新型梳状共聚物在准固态染料敏化太阳能电池中的应用及其对电子复合的影响

New Comb-Like Copolymer for Quasi-Solid Electrolyte Based Dye-Sensitized Solar Cells and Its Effects on Electron Recombination

合成了乙烯基咪唑碘盐(VImI)和聚乙二醇单甲醚甲基丙烯酸酯(PEGMA)的梳状共聚物.利用VImI/PEGMA共聚物制备了准固态聚合物电解质.通过光电流密度-电压(J-V)曲线和电导率测定以及电化学阻抗分析,探讨了基于此电解质的染料敏化太阳能电池的电荷传输与界面电子转移机制.结果表明,VImI/PEGMA共聚物可以有效抑制TiO2/电解质界面电子复合并提高TiO2导带能级,敏化电池的光伏性能并不完全取决于电解质的电导率.通过考察共聚物中VImI与PEGMA单元的摩尔比与开路电压的关系,发现共聚物对电子复合的抑制作用主要源于VImI链段.此外,开路电压衰减(OCVD)和瞬态光电流测试结果说明,共聚物能够提高TiO2薄膜的电子寿命,而且对陷阱电子能级的分布具有调节作用.当共聚物在电解质中的质量分数为50%,VImI与PEGMA的摩尔比为5.0时,准固态染料敏化太阳能电池于100mW·cm-2光强下获得了4.10%的光电转换效率.

A comb-like copolymer based on N-propylvinylimidazolium iodide(VImI)and poly(ethylene glycol)methyl ether methacrylate(PEGMA)was synthesized.The VImI/PEGMA copolymer was used to prepare quasi-solid electrolytes.The charge transport and interfacial charge transfer of the dye-sensitized solar cells(DSSCs)based on the quasi-solid electrolytes were investigated using photocurrent density-voltage(J-V)curves,ionic conductivities,and impedance spectra.It was found that the copolymer plays an active role in decreasing the electron recombination at TiO 2 /electrolyte interface and increases the conduction band edge of TiO 2.The photovoltaic characteristics of the DSSCs are therefore not determined entirely by the conductivity of the quasi-solid electrolyte.Based on the dependence of the open-circuit voltage on the VImI/PEGMA molar ratio,the decrease of recombination is primarily ascribed to the contribution of VImI segments.In addition,open-circuit voltage decay(OCVD)and photocurrent transient results indicate that the introduction of the copolymer not only extends the electron lifetime but also tunes the energy distribution of the localized electrons.When the VImI/PEGMA molar ratio reaches 5.0 and the mass fraction of copolymer in the quasi-solid electrolyte is 50%,the DSSC yields an energy conversion efficiency of 4.10%under an illumination intensity of 100 mW·cm-2.