Dye-sensitized solar cells based on trench structured TiO2 nanotubes in Ti substrate

We have proposed dye-sensitized solar cells (DSSCs) with trench-type TiO2 nanotube structure to improve the low device efficiency of conventional TiO2 nanotube DSSCs using Ti substrate. Compared to the conventional standing-type TiO2 nanotube structure based DSSCs, the trench-type TiO2 nanotube structure based DSSCs have shown an improvement of device efficiency of approximately 40% due to the large increase of Jsc. In the trench-type TiO2 nanotube structure, the contact area between the TiO2 nanotube sidewall and the Ti substrate is significantly increased. This increase of contact area provides more charge transport paths than exist in the conventional standing-type TiO2 nanotube structure and reduces the electrical resistance between the Ti substrate and the TiO2 nanotubes. Therefore, the remarkable increase of Jsc is the result of the charge collection efficiency, which is improved due to the increase of contact area between the TiO2 nanotube sidewall and the Ti substrate in the trench-type TiO2 nanotube structure. The fabrication of the trench-type TiO2 nanotube structure is an effective manufacturing process for improving the device efficiency of TiO2 nanotube based DSSCs using Ti substrate. DSSCs having an 11.9 μm thick trench-type TiO2 nanotube structure have shown an efficiency of 5.74%.