Preparation of lamina-shape TiO2 nanoarray electrode and its electron transport in dye-sensitized solar cells

Abstract

Lamina-shape TiO2 nanoarrays (LTNA) film electrode which is vertically grown on the surface of a Ti sheet by the means of hydrogen peroxide oriented etching at low temperature. X-ray diffraction shows that amorphous phase transforms to highly-crystalline anatase phase of the LTNA film after having been calcined at 500 ℃ for 1 h. Field emission scanning electron microscope exhibits a vertically oriented lamina-shape array with the morphology uniformly distributed and perfectly coated on the surface of Ti sheet, and the average height (film thickness), width and thickness of the leave are 1.35 m, 3080 nm and 1015 nm respectively, after 1 d etching in hydrogen peroxide at 80 ℃. The LTNA electrodes exhibit similar morphologies except for the film with a thickness of 2.12 m by hydrogen peroxide etching for 2 d. Using the LTNA film electrode as photoanode based on dye C106 fabricate back-illumination type dye-sensitized solar cell (DSC), a power conversion efficiency can reach 3.2% under an irradiation of air mass 1.5 global (100 mWcm-2) simulated sunlight. Mesoporous TiO2 films are also used in the fabrication of DSC under similar conditions. The devices are compared with each other by transient photoelectric attenuation and electrical impedance technique. The results demonstrate that the LTNA-electrode DSC has a much lower recombination rate and a longer electron life time.