Dye sensitized solar cell based on hydrothermally synthesized TiO₂ nanotubes

Abstract

Dye Sensitized Solar Cells (DSSCs) are promising alternative devices for conventional Silicon based photovoltaic devices. Electron transport in DSSC could be enhanced by fabricating TiO₂, nanotubes instead of TiO₂, nanoparticles. In this investigation, titania nanotubes were synthesized via hydrothermal treatment of commercially available TiO₂. powder and they were fabricated into DSSC. In DSSC, random nature of the TiO₂; nanocrystalline particle network results in electrons to recombine as they travel through the surface of the TiO₂ nanocrystalline particle network reducing the cell performance. In order to reduce the charge recombination thereby improve the cell performance, TiO₂ nanotubes can be utilized instead of TiO₂ nanocrystaline particle as they provide effective straight path way to electron transport. TiO₂ nanotubes were synthesized via hydrothermal treatment of TiO₂ (P25 Degussa) nanoparticles. Formation of nearly 10 nm diameter and average length of 200 nm TiO₂ nanotubes was confirmed by Scanning Electron Microscopy analysis.TiO₂ nanotubes based working electrode was prepared on a conducting substrate (FTO/F: SnO2) by electrophoretic deposition method. Electrolyte for electrophortic deposition was prepared based on two methods namely Precipitate Method and Powder Method. TiO₂ nanotube suspension prepared by ultra sonicating the precipitate is called Precipitate Method and TiO₂ nanotube powder made by freeze drying the precipitate is called Powder Method. The electrophoretic deposition method was employed to deposit TiO₂ nanotubes onto the conducting surface using two.electrode system. The electro deposition potential and time was optimized as ~40 V for 5 minutes and ~40 V for 4 minutes for Precipitate and Powder Methods respectively at room temperature. Finally, electrodes were treated with TiCl₄ to improve the performance.