染料敏化太阳能电池中敏化剂构效关系的理论探索与分子设计

发布时间：2018-06-07 20:04

本文选题：理论化学 + 染料敏化太阳能电池　；参考：《天津大学》2014年硕士论文

【摘要】：在染料敏化太阳能电池（dye-sensitized solar cell, DSSC）的研究中，敏化剂的分子结构设计对于电池的性能至关重要.论文针对课题组前期合成的多个系列卟啉分子的差异明显的光电转换效率，采取理论化学的方法包括密度泛函理论（DFT）、含时密度泛函理论（TDDFT）以及波函数分析方法探索了敏化剂分子结构对DSSC效率的影响因素。使用密度泛函理论计算了四苯基β位环合卟啉3-1~3-4分子的几何结构,对照其光电转化效率,表明卟啉类敏化剂应该具备合理的几何结构，应该保证敏化剂竖直单层吸附在光阳极表面。使用密度泛函理论与含时密度泛函理论计算了四苯基β位环合卟啉3-1~3-4分子和四苯基β位π桥卟啉4-1分子以及稠环类卟啉4-2分子的基态与激发态电子结构，表明激发态与基态之间的能级差对于敏化剂的紫外可见吸收光谱有很大的影响，能级差越小，敏化剂能够利用的太阳能辐射的范围越广；卟啉分子的最高占据轨道（HOMO）分布应在供电基团上，最低未占据轨道（LUMO）应分布在π桥与锚定基团上，这种正确合理的前线轨道分布是敏化剂能够有理想光电性能的前提条件，只有激发态敏化剂可以与二氧化钛可以建立适当的电子耦合，才可以使光生载流子顺利注入二氧化钛导带从而产生光电流。使用密度泛函理论与含时密度泛函理论计算了trans-AB卟啉5-1~5-4分子的基态偶极距和最强激发态的振子强度，对照该系列分子不同的光电转化效率，表明卟啉敏化剂与光阳极表面垂直方向的偶极距与DSSC的开路电压有正相关关系；激发跃迁态的振子强度决定的光捕获效率LHE与短路电流有着正相关关系。在实验分子理论研究的基础上设计了一系列β位异恶唑类卟啉分子6-2~6-5，用于弥补原实验分子的在前线轨道分布方面的缺陷，进行了基态、激发态计算以及多种波函数分析，确定了对原有缺陷的弥补效果，预测了光电效率。通过对现有苯乙炔基卟啉和芳胺类卟啉等已知实验分子的理论探索，建立了广泛紧缩福井函数，用来解释卟啉分子基团供电能力与光电性能的关系，结果表明，，DSSC光电转化效率与卟啉类敏化剂供电能力成正比。
[Abstract]:In the study of dye-sensitized solar cell, the molecular structure design of sensitizer is very important to the performance of the cell. This paper aims at the difference of photoelectric conversion efficiency of several series porphyrin molecules synthesized by our research group. The methods of theoretical chemistry, including density functional theory (DFT), time-dependent density functional theory (TDDFTT) and wave function analysis, were used to explore the influence factors of the molecular structure of sensitizer on DSSC efficiency. The geometric structure of 尾-cyclized porphyrin 3-1 3-4 molecule, Compared with its photoelectric conversion efficiency, porphyrin sensitizer should have reasonable geometric structure. The adsorption of sensitizer vertical monolayer on the surface of photoanode should be ensured. Using density functional theory and time-dependent density functional theory, the molecules of tetraphenyl 尾 cyclized porphyrin 3-1, tetraphenyl 尾-蟺-bridged porphyrin 4-1 and dense rings have been calculated by means of density functional theory and time-dependent density functional theory. The ground and excited electronic structures of porphyrin 4-2 molecules, The results show that the energy level difference between the excited state and the ground state has a great influence on the UV-Vis absorption spectrum of the sensitizer. The smaller the energy level difference, the wider the range of solar radiation can be utilized by the sensitizer. The highest occupied orbital (HOMOO) distribution of porphyrin molecules should be on the power supply group, and the lowest unoccupied orbit LUMO-distribution should be on 蟺 bridge and anchoring groups. This correct and reasonable front-line orbital distribution is the precondition for the sensitizer to have the ideal optoelectronic properties. Only the excited state sensitizer can establish an appropriate electronic coupling with titanium dioxide, Only the photogenerated carriers can be injected into the titanium dioxide conduction band smoothly to produce photocurrent. The ground state dipole distance and the oscillator intensity of the strongest excited state of trans-AB porphyrin 5-1c5-4 have been calculated by using density functional theory and time-dependent density functional theory. Compared with the different photoelectric conversion efficiency of this series of molecules, it is shown that the dipole distance between porphyrin sensitizer and the surface of photoanode has a positive correlation with the open circuit voltage of DSSC. There is a positive correlation between the optical capture efficiency (LHE) and the short-circuit current determined by the intensity of the vibrator in the excited transition state. Based on the experimental molecular theory, a series of 尾 -isooxazole porphyrin molecules 6-2C6-5 have been designed to compensate for the original experimental scores. The defects of the subs in the distribution of the frontier orbits, The ground state, excited state calculation and various wave function analysis are carried out to determine the effect of compensating the original defect and to predict the photoelectric efficiency. Through the theoretical exploration of known experimental molecules such as phenylacetylporphyrin and aromatic amine porphyrin, The extensive contraction Fukui function was established to explain the relationship between the power supply ability of porphyrin molecule group and the photoelectric performance. The results show that the photoconversion efficiency of DSSC is proportional to the power supply ability of porphyrin sensitizers.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM914.4

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