Charge separation and efficient light energy conversion in sensitized mesoscopic solar cells based on binary ionic liquids

Peng Wang; Bernard Wenger; Robin Humphry-Baker; Jacques-E Moser; Joël Teuscher; Willi Kantlehner; Jochen Mezger; Edmont V Stoyanov; Shaik M Zakeeruddin; Michael Grätzel

doi:10.1021/ja042232u

Charge separation and efficient light energy conversion in sensitized mesoscopic solar cells based on binary ionic liquids

J Am Chem Soc. 2005 May 11;127(18):6850-6. doi: 10.1021/ja042232u.

Authors

Peng Wang¹, Bernard Wenger, Robin Humphry-Baker, Jacques-E Moser, Joël Teuscher, Willi Kantlehner, Jochen Mezger, Edmont V Stoyanov, Shaik M Zakeeruddin, Michael Grätzel

Affiliation

¹ Laboratory for Photonics and Interfaces, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland.

PMID: 15869308
DOI: 10.1021/ja042232u

Abstract

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.