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化学学报
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化学学报 ›› 2013, Vol. 71 ›› Issue (11): 1527-1534.DOI: 10.6023/A13080914 上一篇    下一篇

研究论文

高效金属双卟啉染料的计算设计及其敏化TiO2半导体复合体系的理论研究

朱纯a,b, 曹泽星b   

  1. a 贵州大学化学与化工学院 贵阳 550025;
    b 厦门大学化学与化工学院固体表面物理化学国家重点实验室和福建省理论与计算化学重点实验室 厦门 361005
  • 投稿日期:2013-08-30 发布日期:2013-09-27
  • 通讯作者: 曹泽星 E-mail:zxcao@xmu.edu.cn
  • 基金资助:

    项目受国家重点基础研究发展计划(973)项目(Nos. 2011CB808504, 2012CB214900)、国家自然科学基金(Nos. 21133007, 21373164)和贵州省科学基金(No.[2012]2151)资助.

Unique Metal Di-Porphyrin Dyes with Excellent Photoelectronic Properties for Solar Cells：Insight from Density Functional Calculations

Zhu Chuna,b, Cao Zexingb   

  1. a School of Chemistry and Chemical Engineering, Guizhou University, Guizhou 550025, China;
    b State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
  • Received:2013-08-30 Published:2013-09-27
  • Supported by:

    Project supported by the Ministry of Science and Technology (Grant Nos. 2011CB808504 and 2012CB214900), the National Natural Science Foundation of China (Grant Nos. 21133007, 21373164) and Science Foundation of Guizhou Province (No.[2012]2151).

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基于广泛的密度泛函理论计算, 理论上设计并表征了一类新型的金属双卟啉染料. 这些新型的卟啉染料具有很强的光捕获能力, 且其低激态表现出优良的电荷分离性质. 通过对这类染料体系的结构修饰, 如包含不同金属的共轭大环(卟啉环或咔咯环)的取代, 可以很容易地调控它们的光电子性质. 计算表明, 这类金属双卟啉染料的电子性质能很好地匹配不同的氧化还原电对, 在染料太阳能敏化电池研究中具有好的应用前景. 基于第一性原理计算, 预测了金属双卟啉染料敏化TiO2体系的电子结构性质, 讨论了可能的直接和间接电子注入机制, 其间接电子注入时间约20 fs, 电子注入过程非常快.

关键词: 染料敏化太阳能电池, 金属双卟啉染料, 电子注入机理, 密度泛函理论计算

A new type of metal di-porphyrin dyes have been designed and characterized by density functional calculations. Structural optimizations and subsequent frequency calculations for the isolated dyes were performed using the B3LYP hybrid functional in combination with the all-electron 6-31G(d) basis set. Bulk solvent effects were evaluated by using the continuum solvation model of SMD. Vertical excitation energies were computed by means of time-dependent density functional theory with CAM-B3LYP functional. The two-dimensional slab model of the most stable anatase TiO2 (101) surface was used to calculate the structural and electronic properties of dye-TiO2 system by using the plane-wave technique implemented in Vienna ab initio simulation package (VASP). The electron injection times from the dye to the semiconductor were estimated by using a model derived from the Newns-Anderson approach. Calculations show that these novel porphyrin-based sensitizers have a strong light harvesting ability and an excellent charge separation in the excited states. Their optical and charge-transfer properties can be well modulated by incorporating different metals and different conjugated macrocycles. Moreover, the more positive energy level of HOMO orbital of the metal di-porphyrin dye than the bottom of conduction band of TiO2 ensures an effective electron injection from the excited dyes to TiO2, and its energy level of LUMO orbital can nicely match various redox couples to facilitate regeneration of the oxidized dyes. Accordingly the porphyrin-based complexes are quite promising for fabrication of the high performance dye-sensitized solar cells. Based on the first-principles calculations, plausible mechanisms for direct and indirect electron injections from the adsorbed dye to TiO2 have been discussed. In the indirect process, the dye is initially promoted to the excited state with the charge separation under light excitation of relatively short wavelength region, followed by the electron transfer from the excited dye to TiO2. Such electron injection process is predicted to be very fast and the estimated electron injection times are only about 20 fs. The direct electron injection from dye to TiO2 may occur under optical excitation in relatively long wavelength region.

Key words: dye-sensitized solar cells (DSCs), unique metal di-porphyrin dyes, electron injection mechanism, density functional calculations