Abstract
New ruthenium (II) complexes, [Ru(DHZ)2(bpy)], [Ru(SCN)2(bpy)(DMSO)2], [Ru(SCN)2(dmbpy)(DMSO)2] and [RuCl2(salen)]-2, where bpy = 2,2'- bipyridine, DHZ = 1,5-diphenylthiocarbazone, dmbpy = 4,4'-dimethyl-2,2' bipyridine and salen = 2,2'- ethylenebis(nitrilomethylidene)diphenol were synthesized and characterized by elemental analysis, FTIR, UV-Vis spectroscopy and thermal analysis. From data of these investigations the structural formula and the mode of bonding were obtained. These complexes were successfully applied to sensitization of nano-crystalline TiO2 based solar cells (DSSCs). The photovoltaic efficiencies of the studied DSSCs increase in the following order [Ru(DHZ)2(bpy)]< [Ru(SCN)2(bpy)(DMSO)2]< [Ru(SCN)2(dmbpy)(DMSO)2]< [RuCl2(salen)]-2. This increase is in agreement with the light harvesting of these complexes as indicated from their absorption spectra. Ferrioxalate complex enhanced the performance of some investigated cells. Therefore, a mechanism of this improvement has been postulated. Polyaniline as well as iodine doped polyaniline modified FTO electrode has been tested as promising counter electrodes. The efficiencies of the cells using iodine doped polyaniline is higher than that of polyaniline, which is assignable to the high conductivity of iodine.
Highlights
Dye-sensitized solar cells (DSSCs) have attracted considerable attention in recent years due to the possibility of low-cost conversion of photovoltaic energy[1,2]
The strong band at 1438 cm-1 assigned to ν-(N=N) in the free dithizone is shifted to 1444 cm-1 in the complex; the two bands assigned to ν-(C=S) and ν-(C=N) were shifted from 891 cm-1 and 1589 cm-1 to 763 cm-1 and 1596 cm-1, respectively indicating the coordination of dithizone with ruthenium[24]
It is clear that the [RuCl2(salen)]-2 complex showed the highest efficiency compared to other complexes, which is due to the good light harvesting ability of this complex as indicated from UV-Vis absorption spectra of complexes
Summary
Dye-sensitized solar cells (DSSCs) have attracted considerable attention in recent years due to the possibility of low-cost conversion of photovoltaic energy[1,2]. 2.2 Synthesis of complexes [Ru(DHZ)2(bpy)] was synthesized by adding an ethanolic solution of dithizone (0.106gm,0.413mmol) to an ethanolic solution of [RuCl2(bpy)(DMSO)2] (0.1gm,0.207mmol). The reaction mixture was stirred at reflux for 8h under nitrogen and reduced light. After cooling to the room temperature, a brown precipitate was formed, filtered off, washed several times with ethanol and dried at 60 °C. After the completion of the reaction, the solution is cooled to room temperature, the formed precipitate is filtered off, washed with ethanol several times and dried at 600C. The reaction mixture is cooled to room temperature, filtered and the filtrate was evaporated to dryness, the residual solid was dissolved in CH2Cl2.
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