Molecular adjustment of the electronic properties of nanoporous electrodes in dye-sensitized solar cells.
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.
Rühle
Sven
S
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel.
Greenshtein
Miri
M
Chen
S-G
SG
Merson
Alexandra
A
Pizem
Hillel
H
Sukenik
Chaim S
CS
Cahen
David
D
Zaban
Arie
A