Properties Improvement Of TiO₂ Nanotube Arrays And Their Application In Dye-Sensitized Solar Cells

TiO₂ nanotubular structures have attracted extensive attentions due to their unique properties used in various functional applications. We improved the method of anodization, which is the most common method for fabricating TiO₂ nanotube array films, and prepared TiO₂ nanotube films with better properties. Then we assembled front-side illuminated dye-sensitized solar cells (DSSCs), and investigated their performances.The influence of temperature on the fabrication of anodized TiO₂ nanotube arrays on Ti foils was investigated. Long tubes with larger pore diameters and thinner walls could be obtained with a fast growth rate at higher temperatures while regularity preserved. With the protection of a thermal layer during the two-step anodization, collapse was absent at high temperatures or extended periods. The temperature dependent growth was also found in accord with the high field model. The rapidly fabricated TiO₂ nanotubes with good quality and high porosity may have broad potential applications.TiO₂ nanotube arrays with uniform diameter from top to bottom were fabricated. The synthesizing approach is based on the investigation of the influence of electrolyte temperature on the tube diameter. We found that the inner diameter of the tubes increased with the electrolyte temperature. Accordingly, we improved the tube profile from the general V-shape to U-shape by raising the electrolyte temperature gradually. This is a simple and fast approach to fabricate uniform TiO₂ nanotubes in diameter. The improved TiO₂ nanotube arrays may show better properties and have broad potential applications.We developed a first direct synthesis of free-standing TiO₂ nanotube membranes based on self-detaching electrochemical anodization. The films with high-quality surfaces and both-end-open tubes could be obtained by appropriate thermal treatment during the process. The membranes are optically transparent after subsequent annealing to induce crystallization. The possible mechanism of the multi-step electrochemical process is also presented. This self-detaching process developed here is easy and efficient without additional chemical dissolution or etching and is shown to open new prospects for the application of TiO₂ nanotubes in various fields.We transferd the free-standing TiO₂ nanotube membranes, obtained through self-detaching electrochemical anodization, to FTO glass, and assembled DSSCs. After measuring the J-V curves, we find that DSSCs assembled with both-end-open membranes have the highest efficiency. The efficiency is 5.32%, with the tube length of 20?m. The longer the tubes the higher the efficiency. In conclusion, this method for assembling DSSCs is simple and efficient.