Conductive polymers have been widely applied as counter electrodes in dye-sensitized solar cells. However, as one of many materials in the conductive polymer family, polypyrrole attracts little attention in this field. In this paper, polypyrrole (PPy) was synthesized by vapour phase polymerization (VPP) and electropolymerization (EP) and these PPys were employed as counter electrodes in dye-sensitized solar cells. Comparing this to the regularly used Pt counter electrode, both of them show good catalytic behaviour in dye-sensitized solar cells though the PPy electrodes have a slightly lower fill factor. Such investigation will broaden the application of conductive polymers in DSCs. Our study indicates that polypyrrole is a good candidate to replace the Pt counter electrode in DSCs. Taking into consideration the regular solvent used in DSCs, it is recommended that an insoluble conductive polymer is a good choice for the counter electrode in DSCs.

Poly(3,4-ethylenedioxythiophene) (PEDOT) is an excellent kind of conducting polymer, comparable to Pt in catalytic behavior in dye-sensitized solar cells. Electrochemical polymerization in the presence of different anions (doping ions) that work as counterions of the resulting oxidized state PEDOT has been carried out to verify the influence of doping ions on the photo-electron conversion performance in dye-sensitized solar cells. Electrochemical and photo-electrochemical measurements reveal that the interaction between polymer and substrate (FTO) directly influences the fill factor in I–V curves, especially in the PEDOT–PSS system.

A hydrophobic and 2-thiophen-2-yl-vinyl-conjugated ruthenium complex, cis-Ru(dhtbpy)(dcbpy)(NCS)₂ [dhtbpy = 4,4′-di(hexylthienylvinyl)-2,2′-bipyridyl; dcbpy = 4,4′-dicarboxy-2,2′-bipyridyl], was newly designed, synthesized and applied successfully to sensitization of nanocrystalline TiO₂-based solar cells, giving a conversion efficiency of 9.5% under irradiation with AM 1.5 solar light.