title: Ion coordinating sensitizer for high efficiency mesoscopic dye-sensitized solar cells: influence of lithium ions on the photovoltaic performance of liquid and solid-state cells.
abstract: A Li+ coordinating sensitizer, NaRu(4-carboxylic acid-4'-carboxylate)(4,4'-bis[(triethylene glycol methyl ether) methyl ether]-2,2'-bipyridine)(NCS)2 (coded as K51), has been synthesized, and the effect of Li+ coordination on its performance in mesoscopic titanium dioxide dye-sensitized solar cells has been investigated. Fourier transform infrared spectra suggest that Li+ coordinates to the triethylene oxide methyl ether side chains on the dye molecules. With the addition of Li+ to a nonvolatile liquid electrolyte, we observe a significant increase in the photocurrent density, with only a small decrease in the open-circuit voltage, contrary to a non ion coordinating dye which displays a large drop in potential with the addition of Li+. For a solar cell incorporating an organic hole-transporter, we find the potential rises with increasing the Li+ concentration in the hole-transporter matrix. For the liquid electrolyte and solid-state cells, we obtain power conversion efficiencies of 7.8% and 3.8%, respectively, under simulated sunlight.
authors.affiliation: Laboratory for Photonics and Interfaces, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Daibin
authors.initials: D
authors.lastname: Kuang
authors.forename: Cedric
authors.initials: C
authors.lastname: Klein
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Snaith
authors.forename: Jacques-E
authors.initials: JE
authors.lastname: Moser
authors.forename: Robin
authors.initials: R
authors.lastname: Humphry-Baker
authors.forename: Pascal
authors.initials: P
authors.lastname: Comte
authors.forename: Shaik M
authors.initials: SM
authors.lastname: Zakeeruddin
authors.forename: Michael
authors.initials: M
authors.lastname: Grätzel
mesh_terms: D004396:Coloring Agents; D011211:Electric Power Supplies; D004563:Electrochemistry / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007477:Ions; D008027:Light; D008094:Lithium / Q000737:chemistry*; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000528:radiation effects; D036103:Nanotechnology / Q000295:instrumentation*; D044367:Phase Transition; D010777:Photochemistry / Q000295:instrumentation*; D014025:Titanium / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D004396:Coloring Agents; D007477:Ions; C009495:titanium dioxide; D008094:Lithium; D014025:Titanium