Infiltration of Spiro-MeOTAD hole transporting material into nanotubular TiO2 electrode for solid-state dye-sensitized solar cells

•We report infiltration of Spiro-MeOTAD into pores of TiO2 nanotube (TNT) arrays.•Surface amount of D35 is diffusion limited for TiO2 mesoporous film but not for TNTs.•Performance of liquid and solid-state solar cells based on TNTs is compared.

TiO2 nanotubes grown by anodic oxidation of Ti thin film deposited on conducting transparent fluoride-doped tin oxide (FTO) substrate were used as a unique geometrically organized template to study the infiltration of Spiro-MeOTAD hole transporting material (HTM) inside straight pores. The TiO2 nanotube (TNT) array electrode was compared with a mesoporous one in terms of loading with an organic dye of high extinction coefficient. It was shown that it is possible to build a working solid state dye sensitized solar cell device with such a combination of materials and its performance was compared with a device in which the solid state HTM was replaced by a liquid state electrolyte.