文摘
We report a combined experimental and computational study of several ruthenium(II) sensitizersoriginated from the [Ru(dcbpyH2)2(NCS)2], N3, and [Ru(dcbpyH2)(tdbpy)(NCS)2], N621, (dcbpyH2 = 4,4'-dicarboxy-2,2'-bipyridine, tdbpy = 4,4'-tridecyl-2,2'-bipyridine) complexes. A purification procedure wasdeveloped to obtain pure N-bonded isomers of both types of sensitizers. The photovoltaic data of the purifiedN3 and N621 sensitizers adsorbed on TiO2 films in their monoprotonated and diprotonated state, exhibitedremarkable power conversion efficiency at 1 sun, 11.18 and 9.57%, respectively. An extensive DensityFunctional Theory (DFT)-Time Dependent DFT study of these sensitizers in solution was performed,investigating the effect of protonation of the terminal carboxylic groups and of the counterions on theelectronic structure and optical properties of the dyes. The calculated absorption spectra are in goodagreement with the experiment, thus allowing a detailed assignment of the UV-vis spectral features of thetwo types of dyes. The computed alignments of the molecular orbitals of the different complexes with theband edges of a model TiO2 nanoparticle provide additional insights into the electronic factors governingthe efficiency of dye-sensitized solar cell devices.
