Rational Molecular Engineering of Indoline-Based D-A-π-A Organic Sensitizers for Long-Wavelength-Responsive Dye-Sensitized Solar Cells.
Rational Molecular Engineering of Indoline-Based D-A-π-A Organic Sensitizers for Long-Wavelength-Responsive Dye-Sensitized Solar Cells.
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DOI：
10.1021/acsami.5b08888
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发表时间：
2015-11
影响因子：
9.5
通讯作者：
Weiwei Zhang;Yongzhen Wu;Haibo Zhu;Qipeng Chai;Jingchuan Liu;Hui Li;Xiongrong Song;Weihong Zhu-Weihong-Z
中科院分区：
文献类型：
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作者：
Weiwei Zhang;Yongzhen Wu;Haibo Zhu;Qipeng Chai;Jingchuan Liu;Hui Li;Xiongrong Song;Weihong Zhu-Weihong-Z
吲哚类D-A-π-A有机增敏剂有望成为高效、长期稳定的染料敏化太阳能电池(DSC)的候选材料。为了进一步拓宽已知吲哚染料WS-2的光谱响应范围，我们通过增强给电子体和扩展π桥来合理地修饰分子结构，合成了两种新型吲哚类D-A-π-A有机增感剂WS-92和WS-95。通过用更富电子的咔唑单元取代WS-2的吲哚给电子体上的4-甲基苯基，染料WS-92的分子内电荷转移(ICT)吸收带从550 nm(WS-2)轻微红移到554 nm(WS-92)。相比之下，在染料WS-95中引入更大的环戊二硫吩环戊二烯单元的π桥，不仅使吸收带显著变色至574 nm，而且大大提高了摩尔消光系数(ε)，从而显著改善了染料的捕光能力。在标准的全球AM 1.5太阳光条件下，评价了两种有机染料在不含任何共吸附剂或共增敏剂的情况下，基于碘化物/三碘化合物电解液的光伏性能。基于WS-95的DSC具有更好的器件性能，功率转换效率(η)为7.69%。在WS-95的染浴中添加辅助吸附剂并没有改善光伏性能，这表明它的染料聚集可以忽略不计，这可以通过在CPDT单元上接枝的二辛基链来合理化。WS-95与短吸收波长染料S2的共增感提高了离子交换效率，使η提高到9.18%。我们的结果表明，在拓宽吲哚类D-A-π-A有机增敏剂的光谱响应方面，扩展-间隔基比增加给电子体更为合理。
Indoline-based D-A-π-A organic sensitizers are promising candidates for highly efficient and long-term stable dye-sensitized solar cells (DSSCs). In order to further broaden the spectral response of the known indoline dye WS-2, we rationally engineer the molecular structure through enhancing the electron donor and extending the π-bridge, resulting in two novel indoline-based D-A-π-A organic sensitizers WS-92 and WS-95. By replacing the 4-methylphenyl group on the indoline donor of WS-2 with a more electron-rich carbazole unit, the intramolecular charge transfer (ICT) absorption band of dye WS-92 is slightly red-shifted from 550 nm (WS-2) to 554 nm (WS-92). In comparison, the incorporation of a larger π-bridge of cyclopentadithiophene (CPDT) unit in dye WS-95 not only greatly bathochromatically tunes the absorption band to 574 nm but also largely enhances the molar extinction coefficients (ε), thus dramatically improving the light-harvesting capability. Under the standard global AM 1.5 solar light condition, the photovoltaic performances of both organic dyes have been evaluated in DSSCs on the basis of the iodide/triiodide electrolyte without any coadsorbent or cosensitizer. The DSSCs based on WS-95 display better device performance with power conversion efficiency (η) of 7.69%. The additional coadsorbent in the dye bath of WS-95 does not improve the photovoltaic performance, indicative of its negligible dye aggregation, which can be rationalized by the grafted dioctyl chains on the CPDT unit. The cosensitization of WS-95 with a short absorption wavelength dye S2 enhances the IPCE and improves the η to 9.18%. Our results indicate that extending the π-spacer is more rational than enhancing the electron donor in terms of broadening the spectral response of indoline-based D-A-π-A organic sensitizers.