title: Tris-heteroleptic ruthenium-dipyrrinate chromophores in a dye-sensitized solar cell.
abstract: Two novel tris-heteroleptic Ru-dipyrrinates were prepared and tested as sensitizers in the dye-sensitized solar cell (DSSC). Under AM 1.5 sunlight, DSSCs employing these dyes achieved power conversion efficiencies (PCEs) of 3.4 and 2.2 %, substantially exceeding the value achieved previously with a bis-heteroleptic dye (0.75 %). As shown by electrochemical measurements and DFT calculations, the improved PCEs stem from the synthetically tuned electronic structure, which affords more negative excited state redox potentials and favorable electron injection into the TiO2 conduction band. Electron injection was quantified by nanosecond transient absorption spectroscopy, which revealed that the highest injection yield is achieved with the dye that acts as the strongest photoreductant.
authors.affiliation: Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32310 (USA).
authors.forename: Guocan
authors.initials: G
authors.lastname: Li
authors.forename: Ke
authors.initials: K
authors.lastname: Hu
authors.forename: Kiyoshi C D
authors.initials: KC
authors.lastname: Robson
authors.forename: Serge I
authors.initials: SI
authors.lastname: Gorelsky
authors.forename: Gerald J
authors.initials: GJ
authors.lastname: Meyer
authors.forename: Curtis P
authors.initials: CP
authors.lastname: Berlinguette
authors.forename: Michael
authors.initials: M
authors.lastname: Shatruk
keywords: N ligands; dye-sensitized solar cells; dyes/pigments; injection yield; ruthenium