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Integrating a Triplet-triplet Annihilation Up-conversion System to Enhance Dye-sensitized Solar Cell Response to Sub-bandgap Light
Published on: September 12, 2014
Sensitized triplet-triplet annihilation upconversion in water and its application to photochemical transformations
Christoph Kerzig1, Oliver S Wenger1
1Department of Chemistry , University of Basel , St. Johanns-Ring 19 , 4056 Basel , Switzerland . Email: christoph.kerzig@unibas.ch ;
Abstract:
Sensitized triplet-triplet annihilation (TTA) is a promising mechanism for solar energy conversion, but so far its application has been practically completely limited to organic solvents and self-assembled or solid state systems. Combining water-soluble ruthenium complex-pyrene dyads with particularly long excited-state lifetimes as sensitizers and highly fluorescent commercial anthracenes as acceptors/annihilators, we were able to achieve green-to-violet upconversion with unprecedented quantum yields in pure water. Compared to the only known system exploiting sensitized TTA in homogeneous aqueous solution, we improve the overall photon upconversion efficiency by a full order of magnitude and present the very first example for a chemical transformation on a laboratory scale via upconversion in water. Specifically, we found that a thermodynamically challenging carbon-chlorine bond activation can be driven by green photons from an inexpensive continuous wave light source in the presence of dissolved oxygen. Our study is thus potentially relevant in the context of cleaning water from halogenated (toxic) contaminants and for sustainable photochemistry in the most environmentally friendly solvent.
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