Study On Preparation, Properties Of TiO₂Nanorods Array And Its Application In Dye Sensitized Solar Cells

TiO₂has become the research hotspot due to its rich resources, security, non-toxic,stable chemical properties. One-dimensional （1-D） TiO₂including nanorod andnanowire have attracted much attention since TiO₂nanowire/nanorod have good surfaceroughness and photoelectric property. So TiO₂nanowire/nanorod have a wide range ofapplications in many ways，such as self-cleaning, antifouling, hydrophobicity, inhibitingthe surface corrosion and dye-sensitized solar cells （DSSCs）. So it is necessary to carrayon the systematic study.In this paper, on one hand, TiO₂nanorod arrays （NRAs） with tunable surfacemorphologies were prepared in different HCl concentration solutions by hydrothermalmethod on fluorine-doped tin oxide coated glass substrates. The properties of thesenanostructures were characterized by XRD, SEM and XPS. TiO₂NRAs exhibit a highwater contact angle （WCA） after hydrophobic treatment. Baded on the results, weanalyzed the factors of HCl concentration and hydrophobic agents which influence thehydrophobic performance of TiO₂NRAs.On the other hand, high orientation of TiO₂NRAs were prepared on seededsubstrate by combination of sol-gel and hydrothermal synthesis method and theproperties of these nanostructures were characterized by XRD, SEM andultraviolet-visible spectrophotometer. The affect of seed layers on the structure,morphology and dye adsorption amount of TiO₂NRAs were studied. The properties ofthe DSSCs based on TiO₂NRAs with and without seed layers were investigated bycurrent-voltage characteristics. In addition, we studied the effect of seed layer on the theperformance of dye-sensitized solar cells. The main results are as following:①Rutile TiO₂NRAs were prepared in different HCl concentration solution byhydrothermal method on FTO substrate and characterized by XRD, SEM and XPS. Weanalyzed the influence of HCl concentration on the morphology and roughness of TiO₂NRAs. The results show that the higher the concentration of HCl, the more cluttered andmore rough of TiO₂NRAs.②When the film prepared with7.0M HCl and modified with triethoxyoctylsilane,TiO₂NRAs exhibits a high WCA of157.3±1.5o with the advancing contact angle of154.2±1.3o and receding contact angle of161.2±1.3o and a small sliding angle of7o.The Cassie theory was used to analyze the hydrophobic phenomenon of the as-prepared film, and it reveals that only about9%of the water surface is contacted with the TiO₂film and the rest91%is contacted with the air cushion, which is reasonable for thehydrophobicity of TiO₂nanorod film.③Rutile TiO₂NRAs were prepared on FTO substrate with seed layers bycombination of sol-gel and hydrothermal synthesis method. TiO₂NRAs are verticallyoriented and evenly distributed, the length about1.7μm. The results show that TiO₂NRAs with seed layers are more even, denser and better oriented than that without seedlayers. Typically, the average diameters of TiO₂NRAs which derived from TTIP in therange of0.005⁰.05M are about35nm, and they are more uniform and better separatedfrom each other than those grown without seed layers （average diameter35⁸5nm）.④The photoelectric conversion efficiency of DSSCs based on seeded TiO₂NRAsis larger than that without seed layers. With the increase of TTIP concentration, thephotoelectric conversion efficiency, open circuit voltage, fill factor and short circuitcurrent of DSSCs are larger before they are reduced. Typically, the energy efficiency ofDSSCs obtained from seed solution of0.025M TTIP is1.47%, about1.8times greaterthan that without seed layers. The performance improvement is attributed to the fact thatthe thinner, denser and better oriented NRAs grown on seeded substrate absorb moredye and make for suppressing charge recombination at the FTO substrate/electrolyteinterface.