文献类型：期刊文献

英文题名：High-conversion-efficiency organic dye-sensitized solar cells: molecular engineering on D-A-π-A featured organic indoline dyes

作者：Wu, Yongzhen[1,2];Marszalek, Magdalena[3];Zakeeruddin, Shaik M.[3];Zhang, Qiong[1,2];Tian, He[1,2];Graetzel, Michael[3];Zhu, Weihong[1,2]

机构：[1]E China Univ Sci & Technol, Shanghai Key Lab Funct Mat Chem, Key Lab Adv Mat, Shanghai 200237, Peoples R China;[2]E China Univ Sci & Technol, Inst Fine Chem, Shanghai 200237, Peoples R China;[3]Swiss Fed Inst Technol, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland

年份：2012

卷号：5

期号：8

起止页码：8261

外文期刊名：ENERGY & ENVIRONMENTAL SCIENCE

收录：;EI(收录号：20123115292770);WOS:【SCI-EXPANDED(收录号:WOS:000306571800021)】；

基金：This work was financially supported by NSFC/China, National 973 Program (2011CB808400), the Oriental Scholarship, SRFDP 200802510011, the Fundamental Research Funds for the Central Universities (WK1013002), and STCSM (10dz2220500). MG thanks National Science Foundation for the financial support. We thank Mr Pascal Comte for providing TiO2 films and Dr Carole Gratzel and Dr Robin Humphry-Baker for helpful discussions.

语种：英文

外文关键词：Conversion efficiency - Design for testability - Density functional theory - Electrolytes - Titanium dioxide - Ionic liquids - Electrochemical impedance spectroscopy - Thiophene - Cell engineering - Solar power generation

摘要：This paper reports a new D-A-pi-A organic dye WS-9, which is derived from the known dye WS-2 by incorporating an n-hexylthiophene unit into the pi-conjugation. Due to the presence of a strong electron-withdrawing benzothiadiazole unit in the pi-bridge, the specific D-A-pi-A organic dyes show more complicated electronic transition absorption bands than traditional D-pi-A dyes. The origins of the absorption bands in D-A-pi-A organic dyes are analysed by density functional theory (DFT). The calculated results in combination with the deprotonation experiments suggest that the spectral response range of D-A-pi-A organic dyes is superior to that of D-pi-A ones. When employed in dye-sensitized solar cells (DSSCs), the two dyes show a large difference in aggregation behaviour. It was found that WS-2 forms the unfavourable aggregates more easily. High performance of WS-2 strongly depends on the coadsorbent and suitable dye bath solvent. In contrast, WS-9 shows strong anti-aggregation ability, and always exhibits high performance regardless of the coadsorbent and dye bath solvent. Transient photovoltage and photocurrent decay experiments as well as electrochemical impedance spectroscopy indicate that the injected electron lifetime and charge recombination resistance are largely increased due to the introduction of a hexylthiophene unit, resulting in the high photovoltage based on WS-9. The optimized power conversion efficiency of WS-9 reaches 9.04% with high photocurrent (18.00 mA cm(-2)) and photovoltage (696 mV). The accelerating dye photo-stability was tested upon light irradiation of a dye-adsorbed TiO2 film in the absence of redox electrolyte, and a WS-9-based DSSC device with ionic liquid redox electrolyte. These results suggest that the structural engineering of organic dyes is important for highly efficient photovoltaic performance of solar cells, and our research will pave a novel way to design new efficient D-A-pi-A organic dye sensitizers.