The well-ordered TiO2 nanotube arrays with controlled aspect ratio are
fabricated via potentiostatic anodization. The aspect ratio of TiO2
nanotube array can be tuned conveniently by changing the water content in
electrolyte and anodization time. The formation of well-ordered TiO2
nanotube array is good for the photogenerated electron transfer. So, the
well-ordered TiO2 nanotube array photoelectrodes have been used to
fabricate dye-sensitized solar cells (DSSCs). It is found that, with the optimum
nanotube length and aspect ratio, DSSCs with TiO2 nanotube array
photoelectrodes show better photoelectric conversion efficiency (2.60%) than
that with TiO2 nanoparticles on Ti foil photoelectrode. It is
elucidated by the interfacial electron transport of DSSCs, which are
characterized quantitatively, using the electrochemical impedance spectra. The
DSSC with optimal nanotube length and aspect ratio displays the fastest
interfacial electron transfer and longer electron lifetime.