Inorganic Chemistry, Vol.54, No.16, 7742-7752, 2015
Tunable Luminescence and Application in Dye-Sensitized Solar Cells of Zn(II)/Hg(II) Complexes: Methyl Substitution-Induced Supramolecular Structures Based on (E)-N-(6-Methoxypyridin-2-ylmethylene)arylamine Derivatives
Using Schiff-base ligands (E)-N-(6-methoxypyridin-2-y1)(CH=NAr) (where Ar = C6H5, Li; 2-MeC6H4, L-2; 2,4,6Me(3)C(6)H(2), L-3), six Zn(II)/Hg(II) complexes, namely, [ZnLiC12] (Znl), [HgL1C(12)] (Hgl), [ZnL2C(12)] (Zn2), [HgL2C12] (Hg-2), [ZnL3C12] (Zn-3), and [HgL3C12] (Hg-3) have been synthesized under solvothermal conditions. The structures of six complexes have been established by X-ray single-crystal analysis and further physically characterized by EA, FT-W, NMR, and ESI-MS. The crystal structures of these complexes indicate that noncovalent interactions, such as hydrogen bonds, C-H-C1, and pi(center dot center dot center dot)pi stacking, play essential roles in constructing the resulting supramolecular structures (1D for Hg3; 2D for Zn2, Hg2; 3D for Znl, Hgl, and Zn3). Upon irradiation with UV light, the emission of complexes Znl-Zn3 and Hgl-Hg3 could be finely tuned from green (480-540 nm) in solid state to blue (402-425 nm) in acetonitrile solution. It showed that the ligand and metal cation can influence the structures and luminescence properties of complexes such as emission intensities and maximum wavelengths. Since these ligands and complexes could compensate for the absorption of N719 in the low-wavelength region of the visible spectrum and reduce charge recombination of the injected electron, the ligands L-1-L-3 and complexes Zn3/Hg3 were employed to prepare cosensitized dye-sensitized solar cells devices for investigating the influences of the electron-donating group and coordination on the DSSCs performance. Compared to DSSCs only being sensitized by N719, these prepared ligands and complexes chosen to cosensitize N719 in solar cell do enhanced its performance by 11-41%. In particular, a DSSC using L-3 as cosensitizer displays better photovoltaic performance with a short circuit current density of 18.18 mA cm(-2), corresponding to a conversion efficiency of 7.25%. It is much higher than that for DSSCs only sensitized by N719 (5.14%).