The novel pyridine based symmetrical Schiff base ligand and its transition metal complexes: synthesis,spectral definitions and application in dye sensitized solar cells (DSSCs)

The pyridine based azo-linked symmetrical Schiff base ligand, (E)-2,2′-((1E,1′E)-(pyridine-2,6-diylbis(azanylylidene))bis(methanylylidene))bis(4-((E)-phenyldiazenyl)phenol) (H₂L), and its Co(II), Ni(II) and Pd(II) transition metal complexes were prepared, and defined by using elemental analysis, Fourier transform infrared, UV–visible, mass, nuclear magnetic resonance spectra, molar conductance, magnetic susceptibility and thermal analysis techniques. The conductivity results pointed out the non-electrolytic nature of all metal complexes. Elemental composition, ultraviolet spectra and magnetic susceptibility data showed that the synthesized complexes are in the binuclear structure and square plane geometry. When compared to the characteristic infrared bands for the functional groups of the ligand structure with complex molecules are reached, the ligand binds to the metal atom via phenolic OH and azomethine-nitrogen. Furthermore, the dye-sensitized solar cells (DSSCs) based on H₂L and its metal complexes were fabricated, and photovoltaic properties of these devices were also investigated. The power conversion efficiency of fabricated devices based on ligand H₂L can be improved with the incorporation of the transition metal complex.