Spectroscopic, electrochemical and photophysical properties of the novel complex tetracyano-1,10-phenanthroline-5,6-dione-ruthenate(II) and its application as a sensitizer in solar cells

Abstract

The new complex tetracyano-1,10-phenanthroline-5,6-dione-ruthenate(II) was synthesized as potassium and bis(triphenylphosphine)iminium salts and characterized by spectroscopic, electrochemical and photophysical techniques, with experimental results in agreement with quantum–mechanical calculations by Density Functional Theory. The structure of this anion was determined by Nuclear Magnetic Resonance. Although it emits weakly at room temperature in water with a lifetime in the nanosecond regime, the quinone moiety of the coordinated phenanthroline ligand allows its anchoring to mesoporous titanium dioxide films, thus leading to its application as a sensitizer in solar cells. Irradiated with a solar simulator, cells assembled with these dye-sensitized films, platinum as counter-electrodes and iodine/iodide redox mediators dissolved in acetonitrile or dimethylformamide, exhibit increasing efficiency of conversion of light into electrical energy with decreasing acceptor number of the solvent.