染料敏化太阳能电池中具有不同芳基胺类给体的有机染料的理论研究
发布时间：2019-06-28 11:28
【摘要】：自从1991年Gr tzel等人报道了具有简单结构的染料敏化太阳能电池(DSSCs)的效率高达7%以来，DSSCs就引起了人们的广泛关注。与传统的硅基半导体太阳能电池相比，DSSCs具有高能量转换效率及低成本等优点。实验上以锌卟啉类染料为光敏剂的DSSCs的效率已达到12.3%。然而，由于金属的价格昂贵，因此限制了DSSCs的大规模商业化应用。近些年，基于非金属有机染料的DSSCs因其低成本、易制备、环保，同时具有较高的光电转换效率等优点而越来越受到人们的重视。光敏染料作为DSSC的重要组成部分，其结构上的微小差异会引起器件性能的显著不同。但实验上设计合成高效的染料分子仍存面临巨大挑战，近年来，，量子化学方法已成为了揭示染料分子结构与性能之间关系的可靠的研究手段。 本文主要包括两部分研究工作： 第一部分： 为了合理解释二聚噻吩类染料分子结构与性能之间的关系，采用密度泛函理论(DFT)和含时密度泛函理论(TDDFT)讨论了包括紫外-可见吸收光谱、光捕获效率、电子注入驱动力、垂直方向偶极矩和电子转移数目在内的一系列影响染料性能的理论参数．结果表明，在光捕获效率和电子注入效率差别不大的情况下，染料分子较低的染料再生效率可导致其短路电流较小;同时，在由光诱导产生的从染料分子转移到半导体的电子数目以及电子复合程度相差不大的情况下，染料分子垂直方向上较大的偶极矩则可导致其具有较高的开路电压． 第二部分： 为了揭示D-D-π-A型染料的结构和性能之间的关系，本文结合密度泛函理论（DFT）以及含时密度泛函理论（TDDFT）围绕染料分子的几何、电子结构，吸收光谱，电化学性质，电子复合程度，以及半导体导带边缘的移动进行讨论。结果表明：相比于常规经典的D-π-A型染料分子，引入额外的给体，即D-D-π-A型双给体染料，可以改变体系的共轭程度，增加染料的光吸收强度；其中吩噻嗪和二苯胺基等非平面性给体的引入可以使染料吸收光谱红移，并且显著的调节染料的基态、激发态的氧化电位；反之，咔唑刚性给体的引入则使吸收光谱蓝移，只能微调染料的基态、激发态的氧化电位。另外，额外给体的引入可以显著增加染料阳离子空穴-半导体之间的距离，从而抑制注入电子与染料阳离子的复合；在额外给体中引入杂原子可以使I2聚集在染料外侧，从而降低电解质在半导体表面的局域浓度，进而减慢注入电子与电解质之间的复合速率。尽管额外给体的引入可以引起导带移动发生变化，但是这种变化并不显著的，可以忽略。计算结果表明通过在常规经典的D-π-A型染料上引入额外的电子给体构筑D-D-π-A型染料可以有效调节染料的光学、电学以及电子复合等各方面性质，从而为高性能的染料提供更直观、清晰的思路。
[Abstract]:Since Gr tzel et al reported that the efficiency of dye-sensitized solar cell (DSSCs) with simple structure is as high as 7% in 1991, DSSCs has attracted extensive attention. Compared with the traditional silicon-based semiconductor solar cells, DSSCs has the advantages of high energy conversion efficiency and low cost. In the experiment, the efficiency of DSSCs with zinc porphyrin dye as photosensitizer has reached 12.3%. However, because of the high price of metals, the large-scale commercial application of DSSCs is limited. In recent years, DSSCs based on non-metallic organic dyes has been paid more and more attention because of its low cost, easy preparation, environmental protection and high photoelectric conversion efficiency. As an important part of DSSC, the slight difference in structure of photosensitive dye will lead to significant difference in device performance. However, the experimental design and synthesis of efficient dye molecules are still facing great challenges. In recent years, quantum chemistry method has become a reliable research method to reveal the relationship between molecular structure and properties of dyes. This paper mainly includes two parts: in order to reasonably explain the relationship between molecular structure and properties of dithiophene dyes, density functional theory (DFT) and time-dependent density functional theory (TDDFT) are used to discuss the UV-vis absorption spectrum, light capture efficiency and electron injection driving force. A series of theoretical parameters affecting dye performance, including vertical dipole moment and electron transfer number, show that the lower dye regeneration efficiency of dye molecules can lead to smaller short circuit current when there is little difference between light capture efficiency and electron injection efficiency. At the same time, when the number of electrons transferred from dye molecule to semiconductor induced by light and the degree of electron recombination are not much different, the larger dipole moment of dye molecule in vertical direction can lead to higher open circuit voltage. Part two: in order to reveal the relationship between the structure and properties of D 鈮
本文编号：2507264
[Abstract]:Since Gr tzel et al reported that the efficiency of dye-sensitized solar cell (DSSCs) with simple structure is as high as 7% in 1991, DSSCs has attracted extensive attention. Compared with the traditional silicon-based semiconductor solar cells, DSSCs has the advantages of high energy conversion efficiency and low cost. In the experiment, the efficiency of DSSCs with zinc porphyrin dye as photosensitizer has reached 12.3%. However, because of the high price of metals, the large-scale commercial application of DSSCs is limited. In recent years, DSSCs based on non-metallic organic dyes has been paid more and more attention because of its low cost, easy preparation, environmental protection and high photoelectric conversion efficiency. As an important part of DSSC, the slight difference in structure of photosensitive dye will lead to significant difference in device performance. However, the experimental design and synthesis of efficient dye molecules are still facing great challenges. In recent years, quantum chemistry method has become a reliable research method to reveal the relationship between molecular structure and properties of dyes. This paper mainly includes two parts: in order to reasonably explain the relationship between molecular structure and properties of dithiophene dyes, density functional theory (DFT) and time-dependent density functional theory (TDDFT) are used to discuss the UV-vis absorption spectrum, light capture efficiency and electron injection driving force. A series of theoretical parameters affecting dye performance, including vertical dipole moment and electron transfer number, show that the lower dye regeneration efficiency of dye molecules can lead to smaller short circuit current when there is little difference between light capture efficiency and electron injection efficiency. At the same time, when the number of electrons transferred from dye molecule to semiconductor induced by light and the degree of electron recombination are not much different, the larger dipole moment of dye molecule in vertical direction can lead to higher open circuit voltage. Part two: in order to reveal the relationship between the structure and properties of D 鈮
本文编号：2507264
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