Charge separation and efficient light energy conversion in sensitized mesoscopic solar cells based on binary ionic liquids.
A 7.4% power conversion efficiency at air mass (AM) 1.5 full sunlight was reached with a mesoscopic solar cell employing a new binary ionic liquid electrolyte composed of 1-propyl-3-methylimidazolium iodide and 1-ethyl-3-methylimidazolium tricyanomethanide in conjunction with the amphiphilic ruthenium complex NaRu(4-carboxylic acid-4'-carboxylate)(4,4'-dinonyl-2,2'-bipyridine)(NCS)(2), coded as Z-907Na. Ultramicroelectrode voltammetric, nanosecond laser transient absorbance, and photovoltaic measurements show that a high iodide concentration is required for dye regeneration to compete efficiently with charge recombination. A surprisingly fast reductive quenching process is turned on in pure iodide melts. This channel is unproductive, explaining the lower photocurrents observed under these conditions.
Wang
Peng
P
Laboratory for Photonics and Interfaces, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland.
Wenger
Bernard
B
Humphry-Baker
Robin
R
Moser
Jacques-E
JE
Teuscher
Joël
J
Kantlehner
Willi
W
Mezger
Jochen
J
Stoyanov
Edmont V
EV
Zakeeruddin
Shaik M
SM
Grätzel
Michael
M