Sticky complexes : carboxylic acid-functionalized N-phenylpyridin-2-ylmethanimine ligands as anchoring domains for copper and ruthenium dye-sensitized solar cells

Four members of a series of N-phenylpyridin-2-ylmethanimine ligands (L) decorated with carboxylic acid functionalities have been prepared. The ligand design allows a copper(I) complex [CuL2]+ to bind to a TiO2 surface through the simultaneous use of two carboxylate anchoring domains. Complexes of the type [CuL2][PF6], [CuL(NCMe)2][PF6] and [Ru(bpy)2L][PF6]2 have been synthesized and characterized by 1H and 13C NMR and electronic absorption spectroscopies, mass spectrometry and, for four of the complexes, single crystal X-ray diffraction. Dye-sensitized solar cells (DSCs) have been fabricated using the new complexes and the performances of the dyes assessed. The copper(I) complexes show good surface coverage and tuning of the electrolyte and the electronic properties of the ligands is now required to enhance the efficiencies of the DSCs.