Assembly of highly ordered three-dimensional porous structure with nanocrystalline TiO2 semiconductors

In this paper, we report on the assembly of a highly ordered three-dimensional porous structure with nanosized crystalline TiO2 particles by a cooperative assembly method in which the fabrication of the template and the infiltration of the voids of the template are carried out at the same time and the related experimental parameters for the assembly, including temperature, humidity, and concentrations and concentration ratio of the colloid mixture. SEM (scanning electron microscope) images and transmission spectra of these samples demonstrate that these films have a highly ordered three-dimensional structure. The Bragg law was used to calculate the diameter of the spheres of air in the porous TiO2 structure. A good agreement between the calculated results for the diameter of the spheres of air and those measured by SEM further confirms the high quality of the films fabricated using this simple method. Additionally, based on these experimental results, a detailed mechanism of the simple method is also discussed.