Preparation Of TiO₂ Nanowires And Their Application In Dye-Sensitized Solar Cell And Photocatalysis

Dye-sensitized solar cells （DSSCs） have attracted considerable attention from many research institutes, due to their low cost, facile fabrication process,relatively high conversion efficiency and lower sensitivity to light angle of incidence compared to the conventional silicon solar cells. The heart of the DSSCS is the mesoporous semiconductor electrodes, but the photoanode material of conventional DSSC was porous TiO₂ nanoparticles thin film. Because there is a higher rate of grain boundaries and defect between nanoparticles, the recombination of electrons often occurs in those place resulting in a lower charge collection efficiency, TiO₂ nanowires can provide direct conduction pathways of photogenerated electrons and reduce the defects of grain boundaries, thus resulting in reducing the recombination of electrons, therefore it is very important for the DSSCs. This thesis, we focus on the fabrication of TiO₂ nanowires and their applications in DSSCs. The main contents are as follows:1. In order to study the one-dimensional （1D） nanomaterials applications in DSSCs, and improve the efficiency of the DSSCs which base on the one-dimensional nanomaterials. We optimize the conventional craft of the DSSCS.2. In the non-polar solvent / hydrophilic substrate interfacial reaction, we successfully synthesize hierarchical TiO₂ nanostructures consisting of nanowire, and its growth mechanism was discussed. Because of the hierarchical TiO₂ nanostructures possessing the advantages of the fast electron transport, light scattering effect and large surface area, the DSSCs consisting of nanoparticles and the hierarchical TiO₂ nanostructures achieve the energy conversion efficiency up to 8.54%. The relation between photocatalytic properties and synthesized temperature of hierarchical TiO₂ nanostructures was also discussed.3. Here we present a substrate-free, large area, continuous oriented single-crystal rutile TiO₂ nanowires array films which the thickness can be controlled in the range of 10-80μm with the reaction temperature. The length and the diameter of the nanowires could be tuned by changing the growth parameters, such as growth temperature and growth time. The oriented single-crystal TiO₂ nanowires array films show excellent photoluminescence and higher photocatalytic degradation efficiency than polycrystalline TiO₂ nanowires film due to their well crystalline structure.