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A dyadic sensitizer for dye solar cells with high energy-transfer efficiency in the device

: Siegers, C.; Hohl-Ebinger, J.; Zimmerrnann, B.; Würfel, U.; Mülhaupt, R.; Hinsch, A.; Haag, R.


ChemPhysChem 8 (2007), No.10, pp.1548-1556
ISSN: 1439-4235
ISSN: 1439-7641
Journal Article
Fraunhofer ISE ()

A new bichromophoric dyad based on an alkyl-functionalized aminonaphthalimide as energy-donor chromophore and [Ru-(dcbpy)(2)(acac)]Cl (dcbpy=4,4'-dicarboxybipyridine, acac=acetylacetonato) as energy acceptor and sensitizing chromophore is synthesized. Efficient quenching of the donor-chromophore emission is observed in solution, presumably due to resonant energy transfer. This dyad is then used as a sensitizer in a dye solar cell. By comparing the spectral properties of transparent dye solar cells sensitized with the dyad and [Ru(dcbpy)(2)(acac)]Cl, it is possible to demonstrate that photons absorbed by the donor moiety also contribute significantly to the generation of current. Instead of using acceptor luminescence as a probe, enhanced photocurrent generation is employed to estimate the energy-transfer efficiency. Fitting theoretical to experimental external quantum efficiency functions gives a value for the energy-transfer efficiency of 85%. Evaluation of the maximum output power of dye solar cells sensitized with the dyad and [Ru(dcbpy)(2)(acac)]Cl showed, under selective illumination at the absorption maximum of the donor chromophore, that the introduction of the energy-donor moiety leads to a significant increase in the monochromatic maximum output power under blue illumination. This result demonstrates the usefulness of energy transfer for the generation of current in dye-sensitized solar cells.