Fabrication of dye-sensitized solar cells by transplanting highly ordered TiO2 nanotube arrays

Highly ordered TiO2 nanotube arrays fabricated by anodization are very attractive to dye-sensitized solar cells (DSCs) due to their superior charge percolation and slower charge recombination. However, the efficiency of TiO2-nanotube-based DSCs is 6.89%, which is still lower than that of TiO2-nanoparticle-based DSCs. We have suggested the transplanting the highly ordered TiO2 nanotube arrays to FTO glass to improve the performance of TiO2-nanotube-based DSCs. DSCs based on transplanted TiO2 nanotube arrays and TiO2 nanoparticles were fabricated by same process and materials to exclude the unexpected factors. In TiO2 thickness of ca. 15 μm, the efficiency of 2.91% in front-side illuminated DSCs based on TiO2 nanotube arrays was higher than those in back-side illuminated DSCs based on TiO2 nanotube arrays and in front-side illuminated DSCs based on TiO2 nanoparticle. Front-side illuminated DSCs based on TiO2 nanotube arrays having various thicknesses were successfully fabricated. The efficiency in DSCs having 20.0 μm thick TiO2 nanotube arrays was improved to 5.36% by TiCl4 treatment.