Synthesis and Characterization of Heteroleptic Ru(II) Complexes Based on 4,4-Bis((E)-styryl)-2,2-bipyridine as Ancillary Ligand and Application for Dye-Sensitized Solar Cells

Abstract

Heteroleptic Ru(II) complexes were designed based on 4,4-bis((E)-styryl)-2,2-bipyridine (bsbpy) as an ancillary ligand for dye-sensitized solar cells (DSSCs), and those Ru(II) sensitizers, [Ru(L)(bsbpy)(NCS)(2)][TBA] (TBA; tetrabutylammonium), were synthesized according to a typical one-pot reaction of [RuCl2(p-cymene)](2) with the corresponding anchoring ligands (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)). The new Ru(II) dyes, [Ru(L)(bsbpy)(NCS)(2)][TBA] that incorporated vinyl spacer(s) into ancillary and/or anchoring ligand displayed red-shifted bands over the overall UV/VIS region relative to the absorption spectra of N719. A combination of bsbpy ancillary and dcphen anchoring ligand showed the best result for the overall power conversion efficiency (); i.e., a DSSC fabricated with [Ru(dcphen)(bsbpy)(NCS)(2)][TBA] exhibited a power conversion efficiency () of 2.98% (compare to N719, 4.82%).