摘要敏化剂作为染料敏化太阳能电池(DSSC)的核心组成部分，对光捕获效率和能量转换效 率有重要影响。实验设计和优化敏化剂提高电池效率，仍是一个巨大的挑战。量子化学计 算能够在分子水平下高效率的预测光谱获效率，揭示染料结构与对能量转换效率的影响， 已成为实验研究DSSC的重要补充手段。本论文以ABAB型酞菁敏化剂作为主要研究对象， 采用密度泛函理论(DFT)和含时密度泛函理论(TDDFT)方法，从理论上探讨酞菁母体结构及 不同偶极取代衍生物的结构与光谱性能之间的关系，为实验设计高性能的有机D-π-A敏化 剂提供理论指导。研究内容包括如下两部分。

首先采用DFT方法在B3LYP/6-31G*水平上比较了ABAB型酞菁衍生物的几何结构，在 此基础上用TDDFT方法计算了激发态，研究了ABAB型酞菁具有不同取代基对其电子结构 和电子吸收光谱的影响。结果表明，3,6-(3',5'-双三氟甲基/三甲基)苯基的加入，前线轨道能 级裂分导致Q带红移并出现了不同程度的裂分，Qx吸收带均红移，三氟甲基使Qy带蓝移。 这种大的取代基在可见光区谱带的调制功能可以有效提高敏化剂的光捕获效率。73223

基于以上工作，我们采用DFT方法在B3LYP/6-31G*水平上优化了不同偶极方向的v型 和p型酞菁衍生物的几何结构，并在此基础上采用TDDFT方法计算了各自的激发态，研究 了不同π桥以及这些π桥在ABAB型酞菁不同位置对其电子结构以及电子吸收光谱的影响。 计算结果表明，v型光敏染料的最大波长普遍高于p型光敏染料，vME和vMY表现尤为突出， 具有较强吸收、更宽的谱带以及较大短路电流密度。本论文工作为高效酞菁染料的实验合 成和设计提供理论指导。

毕业论文关键词： 染料敏化剂，酞菁，密度泛函，电荷差分密度，电子吸收光谱

Abstract As a core component of dye-sensitised solar cell(DSSC), sensitizers have an important effect on the lighting harvesting efficiency and the overall photoelectric conversion efficiency(PCE)。 However, it is still a great challenge for the improvement of PCE to the experimental design and optimization of sensitizers。 Quantum chemical calculations could forecast the lighting harvesting efficiency(LHE) and unclose the effect of sensitizer structure on PCE of DSSC at a molecular level。 Thus, quantum chemical calculations manifest themselves as a reliable and important avenue to promote the experimental investigation。 Herein, density functional theory (DFT) and time-dependent DFT (TDDFT) calculations were performed on ABAB type phthalocyanine-based sensitizers to shed light on the structure-property relationships for the different dipole derivatives and thus to provide theoretical guidelines for the experimental optimization and design of D-π-A type organic sensitizers。 The research contents include two parts in the following:

Firstly, the molecular geometries, electronic structures of ABAB-type Zn(II) phthalocyanine compounds were investigated using the B3LYP method within a framework of DFT。 The excitation energies of these molecules were computed by TD-DFT methods。 The calculated results  of  three  compounds  reflect  the  interpolation  of  bulky     3,6-(3′,5′-bis(trifluoromethyl

/methyl)phenyl)phthalonitrile results in a red shift of the Q band and a different splitting degree。 The specific performance can be described as the red shift of their Qx band and the blue shift of Qy band of phthalocyanine derivatives with trifluoromethyl groups。 Large substituents with adjustment function in the visible region can effectively improve the LHE of sensitizer。

Based on the above work, the molecular geometries of ABAB-type phthalocyanine derivatives with different dipole orientations including vertical and parallel positions were investigated using the B3LYP method within a framework of DFT。 The excitation energies of these molecules were computed by TD-DFT methods。 The results show that the maximum wavelength of the V type photosensitive dye is generally higher than that of the P type。 The compounds, vME and vMY have stronger absorption and maximal short circuit current density(Jsc) in the near infrared region。 The present results provide theoretical guidance for the experimental synthesis and design of high efficiency phthalocyanine dyes。