TiO2 nanotube arrays are very attractive for dye-sensitized solar cells (DSSCs) owing to their superior charge percolation and slower charge recombination. Highly ordered, vertically aligned TiO2 nanotube arrays have been fabricated by a three-step anodization process. Although the use of a one-dimensional structure provides an enhanced photoelectrical performance, the smaller surface area reduces the adsorption of dye on the TiO2 surface. To overcome this problem, we investigated the effect of DSSCs constructed with a multilayer photoelectrode made of TiO2 nanoparticles and TiO2 nanotube arrays. We fabricated the novel multilayer photoelectrode via a layer-by-layer assembly process and thoroughly investigated the effect of various structures on the sample efficiency. The DSSC with a four-layer photoelectrode exhibited a maximum conversion efficiency of 7.22% because of effective electron transport and enhanced adsorption of dye on the TiO2 surface.
Keywords: Anodic oxidation; Composite layer; DSSCs; Photoelectrode; TiO2 nanotube array.