桥对敏化剂性能的影响,采用DFT和TDDFT方法研究它们的吸收光谱和电荷转移特征。与体系1相比,体系2-5具有更长的π桥和更高的离域性,吸收光谱红移且拓宽。基于电荷转移量、电荷转移距离和空间电荷分离程度的电荷转移分析,结果表明,体系3达到了最大程度的电荷转移量和电荷分离度。此外,体系3的吸收光谱与太阳光谱重叠程度最大,有望成为良好性能的p-型染料敏化剂。3.为研究多酸对染料性能的影响,将Lindqvist型多酸引入实验合成的有机染料中,设计了一系列D-A-π-A型杂化物。基于DFT和TDDFT方法,系统研究了体系的电子结构、吸收光谱和电荷转移特征。与合成的染料对比发现,设计的染料分子光谱响应范围更大,其电荷转移方向均为给体向多酸和-COOH,证明染料与二氧化钛之间存在较强的电子耦合。电荷转移参数的分析表明,引入多酸后使染料的电荷转移能力增强。综合考虑光谱和电荷转移特征,WS-51-POM与太阳光谱的重叠面积最大,具有强的电荷转移能力,是潜在的优质染料敏化剂。
[Abstract]:Environmental pollution is becoming more and more serious due to the energy crisis, and human beings urgently need to seek safe and clean renewable energy. Among all kinds of renewable energy, photovoltaic power generation efficiency is the longest. Dye-sensitized solar cells (DSSCs) have attracted much attention because of their advantages of low cost, high efficiency and simple manufacturing process. As the optical absorbent of DSSC, the performance of dye sensitizer has a direct impact on the photovoltaic conversion efficiency and optical absorption efficiency of the battery. Polyoxometalate (POM) is a kind of metal oxygen cluster compound. It not only has stable structure, but also has excellent optoelectronic properties and strong electron absorption ability. It can be combined with organic groups to form organic-inorganic hybrids with good light absorption properties. It has potential application value in DSSC. In this paper, we have designed a variety of polyacid organic-inorganic hybrids. The electronic structure, absorption spectra and charge-transfer characteristics have been systematically studied by using density functional theory (DFT) and time-dependent DFT-TDDFTFT (time-dependent DFT-TDDFTFT). The purpose of this study is to explore their application in DSSC. The main content includes the following three parts: 1. Based on porphyrin derivatives (system 1), Lindqvistr Kegginn Anderson type organic-inorganic hybrid derivatives (system 2-4) were designed. The electronic structure, absorption spectrum and charge-transfer characteristics of 1-4 system were studied by DFT and TDDFT methods. The results show that Lindqvist and Keggin type polyacids affect the lowest empty orbital energy levels and distributions of derivatives. The absorption spectra of Anderson type porphyrin derivatives (system 2) showed strong and wide absorption in the visible region. Compared with system 1, the red shift is about 100 nm, which is expected to be a good dye sensitizer. 2. Based on the excellent dye sensitizer phenylethynyl zinc porphyrin a series of zinc porphyrin polyacid hybrids were designed as sensitizers for p- type dye sensitized solar cells. In order to reveal the effect of 蟺 -bridge on the properties of sensitizers, the absorption spectra and charge-transfer characteristics of the sensitizers were studied by DFT and TDDFT. Compared with system 1, system 2-5 has longer 蟺 -bridge and higher delocalization, and the absorption spectrum is red-shifted and broadened. The results of charge transfer analysis based on charge transfer quantity, charge transfer distance and the degree of space charge separation show that the system 3 achieves the maximum charge transfer quantity and charge separation degree. In addition, the absorption spectrum of system 3 has the greatest overlap with the solar spectrum, which is expected to be a good p- type dye sensitizer. 3. In order to study the effect of polyacid on the properties of dyes, Lindqvist polyacid was introduced into the organic dyes synthesized experimentally, and a series of D-A- 蟺 -A hybrids were designed. Based on the DFT and TDDFT methods, the electronic structure, absorption spectrum and charge transfer characteristics of the system were systematically studied. Compared with the synthesized dyes, it is found that the designed dyes have a larger spectral response range, and their charge transfer directions are donor polyacid and -COOH, which indicates that there is a strong electronic coupling between the dyes and TIO _ 2. The analysis of charge transfer parameters showed that the charge transfer ability of dyes was enhanced by the introduction of polyacids. Considering the spectral and charge-transfer characteristics, WS-51-POM has the largest overlapping area with the solar spectrum and has a strong charge transfer ability. It is a potential high quality dye sensitizer.
【学位授予单位】：东北师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O641.4;TM914.4

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