Rational Molecular Engineering of Indoline-Based D-A-蟺-A Organic Sensitizers for Long-Wavelength-Responsive Dye-Sensitized Solar Cells

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• 作者：Weiwei Zhang ; Yongzhen Wu ; Haibo Zhu ; Qipeng Chai ; Jingchuan Liu ; Hui Li ; Xiongrong Song ; Wei-Hong Zhu
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：December 9, 2015
• 年：2015
• 卷：7
• 期：48
• 页码：26802-26810
• 全文大小：512K
• ISSN：1944-8252

文摘

Indoline-based D-A-蟺-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 蟺-bridge, resulting in two novel indoline-based D-A-蟺-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 蟺-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 (蔚), 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 (畏) 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 畏 to 9.18%. Our results indicate that extending the 蟺-spacer is more rational than enhancing the electron donor in terms of broadening the spectral response of indoline-based D-A-蟺-A organic sensitizers.