【作者】 刘秀军；

【导师】 冯亚青；

【作者基本信息】 天津大学 ， 应用化学， 2013， 博士

【摘要】 本论文通过三条途径来提高卟啉染料在长波方向的吸光能力，并将其应用于染料敏化太阳能电池的研究。一是通过破坏卟啉环的平面性来增强长波方向的吸收；二是将Chlorin染料与氟硼二吡咯染料进行共敏化，通过两种染料的吸收光谱互补来提高染料体系在长波方向的吸收；三是构建双卟啉分子来提高化合物在长波方向的吸收。通过A3B型卟啉P0与2,6-二氯苯腈氧化物或2,4,6-三甲基苯腈氧化物的1,3-偶极环加成反应，合成出长波区域吸收增强的二氢卟吩(Chlorin)中间体，通过对中间体进行金属化及酯基的水解反应，分别得到2,6-二氯苯基取代的四种人工Chlorin型敏化染料ChD1a-4a和2,4,6-三甲基苯基取代的四种人工Chlorin型敏化染料ChD1b-4b，并利用1H-NMR、质谱、UV-Vis、荧光、循环伏安、TD-DFT计算、I-V曲线和IPCE谱分别对其结构、光化学、氧化还原及光伏性能进行了表征和理论研究。结果表明，Chlorin染料的光伏性能的高低取决于其吸附到TiO2膜上后紫外的Q带吸收强弱，Q带吸收强的染料敏化剂会表现出高的光电转换效率。另外，Chlorin敏化染料的光电性能与其立体结构存在着一定的依赖关系。对于位阻基团较小的2,6-二氯苯基取代的四种Chlorin型敏化染料ChD1a-4a，当位阻基团与羧基呈线性关系时存在聚积，造成效率下降，当位阻基团与羧基呈现垂直关系且吸附在TiO2膜上后Q带的吸收越强的染料，其光电转换效率越高；对于位阻基团较大的2,4,6-三甲基苯基取代的四种Chlorin型敏化染料ChD1b-4b，较大的位阻基团会防止分子聚积的形成，因此当位阻基团与羧基呈现对位的线性关系且吸附在TiO2膜上以后Q带的吸收越强的染料，其光电转换效率越高。以2,4-二甲基吡咯为原料，与对甲氧羰基苯甲醛缩合、氧化以及与BF3OEt2的配位反应，合成了氟硼化合物骨架，经与供电型芳醛Knoevenagel缩合反应和酯基的水解反应，制备出了在长波区域有强烈吸收的四种氟硼敏化染料BodD1-4，并通过1H-NMR和质谱对其结构进行了鉴定。以ChD1a与双边缩合的氟硼染料BodD2共敏化体系为依托，通过UV-Vis、吸附量测试、I-V曲线和IPCE谱对不同配比下的共敏化体系进行了研究，确定出两类染料共敏化的最佳配比为ChD1a: BodD2=8:1。在优化比例条件下，比较了ChD1a与单边缩合的氟硼染料BodD1以及ChD1a与双边缩合的氟硼染料BodD2两种共敏化体系的效果，发现单边缩合的氟硼染料与ChD1a的共敏化性能优于双边缩合的氟硼染料。这可能是由于双边缩合产物的刚性基团在一定程度上促进了分子的聚积，影响了整体的光电转化效率。用对甲基二吡咯烷和对甲氧羰基苯甲醛为原料，采用[2+2]法合成卟啉化合物P1和P2，将这两种卟啉分别还原、氧化再与金属膦盐进行Wittig反应得到了四种双卟啉分子DP1-4(其中DP1和DP3中位含一酯基，DP2和DP4中位含一醛基)。将含酯基的双卟啉分子DP1和DP3分别水解得到两个含羧基的双卟啉染料分子DPD1和DPD2，并通过1H-NMR和质谱对其结构进行了表征。然后，将两种双卟啉染料分子DPD1-2与其相应的两种单体染料分子MPD1-2进行了光学性能、电化学性能以及光电转换性能的对比研究。通过对荧光光谱的分析发现，在双卟啉分子内存在着由锌卟啉向自由碱卟啉的能量/电子转移。该结果表明，在双卟啉体系中的锌卟啉向TiO2进行电子转移过程是以自由碱卟啉为“中转站”并通过两步电子转移完成的。这在一定程度上减少了电子回传，提高了电子注入效率。并且交流阻抗谱表明，由于双卟啉分子结构较大，降低了光生电子与电解质中I3-的结合，所以暗态电阻增加，暗电流降低。通过对比四种染料分子的光伏性能得出，DPD2的转化效率比其两种单体染料MPD1和MPD2的效率都高，然而DPD1由于溶解度较差，在光阳极上的吸附不好，导致其光电转换效率偏低。更多还原

【Abstract】 In this paper, three strategies have been employed to improve the longwavelength absorption of porphyrin-based sensitizer systems in DSSC, i.e. reductionof the porphyrin to dihydroporphyrin, co-sensitized system between Chlorin-typesensitizers and BODIPY sensitizers, and construction of bis-porphyrin system.Chlorin-type framework with long wavelength absorption has been prepared bythe1,3-dipolar cycloaddition between A3B-porphyrin P0and nitrile oxides(2,6-dichlorophenyl nitrile oxide and2,4,6-trimethylphenyl nitrile oxide). Then afterthe metallization of the monoadducts by Zn2+and the following hydrolysis ofCOOMe group, Chorin-type sensitizers ChD1a-4a with2,6-dichlorophenyl group andChD1b-4b with2,4,6-trimethylphenyl group were obtained and characterized by1H-NMR, MS, UV-Vis, fluorescence, cyclic voltammetry, I-V and IPCE spectra, aswell as the TD-DFT calculation. By analysis of the above results, it was found that thephotovoltaic performance increased with growing absorption intensity of Q band onTiO2film. This result indicated the contribution of intrinsic enhanced absorptionproperties of chlorins in Q-band regions on the improvement of the overallphotovoltaic performance in DSSCs. On the other hand, their capability of solarenergy conversion also exhibited close relationship with steric structures of thesensitizers. For ChD1a-4a, the lower steric hindrance group would aggregate in thesolution when the dichlorophenyl group locate at10-position of Chlorin framework.Thus the orientation of steric hindrance group to the5-or15-position (the anchorgroup is at20-position) gave higher solar energy-to-electricity conversion efficiency.By contrast, ChD1b-4b with the higher steric hindrance group would preventaggregation, and the orientation of steric hindrance group to the10-position (theanchor group is at20-position) afforded higher solar energy-to-electricity conversionefficiency.BODIPY Bod0has been synthesized by using2,4-dimethylpyrrole andmethyl-4-formylbenzoate as the starting materials via condensation-,oxidation-reaction and the following coordination reaction with BF3OEt2.Subsequently, BODIPY sensitizers BodD1-4with strong absorption in longwavelength area were obtained by the Knoevenagel reaction between the Bod0and electron-rich aromatic aldehyde (e.g.4-(N,N-diphenyl)aminobenzene aldehyde,4-(N,N-dimethyl)aminobenzene aldehyde) followed by hydrolysis of COOMe group,and their structures have been characterized by1H-NMR and MS spectra. On the basisof co-sensitization of ChD1a and BodD2, the optimized molar ratio between ChD1a:BodD2was found to be8:1by comparing the spectra of UV-Vis in solution, UV-Vison TiO2films, surface coverage, I-V and IPCE in different molar ratios. According tothe optimal molar ratio, the photovoltaic performance of two co-sensitization systemChD1a/BodD1and ChD1a/BodD2have been evaluated. The system ofChD1a/BodD1gave better photo to electricity efficiency. This could be due to thetwo aromatic group in BodD2would undergo π-π stacking in gaining of aggregationwhich will decrease the total photo to electricity efficiency.Porphyrin intermediates P1and P2have been prepared via [2+2] method with4-methyldipyrromethane and methyl-4-formylbenzoate as the starting matrials. Aftera serials of reaction, i.e. reduction, oxidation and Wittig reaction, four porphyrindimers were obtained, where two of them contain COOMe group at meso-postion offree base porphyrin moiety and the other two contain CHO group at meso-postion offree base porphyrin moiety. Finally, two bisporphyrin sensitizers DPD1-2wereprepared by hydrolysis of the COOMe group and characterized by1H-NMR and MSspectra. Furthermore, their optical properties, chemical properties and photovoltaicperformance have been measured to compare with those of the monomers MPD1-2.In the fluorescence emission spectra of DPD1-2, the fluorescence intensity of Zincporphyrin moiety decreased and the intensity of free base porphyrin increased. Thisresult indicated that the electron/energy transfer from Zinc porphyrin unit to free baseporphyrin unit in the presence of light and free base porphyrin unit could act as a“electron-hub” between the electron from Zinc porphyrin to TiO2, which wouldprevent the electron back and increase the injection efficiency to TiO2. Moreover, inthe EIS measurement, the large moleculars of bisporphyrin decreased the combinationbetween photoelectron and I3-, and so the resistance of bisporphyrins in dark increasedwhich demonstrated the decrease of dark current. By analysis the photovoltaicperformance of the four sensitizers, DPD2gave the best result among them. In thecase of DPD1, its poor solubility lead to the lower adsorption on TiO2film, so itdidn t give better photo electricity conversion efficiency.更多还原