新型芳胺类光敏染料的理论与实验研究

发布时间：2019-05-30 02:22

【摘要】：随着煤炭、石油、天然气等不可再生能源的枯竭,人们开始意识到可再生能源开发的重要性。在可再生能源中,太阳能以其安全、卫生、清洁、资源充足和应用广泛等显著优点逐渐成为人们关注的热点。1991年,瑞士联邦高工的Gr?tzel研究小组发明了一类新型太阳能电池—染料敏化太阳能电池(Dye-Sensitized Solar Cells,DSSCs),该类电池克服了传统太阳能电池制作工艺复杂、成本昂贵等缺点,并获得了高达13%的光电转换效率。在DSSCs中,光敏染料的光致激发、电子由染料向二氧化钛(Ti O2)导带的注入和氧化态光敏染料的还原等重要过程均发生在染料/TiO2光阳极界面上,所以研究这一界面对于提高DSSCs光电性能有着重大的意义。基于此,本论文开展了以下两方面的研究:一、探索高效的新型光敏染料,二、研究溶剂效应对于染料/TiO2光阳极界面的影响。1.光敏染料是染料/TiO2光阳极的重要组成部分,起着捕获光子产生激发态电子的重要作用。为了高效、快捷地寻找高性能的光敏染料,采用密度泛函理论计算对所设计的四硫富瓦烯(TTF)、吩噻嗪、咪唑等三类芳胺光敏染料进行理论筛选。研究结果表明,TTF可以作为光敏染料的良好电子给体,它的引入能够极大增加光敏染料的光捕获能力。通过对吩噻嗪光敏染料共轭桥的修饰,能扩宽此类光敏染料的光吸收范围从而提高光电转换效率。所设计的咪唑类分子适合作为光敏染料,并具有结构简单、易于制备的特点,有益于后续工作的开展,所以后续章节的研究均基于此类光敏染料。2.制备理论筛选的咪唑类目标光敏染料,并将其组装成DSSCs进行研究。采用理论与实验结合的研究方法,探讨了四种CD染料的光物理、电化学性质以及相应DSSCs的光电性能,并在原子层面上对此类光敏染料的性能差异给予了微观解释。基于CD-4、CD-5的电池器件分别获得了1.89和0.61%的光电转换效率。进一步,在CD-4、CD-5结构中引入三苯胺基团制备的CD-7、CD-8获得了更为高效的光电性能,电池的光电转换效率分别为4.11和1.51%。研究表明,染料光电性能的改善是由于三苯胺基团的引入增强了光敏染料的光捕获能力和空间位阻作用。3.基于制备的咪唑光敏染料CD-6,选取THF、DMF为溶剂,研究了溶剂效应对于染料/TiO2光阳极界面以及DSSCs光电性能的影响。以THF、DMF为敏化溶剂制备的电池分别获得了1.53和0.83%的光电转换效率。实验结果表明,在THF中,CD-6敏化TiO2薄膜的吸收范围更广且染料分子吸附密度更大,最终获得了更好的光电性能。并采用DFT理论模拟了THF、DMF对CD-6在TiO2表面吸附形貌的影响,在原子层面解释了电池的性能差异。
[Abstract]:With the depletion of non-renewable energy such as coal, oil, natural gas and so on, people begin to realize the importance of renewable energy development. In renewable energy, solar energy has gradually become the focus of attention because of its remarkable advantages, such as safety, sanitation, cleanliness, sufficient resources and wide application. The Swiss federal high-tech Gr?tzel research team has invented a new type of solar cell-dye-sensitized solar cell (Dye-Sensitized Solar Cells,DSSCs). This kind of cell has overcome the shortcomings of traditional solar cell, such as complex fabrication process, high cost and so on. The photoelectric conversion efficiency of up to 13% is obtained. In DSSCs, the photoexcitation of Guang Min dye, the injection of electrons from dye to titanium dioxide (TiO2) conduction band and the reduction of oxidized Guang Min dye occur on the dye / TiO2 photoanode interface. Therefore, it is of great significance to study this interface to improve the photoelectric performance of DSSCs. Based on this, the following two aspects have been studied in this paper: first, to explore the new type of Guang Min dye with high efficiency, and second, to study the effect of solvent effect on the interface of dye / TiO2 photoanode. Guang Min dye is an important part of dye / TiO2 photoanode, which plays an important role in trapping photons to produce excited electrons. In order to find high performance Guang Min dye efficiently and quickly, three kinds of arylamine Guang Min dyes, such as tetrathiafulvalene (TTF), phenothiazide and imidazole, were selected theoretically by density functional theory (DFT). The results show that TTF can be used as a good electron donor for photoperiod sensitive dye, and its introduction can greatly increase the light capture ability of photosensitive dye. By modifying the conjugated bridge of phenothiazin photosensitive dye, the optical absorption range of this kind of Guang Min dye can be broadened and the photoelectric conversion efficiency can be improved. The imidazole molecules designed are suitable for Guang Min dye, and have the characteristics of simple structure and easy preparation, which is beneficial to the development of follow-up work, so the research in the following chapter is based on this kind of Guang Min dye. 2. The imidazole target Guang Min dye selected by theory was prepared and assembled into DSSCs for study. The photophysical and electrochemical properties of four kinds of CD dyes and the photoelectric properties of the corresponding DSSCs were discussed by means of theoretical and experimental research, and the performance differences of this kind of Guang Min dyes were explained microscopically at the atomic level. The photoelectric conversion efficiency of battery devices based on CD-4,CD-5 is 1.89% and 0.61%, respectively. Furthermore, the CD-7,CD-8 prepared by introducing triphenylamine group into CD-4,CD-5 structure has more efficient photoelectric performance, and the photoelectric conversion efficiency of the battery is 4.11% and 1.51%, respectively. The results show that the improvement of the photoelectric properties of the dye is due to the enhancement of the light capture ability and steric hindrance of the photosensitive dye by the introduction of triphenylamine group. 3. Based on the prepared imidazole Guang Min dye CD-6, THF,DMF was selected as solvent to study the effect of solvent effect on the interface of dye / TiO2 photoanode and the photoelectric properties of DSSCs. The photoelectric conversion efficiency of the battery prepared with THF,DMF as sensitized solvent was 1.53% and 0.83%, respectively. The experimental results show that the absorption range of CD-6 sensitized TiO2 thin films is wider and the adsorption density of dye molecules is higher in THF. Finally, better optoelectronic properties are obtained. The effect of THF,DMF on the adsorption morphology of CD-6 on TiO2 surface was simulated by DFT theory, and the performance difference of the battery was explained at the atomic level.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM914.4

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