Electrochemical characterisation of TiO sub(2) nanotube array photoanodes for dye-sensitized solar cell application

• Published in: Solar energy materials and solar cells 2015-02, Vol.133, p.76-81
• Main Authors: Kanta, A-F, Poelman, M, Decroly, A
• Format: Article
• Language: English
• Subjects: Annealing; Arrays; Electrochemical impedance spectroscopy; Nanostructure; Photovoltaic cells; Precipitates; Solar cells; Titanium dioxide
• ISSN: 0927-0248
• DOI: 10.1016/j.solmat.2014.10.029

TiO sub(2) nanotubes have demonstrated perspective applications in the photovoltaic field. They can reduce both the transport dimensionality and the recombination of the photoinjected electrons. In this paper, arrays of TiO sub(2) nanotubes were fabricated by anodization of Ti foils in an ethylene glycol solution containing hydrofluoric acid (HF) under a constant voltage. From field emission scanning electron microscopy (FE-SEM) images, we observed the microstructure of titania nanotubes. Images show that, as-anodized, the surface of the nanotubes is covered with a precipitate. Ultrasonic treatment was used to remove this precipitate. X-ray diffraction (XRD) results show that the as-anodized amorphous TiO sub(2) nanotubes are converted to crystalline anatase after the samples have been annealed at 500 [degrees]C during 2 h. Electrochemical behaviour (in terms of charge transfer resistance) was investigated by electrochemical impedance spectroscopy (EIS). The annealed samples were characterized by electrochemical tests. A schematic representation of the TiO sub(2) nanotubes consisting of two layers (i.e. dense and nanoporous) is proposed to explain the obtained results.