Dinuclear Ru(II) complexes bridged with 5-(2-[2,2′-bipyridin]-5-ylethynyl)-2,2′-bipyridine ligand and ligated to ancillary α-diimine ligand: synthesis and application to dye-sensitized solar cells

Abstract

Four heteroleptic dinuclear ruthenium(II) complexes bridged with 5-(2-[2,2'-bipyridin]-5-ylethynyl)-2,2'-bipyridine (bpy-ac-bpy) ligand were prepared and ligated to four different alpha-diimine ligands, [TBA](2)[Ru-2(L)(2)(BL)(NCS)(4)] [where L = 4,4'-dicarboxy-2,2'-bipyridine (dcbpy), 4,4'-bis(E-carboxyvinyl)-2,2'-bipyridine (dcvbpy), 4,7-dicarboxy-1,10-phenanthroline (dcphen), or 4,7-bis(E-carboxyvinyl)-1,10-phenanthroline (dcvphen), BL = bridging ligand]. Their physical and photovoltaic properties were investigated. Among the dye-sensitized solar cells (DSSCs) fabricated with the newly prepared four heteroleptic dinuclear ruthenium(II) complexes, a DSSC fabricated with the heteroleptic dinuclear ruthenium(II) complexes bridged with bpy-ac-bpy and ligated to dcvphen exhibited a reasonable power conversion efficiency (eta) of 2.33%, which is close to that of the N719-sensitized solar cell (3.44%) under the same cell fabrication and measuring conditions.