Open-top TiO2 nanotube arrays with enhanced photovoltaic and photochemical performances via a micromechanical cleavage approach

Anodic growth of TiO2 nanotube (NT) arrays has been proved to be very promising for energy conversion applications, e.g. in photovoltaic devices and fuel cells. However, disordered nano-grass layers were always found on the top of the anodic TiO2 NT arrays. In this paper, we demonstrate a novel and simple method using a micromechanical cleavage technique to peel off the disordered nanograss layer. Using this method, similar to 1 x 1.5 cm(-2) of uncapped TiO2 NT arrays with a high-aspect ratio can be easily obtained. The results further indicate that the treatment can improve the photovoltaic and photochemical performances. After the treatment, the conversion efficiency (h) of the dye sensitized solar cells (DSSCs) increased by 29.3%. This work facilitates the growth and applications of high aspect-ratio anodic TiO2 NT arrays in related devices and systems.