Structural, morphological, and optical analysis of TiO2 inverse opals prepared under different synthesis conditions

Abstract

Although TiO2 inverse opals have been used in different applications for the last decades, controlling their properties is still a matter of effort. In this paper, it is shown that the structure, morphology, and optical properties of TiO2 inverse opals can be precisely controlled by changing the synthesis conditions. Herein, TiO2 inverse opals were synthesized using the sol-gel method. First of all, opal photonic crystals were fabricated by monodisperse poly (methyl methacrylate) (PMMA) microspheres using the self-assembly-based vertical deposition technique. Then, the TiO2 precursor was synthesized by mixing ethanol, HCl, and selected ratios of titanium tetra isopropoxide (TTIP). Furthermore, four different amounts of the precursor were injected into the opal structures. The conditions for fabricating the most crack-free and uniform structures on a micro-scale were discussed. Also, the penetration rate, the thickness of the structure, its porosity, and photonic bandgap (PBG) qualities were investigated for different synthesized conditions. It has been believed that the results of this study can be beneficial for different TiO2 inverse opal applications to choose the best synthesizing conditions for the desired aim.