title: Organic sensitizers featuring a planar indeno[1,2-b]-thiophene for efficient dye-sensitized solar cells.
abstract: An efficient organic sensitizer (JK-306) featuring a planar indeno[1,2-b]thiophene as the π-linker of a bridging unit for dye-sensitized solar cells (DSSCs) was synthesized. The sensitizer had a strong molar absorption coefficient and a red-shifted absorption band compared with JK-305, which resulted in a significant increase in the short-circuit photocurrent density. We incorporated a highly congested bulky amino group into the 2',4'-dihexyloxybiphenyl-4-yl moiety, an electron donor, to diminish the charge recombination and to prevent aggregation of the sensitizer. Under standard AM 1.5G solar conditions, JK-306-sensitized cells in the presence of co-adsorbents chenodeoxycholic acid (CDCA) and 4-[bis(9,9-dimethyl-9H-fluoren-2-yl)amino]benzoic acid (HC-A), which afforded an overall conversion efficiency of 8.37% and 8.52%, respectively. Upon changing the I(-) /I3 (-) electrolyte to the Co(II) /Co(III) redox couple, the cell gave rise to a significantly improved conversion efficiency of 10.02% with the multifunctional HC-A, which is one of the highest values reported for DSSCs with a cobalt-based electrolyte. Furthermore, the JK-306-based solar cell with a polymer gel electrolyte revealed a high conversion efficiency of 7.61%, which is one of the highest values for cells based on organic sensitizers.
authors.affiliation: Photovoltaic Materials, Department of Material Chemistry, Korea University 2511 Sejong-Ro, Sejong 339-700, South Korea.
authors.forename: Kimin
authors.initials: K
authors.lastname: Lim
authors.forename: Myung Jong
authors.initials: MJ
authors.lastname: Ju
authors.forename: Juman
authors.initials: J
authors.lastname: Song
authors.forename: In Taek
authors.initials: IT
authors.lastname: Choi
authors.forename: Kwangsuk
authors.initials: K
authors.lastname: Do
authors.forename: Hyeju
authors.initials: H
authors.lastname: Choi
authors.forename: Kihyung
authors.initials: K
authors.lastname: Song
authors.forename: Hwan Kyu
authors.initials: HK
authors.lastname: Kim
authors.forename: Jaejung
authors.initials: J
authors.lastname: Ko
mesh_terms: D004396:Coloring Agents / Q000737:chemistry*; D003487:Cyanoacrylates / Q000737:chemistry; D058266:Dielectric Spectroscopy; D011211:Electric Power Supplies; D004579:Electron Transport; D007192:Indenes / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D012993:Solar Energy; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D004396:Coloring Agents; D003487:Cyanoacrylates; D007192:Indenes; D013876:Thiophenes
keywords: cobalt; electrolytes; impedance; sensitizers; solar cells