染料敏化太阳能电池聚合物凝胶电解质的电荷传输及离子络合行为的NMR研究

In the field of dye-sensitized solar cells polymer gel electrolyte, cells' performances closely relate to polymer structure and electrolyte composition. So far, the key problems, ion complexation and charge transport (ion diffusion), still need further investigation. .The effect of ion complexation and charge transport can be obtained by 1H, 13C, 7Li, 23Na NMR methods..Our group propose to prepare a serial electrolytes of poly(acrylate-acrylic acid)/poly(ethylene glycol)/iodized salt/iodine gel electrolyte. DSSCs based on these polymer gel electrolyte are fabricated. The effects of various salts (NaI、KI) and solvent on ion complexation, diffusion as well as macromolecular chain conformation are studied..Meanwhile, we synthesis poly(vinyl imidazole/acrylate)/poly(ethylene glycol) /iodized salt/iodine gel electrolyte and poly(vinyl imidazole/acrylate)/ poly(ethylene glycol) /TiO2 /iodized salt/iodine gel electrolytes. The influences of imidazole rings and TiO2 in the electrolytes on the diffusion and complexation of iodine ion are studied. .The contents of acrylic acid and salts produce an effect on the complexation between metal ion and oxygen of the solvent. Diffusion of solvent and metal ions as well as macromolecular chain conformation are also affected by various acid and salt concentrations. These results can be obtained by 1H, 13C, 7Li, 23Na NMR methods. Our groups pay more attention on complexation. .IR, TGA, DSC and SEM methods are used to characterize the effects of intermolecular hydrogen bonding and complexation on the copolymer's thermostability as well as microstructure. Electrolyte conductivity and photovoltaic prepormances are deteced. .Combining these parameters with the cells' macroscopic properties , we can carry comprehensive analysis. The relationships of electrolyte molecular structure, ion complexation, diffusion coefficient, electrical conductivity and cell performance are established. The results of this research can help design polymer gel electrolytes. .Consequently, DSSCs with excellent performances can be fabricated.

在染料敏化太阳能电池聚合物凝胶电解质领域,凝胶电解质由于寿命长不易渗漏而受到关注，其作用为传输氧化/还原电对，电荷传输(离子扩散)及离子络合行为会影响氧化/还原对的传导，所以该关键问题有待深入研究。.因此，拟研究含羧基的聚(丙烯酸酯-丙烯酸)/聚乙二醇/碘盐/碘凝胶电解质、和含咪唑环的聚(乙烯基咪唑-丙烯酸酯)/PEG/碘盐/碘或加入TiO2的凝胶电解质，通过1H,13C,7Li,23Na 核磁共振NMR方法研究羧基、咪唑、碘盐含量、碘盐种类和溶剂极性对离子络合(羧基与金属,咪唑与I-)、离子扩散、分子间氢键、大分子链构象等的影响，并重点关注离子络合和扩散作用。研究分子间氢键和离子络合对耐热性和微观结构的影响；进一步分析电解质组分的络合和扩散作用对电解质电导率及电池宏观性能的相关性；建立分子结构-离子络合-离子扩散-电导率和电池性能的关系；最终为开发高性能电池用凝胶电解质提供理论依据。

1.1背景：在染料敏化太阳能电池DSSC聚合物凝胶电解质领域,聚合物结构、电解质组成与电池性能密切相关,离子络合、电荷传输(离子扩散)等关键问题有待深入研究。.1.2研究内容、重要结果、关键数据和科学意义.1）聚(甲基丙烯酸甲酯-丙烯酸丁酯-甲基丙烯酸)/聚乙二醇400/γ-丁内酯/I-/I3- (P(MMA-BA-MAA)/PEG400/GBL/I-/I3-)凝胶电解质：基于提高分子间氢键、降低固含量的思想，引入甲基丙烯酸。电导率3.12mS.cm-1。=3.63%（0.16cm2，AM 1.5, 100mW.cm-2），与相应液体电解质=3.83%相当。.2）脉冲梯度场磁共振方法（PFGSE-NMR）、循环伏安和效率研究P(MMA-BA-MAA)/PEG/NaI/I2/GBL分子组成-结构-性能：.PFGSE-NMR测试：MAA含量差异引起氢键强度不同影响GBL扩散，电池效率高低与大分子与小分子间氢键相关。比较NaI或KI与GBL扩散系数差异，NaI含量对离子络合和扩散影响。氢键和离子络合决定小分子在大分子骨架间的扩散。.循环伏安法研究氧化-还原对扩散：得I-和I3-扩散系数最大的凝胶电解质，再组装电池，可能成为评价凝胶电解质的方法之一。电池最优时，I3-扩散系数为6.957×10-4cm2/s最大。大分子组成改变，MAA=30%时，I-和I3-扩散系数最大；PEG400有助于I-/I3-参与氧化还原。.3）聚(1-乙烯基-3-丙基咪唑碘-甲基丙烯酸甲酯)/三甲氧基丙腈/LiI/I2 ([P(VPII-MMA)]/MPN/LiI/I2)凝胶电解质。交流阻抗(EIS)、I-V曲线、扫描电子显微镜(SEM)和外量子效率(IPCE)等联用证明VPII对电池性能影响。LiI浓度增大，电池暗电流增大；优化后效率为7.00%。.4）P(VPII-MMA)/MPN/LiI/I2凝胶电解质中分子结构-组成-微观聚集态-性能：PFGSE-NMR跟踪聚合物组成、有无LiI和I2时MPN的扩散系数，有I2时较好，扩散系数2.98×10-8cm2/s。与IR、DSC联用，探讨聚合物与MPN、LiI和I2间离子络合及偶极作用。可通过聚合物不同时得到MPN扩散系数预测最优电解质配方。建立分子结构-离子络合-离子扩散-电导率和电池性能的关系,最终为开发高性能电池用凝胶电解质提供理论依据。