Preparation And Application Of Different TiO₂Nanostructures For Dye-sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) as one of new type solar cells with the highestphotoelectric conversion efficiency of12.3%has attracted great attention for people.Photoelectric anode material is the most important part of dye-sensitized solar cells,which directly affects the photoelectric conversion efficiency. In the thesis, we mainlystudy the impact of different TiO2nanostructures material as photoanode on theperformance of DSSCs. The main work is concentrated on the following aspects:1. We present a strategy for synthesizing TiO2nanosheets on fluorine-doped tinoxide (FTO) glass substrate through layer-by-layer absorption and reaction (LBL-AR)method using porous ZnO nanosheets as a template, followed by wet-chemicaletching and depositing process. The effect of immersing cycles on the morphology,optical property and performance of dye-sensitized solar cells (DSSCs) has beendemonstrated. A maximum efficiency of5.57%is obtained from30cycles ofimmersing, with a short-circuit current density (Jsc) of9.26mA cm-2, open-circuitvoltage (Voc) of0.835V and fill factor (FF) of72.04%. The maximum efficiencyachieved is a little higher than that of cell-P25(5.32%) and much higher than that ofZnO nanosheets (2.41%).2. Rutile TiO2nanospheres are prepared by a simple hydrolysis/condensationmethod at low temperature using1,2-propylene glycol as the retardation agent. Adouble layered structure consisting of rutile TiO2nanospheres as overlayer andanatase TiO2nanocrystals as underlayer is designed for the photoanode indye-sensitized solar cells (DSSCs). It can be found that the double layered film cellreaches up the maximum conversion efficiency of7.86%, which is much higher thanthat of P25film cell (η=6.90%) under identical film thickness. The enhancedefficiency of the double layered film cell is mainly attributed to the enhanced lightharvesting and dye loading of rutile TiO2nanospheres.3. Hierarchical TiO2nanotubes arrays on the Ti plate are successfully prepared byanodic oxidation and hydrothermal method. The hierarchical nanostructures with theTiO2nanotubes trunk and nanowires branches have higher specific surface areas and stronger light scattering ability than that of common TiO2nanotubes, which is moreadvantageous for the electronic transmission, leading to the maximum photoelectricefficiency of4.22%.