化学学报 ›› 2014, Vol. 72 ›› Issue (6): 697-703.DOI: 10.6023/A14040310 上一篇    下一篇

研究论文

吡啶基酞菁Ru配合物电子结构和光谱性质计算

张明晶a, 潘清江a, 郭元茹b, 张红星c   

  1. a. 黑龙江大学化学化工与材料学院 功能无机材料化学省部共建教育部重点实验室 哈尔滨 150080;
    b. 东北林业大学材料科学与工程学院 生物质材料科学与技术教育部重点实验室 哈尔滨 150040;
    c. 吉林大学理论化学研究所 理论化学计算国家重点实验室 长春 130023
  • 收稿日期:2014-04-22 出版日期:2014-06-14 发布日期:2014-05-14
  • 通讯作者: 潘清江,郭元茹 E-mail:panqjitc@163.com;guoyrnefu@163.com
  • 基金资助:
    项目受国家自然科学基金(No.21273063)、教育部新世纪优秀人才支持计划(No.NCET-11-0958)和黑龙江省留学回国人员科技项目择优资助.

Electronic Structures and Spectroscopy of Pyridyl Ru-phthalocyanine Photosensitizers

Zhang Mingjinga, Pan Qingjianga, Guo Yuanrub, Zhang Hongxingc   

  1. a. Key Laboratory of Functional Inorganic Material Chemistry of Education Ministry, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080;
    b. Key Laboratory of Bio-based Material Science & Technology of Education Ministry, College of Material Science and Engineering, Northeast Forestry University, Harbin 150040;
    c. State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023
  • Received:2014-04-22 Online:2014-06-14 Published:2014-05-14
  • Supported by:
    Project supported by National Natural Science Foundation of China (No.21273063), Program for New Century Excellent Talents in University (No.NCET-11-0958) and the Foundation of Heilongjiang Province for the Returned Overseas Chinese Scholars.

使用DFT和TD-DFT方法研究配合物[PcRu(RPy)(Py-COOH)](Pc为酞菁;Py为吡啶;R分别代表COOH,CN,H,Me和OMe)以及它们的单、双电子氧化衍生物的电子结构和吸收光谱,分析表明中性配合物分子要比其氧化态更适合做染料.计算配合物在350 nm处有一个较强的Soret高能吸收带,而在600 nm的Q带吸收相对较弱.这些电子光谱被指认为酞菁环内的π→π*跃迁和Ru→Py-COOH电荷转移.由于染料是通过轴向吡啶上的羧酸与半导体光阳极相联接,所以配合物的π→π*跃迁对随后的电子注入没有贡献;加之该类配合物在400~580 nm可见光区无吸收,解释了该类配合物染料敏化太阳能电池光电转换效率低的原因.

关键词: 酞菁Ru光敏染料, 单、双电子氧化态, 电子光谱, 含时密度泛函理论

It is well known that photosensitizers play a vital role in the dye-sensitized solar cells (DSSCs).Understanding of their structures and photophysical properties is necessary to enhance the photoelectric conversion efficiency of DSSCs.In this work, a series of sensitizers [PcRu(RPy)(Py-COOH)] (Pc=phthalocyanine, Py=pyridine, R=COOH, CN, H, Me and OMe) as well as their one- and two-electron oxidized derivatives have been investigated using density functional theory (DFT) and time-dependent DFT.Their structural and spectroscopic properties were addressed.Full optimization demonstrates the ruthenium center exhibits octahedral geometry with six nitrogen donors.One- and two-electron oxidation slightly shortens equatorial Ru-N bond lengths relative to neutral dyes, but lengthens their axial ones.The experimentally known RuPc-1 has been calculated to evaluate performance of various functionals, basis sets, computational models of solvent effect and solvent sorts.And the TD-BLYP/SDD/PCM/Ethanol approach was used for spectral calculation in the present work.The comparison among calculated absorption spectra reveals that the neutral complexes are more suitable for photosensitizers in dye-sensitized solar cells than their oxidized derivatives.Neutral dyes were calculated to display a strong Soret absorption peak at 350 nm and a relatively weak Q band at 600 nm.They were assigned as intra-phthalocyanine π→π* transition and Ru→Py-COOH metal-to-ligand charge transfer.As these dyes anchor to semiconductor photoanode by the carboxyl of axial pyridyl group, their π→π* transition has no contribution to the subsequent electron injection.Further association with above ruthenium dyes missing absorption between 400~580 nm in visible region elucidates why DSSCs sensitized by them have such a low overall conversion efficiency of photo to electricity.Building on the present results, it is suggested to fabricate a sensitizer like [((COOH)n-(Pc))Ru(L)2], where anchoring carboxylic acids are bonded to equatorial Pc macrocycle and strong electron-donating groups are axially introduced.With this arrangement, Ru center, donating L groups and Pc macrocycle (high-lying π occupied orbitals) all serve as electron donors, while Pc ligand (low-lying π* unfilled orbitals) and peripheral carboxylic substituents behave as electron-accepting reservoir.This in-progress work is anticipated to design dyes that improve the conversion efficiency of DSSCs.

Key words: Ru-phthalocyanine sensitizer, one- and two-electron oxidation, electronic spectrum, time-dependent density functional theory (TD-DFT)