title: 4,4',5,5'-Tetracarboxy-2,2'-bipyridine Ru(II) sensitizers for dye-sensitized solar cells.
abstract: Two Ru(II) sensitizers TCR-1 and TCR-2 bearing four carboxy anchoring groups were prepared using 4,4',5,5'-tetraethoxycarbonyl-2,2'-bipyridine chelate and 4-(5-hexylthien-2-yl)-2-(3-trifluoromethyl-1H-pyrazol-5-yl)pyridine and 6-t-butyl-1-(3-trifluoromethyl-1H-pyrazol-5-yl)isoquinoline, respectively. Dissolution of these sensitizers in DMF solution afforded a light green solution up to 10(-5) M, for which their color gradually turned red upon further dilution and deposition on the surface of a TiO2 photoanode due to the spontaneous deprotonation of carboxylic acid groups. These sensitizers were characterized using electrochemical means and structural analysis time-dependent density functional theory (TDDFT) simulation and were also subjected to actual device fabrication. The as-fabricated DSC devices showed overall efficiencies η = 6.16% and 6.23% versus their 4,4'-dicarboxy counterparts TFRS-2 and TFRS-52 with higher efficiencies of 7.57% and 8.09%, using electrolyte with 0.2 M LiI additive. Their inferior efficiencies are possibly caused by the combination of blue-shifted absorption on TiO2, inadequate dye loading, and the perpendicularly oriented central carboxy groups.
authors: Department of Chemistry and Low Carbon Energy Research Center, National Tsing Hua University , Hsinchu 30013, Taiwan.
authors: Chun-Cheng
authors: CC
authors: Chou
authors: Fa-Chun
authors: FC
authors: Hu
authors: Kuan-Lin
authors: KL
authors: Wu
authors: Tainan
authors: T
authors: Duan
authors: Yun
authors: Y
authors: Chi
authors: Shih-Hung
authors: SH
authors: Liu
authors: Gene-Hsiang
authors: GH
authors: Lee
authors: Pi-Tai
authors: PT
authors: Chou