Highly crystalline Titania nanotube arrays realized by hydrothermal vapor route and used as front-illuminated photoanode in dye sensitized solar cells

• Highly crystalline TNTAs can be realized under low temperature by a new way.
• The TNTAs possessed excellent properties for light scattering and dye adsorption.
• The TNTAs exhibited better photovoltaic response than thermal annealing TNTAs.
• An optimum PCE of DSSCs based on the TNTAs can reach ∼8.11 ± 0.11%.

Highly crystalline TiO2 nanotube arrays (TNTAs) film is easily realized by treating its amorphous film under the hydrothermal vapor (HV) environment. The freestanding TNTAs film can be lift-off from the Ti foil, which serves as photoanode based on FTO substrate after the transplanting procedure. Compared to the thermal annealing (TA) treated TNTAs photoanode, the HV treated photoanode possesses some excellent properties, such as long optical path, fast charge transporting and easy adsorption of the sensitizer molecules, which can result in high short current density. Notably, the N719 dye sensitized HV treated photoanode prepared under 180 °C shows relatively high photovoltaic response in the visible range due to its hierarchical structure, which gives an impressive performance conversion efficiency of 8.11% without any surface modification. And the present work sheds light on the application of the mild crystalline strategy for performance improvement of the DSSCs based on TiO2 nanotube arrays photoanode.

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