Web Release Date: January 15,
Improved Photon-to-Current Conversion Efficiency with a Nanoporous p-Type NiO Electrode by the Use of a Sensitizer-Acceptor Dyad
and
Laboratoire de Synthèse Organique, UMR 6513 CNRS&FR CNRS 2465, Université de Nantes, Faculté des Sciences et des Techniques de Nantes, BP 92208; 2, rue de la Houssinière, 44322 Nantes Cedex 03, France, Chemical Physics, Department of Photochemistry and Molecular Science, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden, and Center of Molecular Devices, Department of Chemistry, Royal Institute of Technology, Teknikringen 30, 100 44 Stockholm, Sweden
Received: September 16, 2007
In Final Form: October 26, 2007
Abstract:
A peryleneimide sensitizer and a covalently linked peryleneimide-naphthalenediimide dyad were prepared and characterized by absorption and emission spectroscopies, electrochemistry, and spectroelectrochemistry. These compounds were chemisorbed on nanoporous nickel oxide electrodes and then studied by femtosecond transient absorption spectroscopy in the presence of a redox active electrolyte (I3-/I-). In both compounds, upon excitation of the peryleneimide unit, an electron is efficiently ejected from the valence band of NiO to the dye with an average time constant of approximately 0.5 ps. In the case of the dyad, the excess electron is shifted further onto the naphtalenediimide unit, creating a new charge separated state. The latter exhibits a substantial retardation of the charge recombination between the hole and the reduced molecule compared with the peryleneimide sensitizer. The photoaction spectra of a sandwich dye-sensitized solar cell (DSSC) composed of NiO films and these new dyes were recorded, and the absorbed-photon to current conversion efficiency (APCE) was three times higher with the dyad than with the peryleneimide dye: 45%. The maximum APCE of approximately 45% is the highest value reported for a DSSC based on a nanostructured metal oxide p-type semiconductor.
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