Copper() and cobalt() Schiff base complexes with hydroxy anchors as sensitizers in dye-sensitized solar cells (DSSCs)

Two Schiff base complexes of copper( ii ) and cobalt( iii ) having the formulae [CuL 2 ] ( Cu-Sal ) and [CoL 3 ] ( Co-Sal ) (HL = 2-(((2-hydroxyethyl)imino)methyl)phenol) have been synthesized and characterized microanalytically, spectroscopically and in the case of Cu-Sal using single crystal X-ray diffraction technique. The single crystal X-ray analysis reveals a square planar geometry around Cu( ii ) satisfied by phenoxide oxygen and imine nitrogen of the L − ligand to generate a six membered chelate ring. The solid state structure of Cu-Sal is satisfied by varied intermolecular non-covalent interactions. The nature of these interactions has been addressed with the aid of Hirshfeld surface analysis. Both compounds have been used as sensitizers in TiO 2 based dye sensitized solar cells (DSSCs) and the DSSC experiments revealed that Co-Sal offers better photovoltaic performance in comparison to Cu-Sal . The Co-Sal exhibited a J sc of 9.75 mA cm −2 with a V oc of −0.648 V, incident photon to current conversion efficiency (IPCE) of 57% and η of 3.84%. The relatively better photovoltaic performance of Co-Sal could be attributed to better light absorption and dye loading than that of Cu-Sal . Two new imine based cobalt and copper complexes synthesized and used as sensitizers in DSSCs.