Síntese e caracterização de bisbipiridinas de Ru com potencial aplicação como sensibilizadores de células solares

Abstract

In this work ruthenium bipyridine complexes of the type cis-[Ru(dcbpy)2(L)(L’)] (where dcbpy is 2,2-bipyridine-4,4-dicarboxylic acid; L is nicotinamide (nic) or isonicotinamide (isn) and L’ is Cl or SCN or nic) were synthesized and their electrochemical and photophysical properties were evaluated in order to verify their potential application as dye sensitizers in Dye Sensitized Solar Cells (DSSCs). These compounds were characterized by spectroscopic and electrochemical techniques. These complexes show metal-to-ligand charge transfer (MLCT) absorption centered at about 500 nm.Also, the compounds exhibit broad bands with maxima at 650 nm and low emission quantum yields. The result of cyclic voltammetry shows a redox couple at approximately 0.8 V vsAg/AgCl, which is positively shifted in comparison with the starting compound (~0.50V vs Ag/AgCl). The excited state oxidation potentials of both complexes (~ 1.5 V) are favorable for an efficient electron injection from the dye into the TiO2 conduction band.The photoelectrochemical data were evaluated in comparison to the standard [Ru(dcbH2)2(NCS)2] dye, N3. DSSCs sensitized by these compounds exhibit overall efficiency conversion of 0.38 and 0.47% for cis-[Ru(dcbpy)2(nic)Cl]+ and cis-[Ru(dcbpy)2(isn)Cl]+, respectively, while that for N3 is 2.70 % in the same condition. The lower adsorption and the higher charge recombination between the electrons injected into the TiO2 conduction band and oxidized dye molecules in comparison to N3 justify the lower global efficiencies observed than the N3 compound.