The Morphology Control Of TiO₂ And The Performance Research Of Dye-sensitized Solar Cell

Nowadays all countries have to face two serious problems: energy crisis and environmental pollution. As a result, research and development of new energy attract researchers’ interests. Among the varied new energies, solar energy is an attractive topic because it is inexhaustible and environmentally friendly. And dye-sensitized solar cells(DSSCs) have advantages of low cost, simple synthesis process, excellent stability, high theoretical energy conversion efficiency. Photoanode is the core of the DSSCs, which directly determines the transportation, transmission and collection of photogenerated electrons and dye absorption. In this thesis, the Ti O2 nanomaterials with different nanostructures and morphologies were controllably prepared. The influence of the different nanostructures and morphologies on the performance of their DSSCs were investigated.(1) Due to offering a direct conduction pathway and fast electron transport, 1D nanostructures play an important role in improving charge collection efficiency in dyesensitized solar cells(DSSCs). The anatase Ti O2 nanorods with different aspect ratios between 3.2 and 6.3 were obtained by controlling reaction time for DSSCs. As their aspect ratios increased, more dye was adsorbed on the anatase Ti O2 nanorods film. A promising power conversion efficiency of 7.51% was obtained for the anatase Ti O2 nanorods with the biggest aspect ratio of 6.3.(2)TBAH and CTAB were used as surfactants to control crystal facets and morphologies of Ti O2, respectively. The morphology and structure of the samples were controlled by the mass ratio of CTAB/TBAH. Self-branching anatase Ti O2 nanorods were obtained. Although the obtained nanostructures didn’t improve the dye absorption obviously, the multiple branching nanorods offered more electrons transmission pathways. In addition, this novel structure improved the ability of electrons transport, resulting in increase of Jsc of DSSCs. Higher photovoltaic conversion efficiency(7.51%) has been obtained than that of P25 Ti O2, showing 24.5% increase.(3) One-step hydrothermal method was employed to construct nanorods-based Ti O2 nanoflowers by using PEI as medium of morphology control and controlling the reaction times. With the increase of the reaction time, intermediate products had disappeared and morphology of final products was uniform. The sample obtained for 70 h showed the biggest specific surface area and the ability of light scattering. The power conversion efficiency of the device based on the nanorods-based Ti O2 nanoflowers prepared for 70 h could be up to 7.29%, superior to that of the devices based on the nanorods-based Ti O2 nanoflowers prepared for 12 h, indicating 86.4% in η.