Nano Archive

Surface modification of stretched TiO2 nanotubes for solid-state dye-sensitized solar cells

Kang, Soon Hyung and Kim, Jae-Yup and Kim, Yukyeong and Kim, Hyun Sik and Sung, Yung-Eun (2007) Surface modification of stretched TiO2 nanotubes for solid-state dye-sensitized solar cells. JOURNAL OF PHYSICAL CHEMISTRY C, 111 (26). pp. 9614-9623.

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Official URL: http://dx.doi.org/10.1021/jp071504n

Abstract

Straight-stranded anatase TiO2 nanotubes were produced by anodic oxidation on a pure titanium substrate in an aqueous solution containing a 0.45 wt % NaF electrolyte (pH 4.3 fixed). The average length of the TiO2 nanotubes was approximately 3 mu m, which had an effect on the level of dye adsorption in the dye-sensitized solar cells. The anodic TiO2 nanotubes were applied as a working electrode in a solid-state dye-sensitized solar cell. An approximately 1 nm ZnO shell was coated on the TiO2 nanotube to improve the open-circuit voltage (V-oc) and conversion efficiency of the solar cell, and to retard any back reaction. Although the V-oc and short-circuit current (J(sc)) of the cell were improved, there was a low fill factor as a result of the formation of a thick TiO2 barrier layer in the anodic TiO2/Ti substrate. A parameter on the degradation of fill factor (37%) is related to the formation of a thick TiO2 barrier layer in the anodic TiO2/Ti substrate interface. A hydrogen peroxide treatment was performed in an attempt to narrow the TiO2 barrier layer. This treatment was found to influence not only fill factor (37-49%) but also the conversion efficiency (0.704-0.906%) of the cell by eliminating the remnant after anodic reaction and barrier narrowing through an etching effect. This result was confirmed by X-ray photoelectron spectroscopy (XPS) and photocurrent-voltage measurements. The longer electron lifetime on the ZnO coated TiO2 film was measured by the open-circuit voltage decay. The improvement in the electron lifetime from the thin ZnO coating affects the number of electrons collected on the Ti substrate and the retardation of charge recombination. Therefore, the ZnO coating on the TiO2 nanotube film improves the efficiency of dye-sensitized TiO2 solar cells from the extended V-oc from ZnO coating confirmed by the Mott-Schottky plots and the increased J(sc) through the inhibition of charge recombination confirmed by IPCE measurements.

Item Type:Article
Subjects:Physical Science > Nanophysics
Material Science > Nanofabrication processes and tools
Physical Science > Nano objects
Technology > Nanotechnology and energy applications
ID Code:3210
Deposited By:Anuj Seth
Deposited On:14 Jan 2009 16:35
Last Modified:09 Sep 2010 16:25

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