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 (η); i.e., a DSSC fabricated with [Ru(dcphen)(bsbpy)(NCS)2][TBA] exhibited a power conversion efficiency (η) of 2.98% (compare to N719, 4.82%).

Synthesis and Study of the Physical and Photovoltaic Properties of Novel Heteroleptic Ruthenium(II) Complexes Ligated with Highly π-Conjugated Bipyridine Ancillary and Phenanthroline Anchoring Ligand for Dye-Sensitized Solar Cells

“…e result corresponded to a PCE value of approximately 5.63%. e recorded value agreed well with the values previously reported by us [18]. e V OC , J SC , and FF values of an H3-sensitized DSSC were 0.64 V, 6.65 mA•cm −2 , and 0.69, respectively.…”

“…Two phenanthroline-based anchoring ligands functionalized with carboxylic acid groups and three highly π-conjugated and/or methoxy-incorporated conjugated bipyridine ancillary ligands were prepared for the synthesis of the new heteroleptic ruthenium(II) complex sensitizers for the fabrication of DSSC materials (Scheme 1). e anchoring ligands, which would enable the efficient chemisorption of the sensitizers onto the mesoporous oxide (dcphen and its π-conjugated dcvphen analog), were synthesized following reported protocols (Scheme 1(a)) [16,18]. ree ancillary ligands (4,4′-bis{2-(3,4-dimethoxyphenyl) ethenyl}-2,2′-bipyridine (dmpbpy), 4,4′-bis{2-(1,1′-biphenyl)-4-ylethenyl}-2,2′-bipyridine (bpbpy), and 4,4′-bis{2-(4′-methoxy-[1,1′-biphenyl]-4-ylethenyl}-2,2′-bipyridine (mbpbpy)) were synthesized over multiple steps starting from 4,4′-dimethylbipyridine following the methods reported in the literature [19].…”

“…For comparison, the UV-vis absorption spectrum of the well-known N719 has been shown in Figure 2. e data obtained by analyzing the UV-vis spectra recorded with N719 and the previously reported compound H3 (ruthenium(II) complex ligated to 4,4′-bis((E)-styryl)-2,2′bipyridine (bsbpy) and dcphen [18]) have also been listed in Table 1 for reference. e experiments were conducted with the compounds dissolved in DMSO (concentration:…”

“…Consequently, a series of novel heteroleptic ruthenium(II) complexes and dinuclear ruthenium(II) complexes that exhibited satisfactory PCE were synthesized. A series of compounds were synthesized by varying the ancillary and/or anchoring ligands [15][16][17][18][19]. During the course of our study, we realized that anchoring ligands other than the bcbpy-or terpyridinetype ligands could be used for the fabrication of efficient DSSCs.…”

“…e choice of the anchoring ligand is also important as efficient anchoring onto the mesoporous oxide surface can potentially improve the light-harvesting efficiency. In addition to well-known bipyridine-or terpyridine-type anchoring ligands, we attempted the less studied phenanthroline-based anchoring ligands for the fabrication of the sensitizers [16,18]. As it looks encouraging, we studied the 4,7-dicarboxy-1,10-phenanthroline (dcphen) ligand and its π-conjugated 4,7-bis(E-carboxyvinyl)-1,10phenanthroline (dcvphen) analog extensively in this study and determined their efficiency as anchoring ligands.…”