Solid-state Ru-dye solar cells using polypyrrole as a hole conductor

Polypyrrole (Ppy) was prepared by a photoelectropolymerization technique using different current densities on Ru-dye sensitized titanium dioxide nanoporous films. Solar cells were constructed using gold as the counter electrode with Ppy acting as the hole conductor and current-voltage characteristics were measured revealing initial efficiencies of 0.06%. Time-current profiles and x-ray photoelectron data confirmed that Ppy growth occurs within the TiO2 pores and not at the 'extreme surface. Efficiency measurements of solar cells increased over one month and stabilized to nearly 1% this phenomenon being attributed to the intercalation of Li+ ions during the preparation step, which involved a dedoping process at a reduced potential and a soaking in LiClO4 solution.