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Overcoming Kinetic Limitations of Electron Injection in the Dye Solar Cell via Coadsorption and FRET
Author(s) -
Siegers Conrad,
Würfel Uli,
Zistler Markus,
Gores Heiner,
HohlEbinger Jochen,
Hinsch Andreas,
Haag Rainer
Publication year - 2008
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200700864
Subject(s) - photochemistry , photocurrent , chromophore , acceptor , chemistry , electron transfer , solar cell , electron acceptor , photosensitizer , energy conversion efficiency , cyanine , moiety , förster resonance energy transfer , dye sensitized solar cell , materials science , optoelectronics , fluorescence , optics , organic chemistry , electrolyte , physics , electrode , condensed matter physics
A new, extremely simple concept for the use of energy transfer as a means to the enhancement of light absorption and current generation in the dye solar cell (DSC) is presented. This model study is based upon a carboxy‐functionalized 4‐aminonaphthalimide dye (carboxy‐fluorol) as donor, and (NBu 4 ) 2 [Ru(dcbpy) 2 (NCS) 2 ] (N719) as acceptor chromophores. A set of three different devices is assembled containing either exclusively carboxy‐fluorol or N719, or a mixture of both. This set of transparent devices is characterized via IV‐measurements under AM1.5G and monochromatic illumination and their light‐harvesting and external quantum efficiencies (LHE and EQE, respectively) are determined as well. It is shown that the device containing only the donor chromophore has a marginal power conversion efficiency, thus indicating that carboxy‐fluorol is a poor sensitizer for the DSC. Cyclovoltametric measurements show that the poor sensitization ability arises from the kinetic inhibition of electron injection into the TiO 2 conduction band. Comparing the spectral properties of the DSCs assembled presently, however, demonstrates that light absorbed by carboxy‐fluorol is almost quantitatively contributing to the photocurrent if N719 is present as an additional sensitizer. In this case, N719 acts as a catalyst for the sensitization of TiO 2 by carboxy‐fluorol in addition to being a photosensitizer. Evaluation of the maximum output power under blue illumination shows that the introduction of an energy‐donor moiety via coadsorption, leads to a significant increase in the monochromatic maximum output power. This result demonstrates that energy transfer between coadsorbed chromophores could be useful for the generation of current in dye‐sensitized solar cells.