Synthesis Of New Polypyridyl Ruthenium(Ⅱ) Sensitizers And Their Application In Dye-Sensitized Solar Cells

Because of its clean, low-cost, high photoelectric conversion efficiency and good stability, dye-sensitized solar cell (DSSC) is one of the most promising solar cells. Dye sensitizer, as an important component of DSSC, impacts on its photoelectric conversion efficiency, so the study on new dye sensitizer is a focus in this field.In this paper, 4,4'-dibenzoylamino-2,2'-bipyridine(ligand A) and 4,4'-diacetyl- amino-2,2'-bipyridine (ligand B) were synthesized using bipyridine as raw material , through oxidation, nitration, reduction, and N-acylation reaction, whose yields were 59.5% and 80.4% , respectively. The synthesized compounds were characterized by IR, 1H NMR and MS. At the same time, synthesis conditions for the each step reaction have been optimized.Using―one-pot‖synthetic procedure, dye sensitizers-cis-dithiocyanato- (4,4'-di- benzoylamino-2,2'-bipyridine)-(4,4'-dicarboxy-2,2'-bipyridine) ruthenium(Ⅱ) (Dye- A) and cis-dithiocyanato-(4,4'-diacetyl-2,2'-bipyridine)-(4,4'-dicarboxy-2,2'-bipyri- dine) ruthenium (Ⅱ) (Dye-B) were prepared by a complex reaction of 4,4'-dicarboxy- 2,2'-bipyridine, ligand A(or ligand B) and ammonium thiocyanate with RuCl3. The maximum absorption wavelength of Dye-A and Dye-B is 531nm and 518nm, and their molar extinction coefficient is 0.99×104M-1cm-1 and 0.75×104M-1cm-1 in methanol solution, respectively. The LUMO energy of Dye-A is -3.758eV, and Dye-B is -3.717Ev, both of which were higher than TiO2 conduction band energy level. The performances of the DSSC assembled with Dye-A are thatηis 2.88%, Voc is 0.663V, Isc is 6.48 mA·cm^-2 and FF is 0.670. The performances of the DSSC assembled with Dye-B are thatηis 2.63%,Voc is 0.665V, Isc is 5.76 mA·cm^-2 and FF=0.687.