Li Minjie, Kou Li, Diao Ling, Zhang Qing, Li Zhonggao, Wu Qiang, Lu Wencong, Pan Dengyu
†Department of Chemistry, College of Science and ‡Institute of Nanochemistry and Nanobiology, Shanghai University, Shanghai 200444, PR China.
J Phys Chem A. 2015 Apr 2;119(13):3299-309. doi: 10.1021/acs.jpca.5b00798. Epub 2015 Mar 18.
The electronic structures and absorption spectra for a series of acene-based organic dyes and the adsorption energy and optical properties for these dyes adsorbed on (TiO2)38 have been investigated using density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. The effects of acene units and different substitution positions of electron donors on the optoelectronic properties of the acene-modified dyes are demonstrated. The photophysical properties of tetracene- and pentacene-based dyes are found to be tuned by changing the size of acene and the substitution position of the donor. The donor sites have a significant influence on the absorption wavelength mainly because of different molecular orbital (MO) contributions of the highest occupied molecular orbital (HOMO) on the bridging acene units, and the increasing MO contribution would lead to the red shift in the absorption spectra. Meanwhile, the donor is located close to the center of the π-conjugated bridge, and the absorption spectra are extended. The adsorption energy and optical properties of tetracene- and pentacene-based dyes adsorbed on (TiO2)38 suggest that acene-bridged dyes could be adsorbed on the TiO2 surface and inject electrons into semiconductors effectively. Then the results obtained from the hexacene-based dyes confirm the conclusions proposed from the tetracene- and pentence-based dyes. This study will provide a useful reference to the future design and optimization of acene dyes for dye-sensitized solar cell applications.
采用密度泛函理论（DFT）和含时密度泛函理论（TDDFT）方法，研究了一系列并苯类有机染料的电子结构和吸收光谱，以及这些染料吸附在(TiO2)38上的吸附能和光学性质。证明了并苯单元和电子给体不同取代位置对并苯改性染料光电性质的影响。发现通过改变并苯的尺寸和给体的取代位置，可以调节基于并四苯和并五苯的染料的光物理性质。给体位点对吸收波长有显著影响，这主要是由于桥连并苯单元上最高占据分子轨道（HOMO）的不同分子轨道（MO）贡献，MO贡献的增加会导致吸收光谱发生红移。同时，给体位于π共轭桥的中心附近时，吸收光谱会展宽。基于并四苯和并五苯的染料吸附在(TiO2)38上的吸附能和光学性质表明，并苯桥连染料可以吸附在TiO2表面并有效地将电子注入半导体。然后，基于并六苯的染料所得到的结果证实了基于并四苯和并五苯的染料所提出的结论。该研究将为未来用于染料敏化太阳能电池应用的并苯染料的设计和优化提供有用的参考。
