The growth of TiO₂ nanotubes from sputter-deposited Ti film on transparent conducting glass for photovoltaic applications

In the present investigation, TiO₂ nanotube arrays were grown on the Titanium (Ti) films deposited on transparent conducting FTO (fluorine doped tin oxide) glasses for the application of dye sensitized solar cells (DSSCs). Highly adhesive Ti films were deposited on FTO substrates using the radio frequency (RF) magnetron sputtering technique with the thickness of about 1.36 and 1.83 μm at the sputtering durations of 5 and 8 h, respectively. The sputtering parameters including sputtering power, operating pressure and sputtering temperature were maintained at 120 W, 39 mbar and 200°C. Subsequently, TiO₂ nanotubes were fabricated on the sputtered Ti film by the electrochemical anodization method at an anodization voltage of 60 V. X-ray diffraction investigations revealed the formation of anatase phase TiO₂ nanotube arrays after annealing at 450°C. The diameter and length of the nanotubes were also estimated from scanning electron microscope analysis. In addition, TiO₂ nanotubes were decorated with TiO₂ nanoparticles and nanorods by surface modification processes. The photoelectric conversion efficiency of the DSSC fabricated with TiO₂ nanotube arrays was 1.90%. The devices using TiO₂ nanoparticles and nano-rods decorated nanotube photo-anodes showed enhanced photo-conversion efficiencies of 2.59 and 2.95%, respectively.