【作者】 裴娟；

【导师】 陈军；

【作者基本信息】 南开大学 ， 材料物理与化学， 2009， 博士

【摘要】 染料敏化太阳能电池（Dye-sensitized Solar Cells,DSCs）是一种低成本、高效率和环保的太阳能电池,自上世纪90年代以来便受到各国研究者的高度重视,已展现出十分诱人的应用前景。在染料敏化太阳能电池体系中,最核心的部分是吸附了单层光敏染料的纳米多孔半导体电极。光敏染料起着吸收太阳光并将激发态电子注入到纳米半导体导带的作用,是DSCs获得高光电转换效率和长寿命的决定因素之一。在已报道的染料敏化剂中,含贵金属的钌基敏化剂性能最好,但其成本较高。而不含贵金属的纯有机染料敏化剂具有结构多样、易于设计、成本低廉和摩尔消光系数高等优点。所以,设计合成用于替代钌基染料的纯有机染料敏化剂已经成为一项非常重要的工作。基于此,本论文主要研究高效、低成本有机染料敏化剂的设计与合成。三苯胺（Triphenylamine,TPA）及其衍生物是一类性能优良的光电材料,本论文即是选用三苯胺为基本骨架,通过简单的有机反应,设计和合成一系列三苯胺类有机敏化剂。系统研究了染料的光学、电化学性质以及在DSCs中应用,为高效、低成本的有机敏化剂的设计与合成提供理论依据。主要开展了如下几方面研究工作:1、以三苯胺（TPA）作为基本骨架,设计合成了六种具有D-π-A（electrondonor-πconjugation-electron acceptor）分子结构的新型三苯胺基染料,在此过程中还得到7种有用的反应中间体,并对这些化合物进行核磁、质谱的表征。2、研究了三苯胺基染料在溶液中以及在TiO₂膜电极上的光学性质,并分析了结构对染料光学性质的影响;所合成的三苯胺基染料都具有较高的摩尔消光系数,吸附了染料的TiO₂膜电极具有较好的光捕获能力。3、研究了染料在溶液中的电化学性质,得到了它们的氧化电位,并分析了结构对染料电化学性质的影响。结果表明,所设计合成染料的基态氧化电位和激发态氧化电位完全满足染料敏化电池中电子转移的要求。4、在B3LYP/6-31+G（d）（Becke three parameters hybrid functional withLee-Yang-Perdew correlation functionals）水平下对三苯胺基染料分子进行密度泛函（Density Functional Theory,DFT）计算,染料分子前线轨道布居分析表明染料分子在光激发后发生有效的分子内电子转移。计算结果证明了三苯胺基染料分子结构设计的合理性。5、研究了TiO₂膜的染料敏化时所用溶剂对电池性能产生的影响,结果表明,二氯甲烷（DCM）溶液敏化的膜电极,用于DSCs的测试,均表现出较好的光电性能。6、通过入射单色光光电转换效率（IPCE）以及电流-电压曲线（I-V曲线）的测试,系统表征了三苯胺基染料敏化的DSCs的光电转换性能,揭示了影响电池性能参数差异的因素。各个因素综合起来,TC16染料敏化的太阳能电池由于其高的光电流和较高的电压,而获得了最高的光电转换效率5.70%。7、考察了三苯胺基染料敏化DSCs光电性能的部分影响因素,包括电解液中Li⁺浓度、电解质添加剂、辐照度以及染料共敏化作用等。结果表明,Li⁺浓度的增大,某种程度上提高了TI-染料敏化电池的性能;硫氰酸胍（GT）的适量加入能提高电池的总体光电转换性能;电池在低辐照度下可以表现出更好的光电转换效率;染料的共敏化作用可以提高电池的电流,改善电池的性能。8、测试了三苯胺类染料的热稳定性,结果表明所合成的染料都具有较高的热稳定性。在日光下测试了基于染料TC16封装的电池的稳定性。结果表明,电池在氧化还原电解质存在的条件下没有明显的染料降解现象,并且能够保持较好的稳定性。更多还原

【Abstract】 Dye-sensitized solar cells（DSCs）,which have been emerged as cheap, high-efficiency and environmental friendly solar cells,have attracted significant attention since 1990s.The heart of DSCs system is a mesoporous oxide layer composed of nanometer-sized particle anchored by a monolayer of the charge transfer dye.Sunlight is harvested by a dye sensitizer,and then photo-excitation of the dye results in the injection of electrons into the conduction band of the oxide.Dye is one of the most important parts for DSCs to ontain high efficiency and long lifetime.Up to now,the noble-metal ruthenium polypyridyl dyes have proved to be the best dyes in DSCs,but the cost is relatively high.Metal-free organic sensitizers have been developed due to their advantages such as diversity of molecule structures, simple synthesis,high molar extinction coefficients as well as their low cost. Therefore,design and synthesis of organic dyes with high efficiency to replace Ru-based dyes have become an important work.Based on this,our work focuses on the engineering of the metal-free organic dyes.Triphenylamine（TPA） and their derivatives are excellent optical materials,and TPA is chosen as the basic framework for the design and synthesis of a series of TPA-based dyes.Photophysical and electrochemical properties of these dyes as well as their applications in DSCs were investigated.The main contents of this work are listed as follows:1.Six TPA-based orgnic dyes,which contain the typical electron donor-πconjugation-electron acceptor（D-π-A） structure,were designed and synthesized. Furthermore,seven other organic intermediates were obtained in the experiments. The structures of these componds were characterized by Nuclear Magnetic Resonance Spectrum（NMR） and Mass Spectrum（MS）.2.Photophysical properties of the as-prepared dyes in solution and adsorbed on TiO₂ film were investigated.The results show that the as-synthesized dyes have relatively high molar extinction coefficients,and the dye-coated TiO₂ films can capture light efficiently. 3.Electrochemical properties of the dyes in solution were investigated.The results show that the position of the ground-state oxidation potential and the excited-state oxidation potential are suitable for electrons transfer in the DSCs.The influence of molecular structures on the electrochemical properties was also discussed.4.Density functional theory（DFT） calculations were performed at B3LYP/6-31+G（d） level for TPA-based dyes.The populations of the frontier molecular orbitals in dyes’ molecular indicated that efficient intramolecular charge transfer occurred.The calculated results validate the rationality of molecular structure design for TPA-based organic dyes.5.Effects on DSCs performance by dye bath solvents were investigated,and dichloromethane（DCM） is chosen for sensitizers’ comparison.6.The Incident Photon-to-Ccurrent Conversion Efficiency（IPCE）and Current-Voltage（I-V） curves of the DSCs based on the as-prepared dyes were measured.The relationship between dye structures and photovoltaic performance of the DSCs were studied.The DSCs based on TC16 showed higher short current density (J_sc) and open-circuit voltage(V_oc),thus the best performance with the conversion efficiency of 5.70%was obtained.7.The factors such as the concentration of Li⁺,the additives,the light irradiation, and co-sensitization of dyes,which can affect the performance of the DSCs,were discussed.The results show that increasing Li⁺ could enhance the performance of TI-based cells.The addition of guanidinium thiocyanate（GT）,the low light irradiation and co-sensitization of dyes improve the conversion efficiency of the DSCs.8.The thermal stabilities of the TPA-based dyes were investigated.The results show that the as-synthesized dyes have good thermal stability.The long-term stability of a sealed DSC based on TC16 stored in sunlight was investigated.No sign of dye degradation was observed during the test,and the efficiency is steady-going on the whole.更多还原