Novel Fabrication Method, Formation Mechanism, And Dye-Sensitized-Solar-Cells Applications Of Spherical Hierarchical Structures

Spherical hierarchical structures have attracted much attention for their unique physics and chemistry properties. However, they are usually fabricated using critical reaction conditions and they are very difficult for mass production, which restrict their applications. In this thesis, a novel and facile method for fabricating spherical hierarchical structures is proposed. Their formation mechanism and some potential applications are carefully studied.1. A novel method is proposed to fabricate spherical hierarchical structures (polyethyleneglycol (PEG) modification followed by self-assembling, PMSA). Parameters adjustment is investigated experimentally, such as PEG molecular weight and mass. Their morphologies are studied using test methods of SEM, TEM, etc. Hierarchical structures of TiO2, Fe2O3 and ZrO2 are successfully fabricated.2. The formation mechanism of spherical hierarchical structures is studied. The effect of fabrication conditions on the PEG molecular configuration is investigated. It is believed that the "lying configuration" caused by dry-grinding process is the main reason for the formation of hierarchical structures.A reasonable model is also proposed.3. Some possible applications of TiO2 spherical hierarchical structures are demonstrated. Because of their excellent light scattering property, they are used in dye-sensitized solar cell and an improved efficiency is observed. Their superior super-hydrophobic performance is also studied considering the similar surface morphology compared with lotus leaf.4. We choose TAFE method to fabricate silica A-shape wedge arrays, we can control the height and period by varying concentration of BOE solution, and we copy and transfer the microstructure into PDMS and PMMA successfully.