title: A highly conjugated benzimidazole carbene-based ruthenium sensitizer for dye-sensitized solar cells.
abstract: A new type of carbene-based ruthenium sensitizer, CB104, with a highly conjugated ancillary ligand, diphenylvinylthiophene-substituted benzimidazolepyridine, was designed and developed for dye-sensitized solar cell applications. The influence of the thiophene antenna on the performance of the cell anchored with CB104 was investigated. Compared with the dye CBTR, the conjugated thiophene in the ancillary ligand of CB104 enhanced the molar extinction coefficient of the intraligand π-π* transition and the intensity of the lower energy metal-to-ligand charge-transfer band. However, the incident photon-to-current conversion efficiency spectrum of the cell anchored with CB104 (0.15 mM) showed a maximum of 63 % at 420 nm. The cell sensitized with the dye CB104 attained a power conversion efficiency of 7.30 %, which was lower than that of the cell with nonconjugated sensitizer CBTR (8.92 %) under the same fabrication conditions. The variation in the performance of these two dyes demonstrated that elongating the conjugated light-harvesting antenna resulted in the reduction of short-circuit photocurrent density, which might have been due to the aggregation of dye molecules. In the presence of a coabsorbate, chenodeoxycholic acid, the CB104-sensitized cell exhibited an enhanced photocurrent density and achieved a photovoltaic efficiency of 8.36 %.
authors.affiliation: Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei, Taiwan 10608, ROC.
authors.forename: Shih-Yu
authors.initials: SY
authors.lastname: Ho
authors.forename: Chaochin
authors.initials: C
authors.lastname: Su
authors.forename: Chung-Yen
authors.initials: CY
authors.lastname: Li
authors.forename: Kumaresan
authors.initials: K
authors.lastname: Prabakaran
authors.forename: Ming-Tai
authors.initials: MT
authors.lastname: Shen
authors.forename: Ying-Fan
authors.initials: YF
authors.lastname: Chen
authors.forename: Wei-Chun
authors.initials: WC
authors.lastname: Chang
authors.forename: Yogesh S
authors.initials: YS
authors.lastname: Tingare
authors.forename: Suribabu
authors.initials: S
authors.lastname: Akula
authors.forename: Sheng-Han
authors.initials: SH
authors.lastname: Tsai
authors.forename: Wen-Ren
authors.initials: WR
authors.lastname: Li
keywords: carbene ligands; dyes/pigments; ruthenium; sensitizers; solar cells