物理化学学报 >> 2012, Vol. 28 >> Issue (01): 78-84.doi: 10.3866/PKU.WHXB20122878

理论与计算化学 上一篇    下一篇

有机染料D-SS和D-ST用于染料敏化太阳能电池光敏剂的比较

詹卫伸, 潘石, 王乔, 李宏, 张毅   

  1. 大连理工大学物理与光电工程学院, 近场光学与纳米技术研究所, 辽宁大连 116024
  • 收稿日期:2011-06-10 修回日期:2011-11-07 发布日期:2011-12-29
  • 通讯作者: 潘石 E-mail:span@dlut.edu.cn

Comparison of D-SS and D-ST Dyes as Photo Sensitizers in Dye-Sensitized Solar Cells

ZHAN Wei-Shen, PAN Shi, WANG Qiao, LI Hong, ZHANG Yi   

  1. Institute of Near-Field Optics and Nanotechnology, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, Liaoning Province, P. R. China
  • Received:2011-06-10 Revised:2011-11-07 Published:2011-12-29
  • Contact: PAN Shi E-mail:span@dlut.edu.cn

摘要: 为了揭示D-SS 和D-ST 分子敏化的染料敏化太阳能电池(DSSCs)的物理机制, 采用密度泛函理论(DFT)、含时密度泛函理论(TDDFT)和自然键轨道(NBO)分析, 模拟计算染料D-SS和D-ST 分子的结构、紫外-可见吸收光谱和能级结构. D-SS的紫外-可见吸收光谱相比于D-ST的有明显的红移, 而且D-SS分子的摩尔吸光系数也高于D-ST分子的. D-SS分子本应该比D-ST分子拥有更高的俘获太阳辐射光子的能力, 但由于D-SS分子的最高占据分子轨道(HOMO)能级位置比氧化还原电解质(I-/I3-)的氧化还原能级高, 处于光激发态的D-SS分子向TiO2电极注入电子而被氧化后, 不能顺利地从电解质中得到电子而还原, 使得D-SS分子俘获光子的能力不能充分发挥, 从而严重地降低了由其敏化的DSSCs的光电性能和光电能量转换效率. 揭示了D-SS敏化的DSSCs的光电性能, 特别是光电能量转换效率比D-ST敏化的DSSCs的低的原因. 染料敏化剂分子的HOMO能级的位置对于DSSCs来说也是很重要的, 用于DSSCs的有机敏化剂分子的HOMO能级的位置必须低于氧化还原电解质的氧化还原能级.

关键词: 密度泛函理论, 含时密度泛函理论, 染料敏化太阳能电池, 分子模拟, 电子结构, 吸收光谱, 能级结构

Abstract: The molecular structures, UV-Vis absorption spectra, and energy level structures of the dyes D-SS and D-ST were simulated using density functional theory, time-dependent density functional theory (TDDFT), and natural bond orbital analysis, which provided the physical mechanisms of dye-sensitized solar cells (DSSCs) containing D-ST and D-SS. The UV-Vis absorption spectrum of D-SS showed a significant red shift compared with that of D-ST and the molar absorption coefficient of D-SS was higher than that of D-ST. D-SS molecules should have a higher solar radiation photon-harvesting ability than D-ST molecules, but the energy level of the highest occupied molecular orbital (HOMO) of D-SS was higher than the redox energy level of the electrolyte (I-/I3-). As a result, an optically excited D-SS molecule cannot be successfully recovered by accepting an electron from the electrolyte after being oxidized by injecting an electron towards the TiO2 electrode. This limits the photon harvesting ability of D-SS molecules, and thereby significantly decreases the photovoltaic properties and energy conversion efficiency of DSSCs containing D-SS. This allows the photovoltaic properties of DSSCs containing D-SS to be understood, especially why its photovoltaic energy conversion efficiency is lower than that of DSSCs containing D-ST. The position of the HOMO energy level of dye-sensitized molecules is very important for the operation of DSSCs, and that of the organic sensitizer molecules used in DSSCs must be lower than the redox energy level of the electrolyte.

Key words: Density functional theory, Time-dependent density functional theory, Dye-sensitized solar cells, Molecular simulation, Electronic structure, Absorption spectrum, Energy level

MSC2000: 

  • O641