Journal of Physical Chemistry B 2005-10-13

Molecular adjustment of the electronic properties of nanoporous electrodes in dye-sensitized solar cells.

Sven Rühle, Miri Greenshtein, S-G Chen, Alexandra Merson, Hillel Pizem, Chaim S Sukenik, David Cahen, Arie Zaban

Index: J. Phys. Chem. B 109 , 18907, (2005)

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Abstract

Molecular modification of dye-sensitized, mesoporous TiO2 electrodes changes their electronic properties. We show that the open-circuit voltage (V(oc)) of dye-sensitized solar cells varies linearly with the dipole moment of coadsorbed phosphonic, benzoic, and dicarboxylic acid derivatives. A similar dependence is observed for the short-circuit current density (I(sc)). Photovoltage spectroscopy measurements show a shift of the signal onset as a function of dipole moment. We explain the dipole dependence of the V(oc) in terms of a TiO2 conduction band shift with respect to the redox potential of the electrolyte, which is partially followed by the energy level of the dye. The I(sc) shift is explained by a dipole-dependent driving force for the electron current and a dipole-dependent recombination current.