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高摩尔消光钌染料敏化剂的合成及应用

Synthesis and Application of Ruthenium Sensitizers with High Molar Extinction Coefficient

【作者】 王媛

【导师】 景晓燕;

【作者基本信息】 哈尔滨工程大学 , 应用化学, 2008, 硕士

【摘要】 本论文通过引入噻吩、呋喃、3,4-乙烯二氧噻吩(EDOT)、并二噻吩和并三噻吩基团,延伸天线配体的π系统,合成5种多吡啶金属钌配合物染料,即C系列钌染料。提高了摩尔消光系数,适当增强了染料在介孔二氧化钛膜上的光吸收率,缩短了光吸收长度,提高了电荷收集率,制备了更加高效的染料敏化太阳能电池。利用紫外-可见分光光度法,荧光分析法,ATR-FTIR,循环伏安法,对染料的摩尔消光系数,激发光谱,与TiO2薄膜固定模式,氧化-还原电位等性能进行研究。结果表明,C101,C102,C104染料的摩尔消光系数分别为17.5×103M-1·cm-1,16.8×103 M-1·cm-1和20.5×103 M-1·cm-1。C系列钌染料基态时的氧化还原电位(vs NHE)分别为0.904 V,0.919 V,0.901 V,0.961 V和0.942 V,均比电解质中I3-/I-电子对的氧化还原电位0.535 V要高,因此为染料再生和净电荷的分离提供了充足的驱动力。另外,从红外光谱图中可以看到染料与TiO2膜的固定模式是染料羧酸基团与表面的钛离子之间通过双齿螯合作用连接固定。染料器件的效率、光电性能及光热稳定性的测试结果表明,以乙腈体系电解质制备的C101染料器件,在长期老化测试中达到了令人瞩目的效率11.0%~11.3%;基于低挥发性的3-甲氧基丙腈电解质和无挥发性的离子液体电解质的器件效率分别高于9.0%和7.4%,经过1000小时全太阳光照射,效率仍能够保持最初的95%,是迄今为止最高效稳定的染料敏化剂,建立了评价染料敏化太阳能电池性能的国际新标准。C104染料在初步的器件测试中,其电池的功率转换效率已经达到10.53%,相信经过进一步的优化会成为更加有前景的染料。此外,通过电阻抗测试,比较C101乙腈做电解质和离子液体做电解质的器件,结果表明电子扩散长度的缩短与电子扩散系数减小和电子寿命缩短有关,这也解释了两个器件光电流的差异。因此,离子液体电解质的器件需要做更多的努力来提高效率,促进实现大规模生产柔性薄膜太阳能电池。

【Abstract】 In this thesis,by introducing thiophene,furan,3,4-ethylenedioxythiophene (EDOT),thieno[3,2-b]thiophene,and dithieno[3,2-b:2’,3’-d]thiophene units in order to extend theπconjugation of spectator ligands,we have synthesized five new heteroleptic polypyridyl ruthenium complexes coded C101-C105 with high molar extinction coefficients to enhance the optical absorptivity of mesosporous titania film and charge collection yield in dye-sensitized solar cell,further,to prepare higher effective dye-sensitized solar cells.The sensitizers’ molar extinction coefficients,emission spectra,anchored modes on the surface of TiO2 film,the redox potentials were studied by using of UV-vis,spectrofluorometer,ATR-FTIR and cyclic voltammetry.The devices efficiencies,photovoltaic characterization and stability were also tested.It demonstrated that the molar extinction coefficients(ε) of the low-energy MLCT absorption bands for C101,C102 and C104 are 17.5 M-1·cm-1,16.8×103 M-1·cm-1,and 20.5×103 M-1·cm-1,respectively.The redox potentials of the ruthenium center in sensitizers determined by ultramicroelectode square-wave volammetry are 0.904 V,0.919 V,0.901 V,0.961 V and 0.942 V(vs NHE), which are all higher than that of the iodide electron donor,providing ample driving force for efficient dye regeneration,avoiding the geminate charge recombination.According to the tests of devices’ efficiencies,photovoltaic characterations and stabilities,along with an acetonitrile based electrolyte,the C101 sensitizer has already achieved a strikingly high efficiency of 11.0%~11.3%even under a preliminary testing.More importantly,based on a low volatility 3-methoxypropionitrle electrolyte and a solvent-free ionic liquid electrolyte cells having corresponding>9.0%and~7.4%efficiencies retained over 95%of their initial performances after 1,000 h full sunlight soaking at 60℃.The more striking is that with this C101 sensitizer,several new DSSC benchmarks under the air mass 1.5 global(AM 1.5G) sunlight have been reached.The preliminary tests show that for a newly developed C104 dye,the achievement of over 10.5%power conversion efficiencies is very encouraging,and we will further systematically optimize the cell parameters of different DSCs to take the full potential of this promising sensitizer with enhanced optical absorptivity.With the aid of electrical impedance measurements we further disclose that compared to the cell with an acetonitrile based electrolyte,a dye-sensitized solar cell with an ionic liquid electrolyte shows a feature of much shorter electron diffusion lengths due to the lower electron diffusion coefficients and shorter electron life times,explaining the photocurrent difference between these two type devices.This highlights the necessary efforts to further improve the efficiency of cells with ionic liquid electrolytes,facilitating the large-scale production and application of flexible thin film mesoscopic solar cells.

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