Fabrication of dye-sensitized solar cells using a both-ends-opened TiO 2 nanotube/nanoparticle hetero-nanostructure

Abstract

Abstract We fabricated a hetero-structure photoanode with both-ends-opened TiO2 nanotubes and TiO2 nanoparticles for dye-sensitized solar cells (DSSCs). Two-step anodization and selective etching process were used to obtain the both-ends-opened TiO2 nanotubes. A heat treatment was employed to obtain anatase crystal-structured nanotubes. The effect of the both-ends-opened TiO2 nanotubes on the photoelectric conversion efficiency (PCE) of the DSSCs was evaluated by positioning the TiO2 nanotubes on TiO2 nanoparticle layers and by sandwiching them between the TiO2 nanoparticles. It is suggested that both-ends-opened TiO2 nanotubes serve as incident light scattering layers that lead to superior light harvesting efficiency of DSSCs. This increases the electron lifetime and results in the recycling of more light by dye molecules, thus increasing the photocurrent density. Consequently, a high PCE of 7.74% was obtained when the TiO2 nanotubes were placed on the TiO2 nanoparticles and a PCE of 8.56% was obtained when the TiO2 nanotubes were placed between the TiO2 nanoparticles.