Synthesis and Characterization of Photoanode by Immobilisation of Pyridyl Complexes on ITO for Photo-Conversion System

Abstract

Increasing developments on the application of copper complexes as dyes are due to their dual function in dye-sensitized solar cells (DSSCs) as redox mediators and dye sensitizers. The economical (abundance, low cost) and environmentally friendly properties of copper motivate researchers on the use of copper complexes for replacement of ruthenium-based dyes in solar cells. A novel [Cu(I)(2,9-dmp)(phen-dione)]PF6 (A2) bearing polypyridyl ligands, 1,10- phenanthroline-5,6-dione (phen-dione), 2,9-dimethyl-1,10-phenanthroline (dmp) was prepared by metal complexation reaction. The photofunctionality of A2 as a promising photosensitizer in DSSCs was studied. Interestingly, A2 exhibited two absorption peaks, one is detected in the ultraviolet region due to pi-pi* transition and the other is a metal-to-ligand charge transfer (MLCT) band at 405nm in the visible region. A2 was compared to the same complex with Cu(II) ion as the metal centre which only absorbed light in the ultraviolet region thereby implying limited use of Cu(II) complex in its light harvesting application. The photofunctionality of A2 was studied by employing it as an active material for photoelectric conversion by engaging it with ITO to create a photoanode. Upon light irradiation, an anodic current was observed. In conclusion, introduction of Cu(I), instead of Cu(II), in polypridyls ligands resulted in successful enhancement of photophysical properties of A2, making the photoanode of A2 suitable for light harvesting applications.