Preparation of titania with different morphologies and its application in dye-sensitized solar cell

• Main Authors: Lin, Chien-Chih, 林建志
• Other Authors: Chien, Wen-Chen
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/13174234433063836713

碩士 === 明志科技大學 === 化學工程研究所 === 99 === In this Study, the preparation of different morphologies titanium dioxide (TiO2) and its application for preparing a dye-sensitized solar cells (DSSCs) with a high performance was investigated. The main research items in this study include：（1）Preparation of the primary titanium dioxide particles with different morphologies from commercial product P25 by applying the basic chemical reaction and hydrothermal process;（2）Preparation of the secondary titanium dioxide aggregates with different aggregate structures by the spray drying;（3）Preparation of titanium dioxide photoelectrode by using the blade coating method and the investigation on the effects of different TiO2 morphologies, substrates, coating layers, and mixed ratios of various titanium dioxide on the photoelectric conversion efficiency of battery. The commercial titanium dioxide P25 as the precursor was firstly reacted with sodium hydroxide in the hydrothermal condition and then washing with dilute HCl and distilled water, and spray drying to obtain the white titanium dioxide powders with different morphologies. The prepared titanium dioxide powders were characterized by the transmission electron microscopy (TEM), scanning electron microscopy (SEM) and high-resolution field emission scanning electron microscopy (FE-SEM) for the particle size and shape, X-ray diffraction (XRD) for the crystalline phase, specific surface area analyzer (BET) for the surface area analysis, and incident electron conversion efficiency (IPCE) for the efficiency of the photoelectrode at different wavelengths, respectively. Moreover, the TiO2 photoelectrode and the corresponding platinum electrode, and electrolyte was assembled into the dye-sensitized solar cells. The open circuit voltage (Voc), short circuit current (Jsc), interface resistance, fill factor (FF), and the photoelectric conversion efficiency (η) of the cells was measured at a solar simulation condition (AM1.5, 1000 W/m2). The results show that three different morphologies of titanium dioxide were successfully prepared at various hydrothermal conditions: TiO2 nanotubes (140℃ and 24h), TiO2 nanorods (180℃ and 24h), and TiO2 nanowires (180℃ and 72h). Then, four different morphologies of titanium dioxide powders were obtained from the prepared TiO2 through the spray drying. The as-prepared TiO2 has a weak crystalline structure. High crystalline powders with a pure anatase or anatase/rutile mixed powders could be obtained after the calcination process. The photoelectric conversion efficiency (η) of the dye-sensitized solar cells prepared from different morphologies of titanium dioxide decreases in the following order: P25> spray drying TiO2 (SP25)> TiO2 nanowires (NW)> TiO2 nanotubes (NT)> TiO2 nanorods (NR)> spray drying TiO2 nanorods (SNR)> spray drying TiO2 nanowires (SNW). Further, theηof cells with FTO substrate is larger than that obtained with ITO substrate. Theηof cells wit double-layer TiO2 is also larger than that obtained with single-layer. The different packaging method (Surlyn packaging, Surlyn + UV plastic package) has no significant effect on the photoelectric conversion efficiency. The TiO2 films prepared from the wet-ground TiO2 slurry have a better planarity than those obtained from agitated TiO2 slurry. No cracks of films are observed. Finally, the results obtained from various ratios of NW TiO2/P25 cells show that 2.5% of the NW-doped paste produces a best cell performance: Voc=0.75(V), Jsc=12.10(mA/cm2), FF=0.65, η=5.88(%). IPCE measurement also indicates that 2.5% of the NW-doped paste has a best photoelectric conversion efficiency of 58.1% under 540nm wavelength.