Infoscience

Journal article

Combining a Small Hole-Conductor Molecule for Efficient Dye Regeneration and a Hole-Conducting Polymer in a Solid-State Dye-Sensitized Solar Cell

In dye-sensitized solar cells an efficient transfer of holes from the oxidized dye to the contact is necessary, which in solid-state dye-sensitized solar cells is performed by hole-conductor mols. In this report we use photoinduced absorption and transient absorption spectroscopy to show that a small hole-conducting mol., tris(p-anisyl)amine, regenerates dye mols. in the pores of the dye-sensitized TiO2 nanoparticle electrode efficiently even for thick (>5 μm) electrodes. For similar thicknesses we observe incomplete regeneration using a larger polymer hole-conductor. However, the performance of the solar cells with the small hole-conductor mols. is poor due to that inefficient hole conduction in these small mols. may limit the collection of the charges at the contacts. Polymer hole-conductors, which may have a good hole cond., also have a high mol. wt., which makes these polymers difficult to infiltrate into the smallest pores in the electrode. We show that a conducting polymer, poly(3-hexylthiophene), may be added to the small mol. hole-conductor, to enable better transport of the charges to the contact and to reduce recombination and therefore increase the photocurrent. This new device construction with a small mol. efficiently regenerating the dye mols., and a polymer conducting the holes to the contact is therefore a promising pathway for solid-state dye-sensitized solar cells.

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