Preparation And Application Of TiO₂ Nanorods For Dye Sensitized Solar Cells

Dye-sensitized solar cell(DSSC) is a new type of solar cell and known as a powerful alternative for the traditional silicon solar cell due to its low cost, simple preparation process and long operation lifetime, the improvement of photo-electric conversion efficiency is the focus of the current study. As the critical materials, it has been generally accepted that the photovoltaic performance of DSSC is highly dependent on the morphological and structural characteristics of the photoanode. Traditional Ti O2 nanoparticles(NPs) with high specific surface area have large amount of boundaries between nanoparticles which lead to the electron-hole recombination centers, thereby lowering the efficiency of DSSC. One-dimensional(1-D) nanostructure is favored for fast electron transport and high light-scattering effect which can be used to improve the photo-electron conversion efficiency of DSSCs. Hence, we propose a simple hydrothermal method to prepare the1-D nanorods and discuss the application in DSSCs at the same Time. The main research contents include:(1) The oriented 1-D Ti O2 nanorod arrays were fabricated directly on FTO coated glass via a hydrothermal method. The influence of substrate, hydrochloric acid and precursors on the growth of nanorods was investigated via changing the hydrothermal conditions to discuss the mechanism of growth. The results show that the nanorods are of 1-D single crystal rutile structure with growth direction along the(110) crystal planes and perpendicular to the substrate by step edge. FTO substrate and hydrochloric are both essential for the epitaxy growth of nanorods.(2) The diameter, thickness of the nanorods can be adjusted by changing hydrothermal time, temperature and the precursor amounts. After TiCl4 treatment, different thicknesses of nanorod arrays were assembled DSSCs and tested photo-electron performance. The results indicate that DSSC with 3 ?m nanorod array obtains the highest conversion efficiency.(3) The composite photoanode of TiO2 nanorods/nanopartciles(NR+NP) were fabricated by screen-printing TiO2 nanopartciles on as-synthesized Ti O2 nanorod arrays. For comparison, Ti O2 nanorods photoanode(NR) and TiO2 nanopartciles photoanode(NP) of same thickness were also prepared. Three kinds of photoanodes were assembled DSSCs and performed. And the results indicate that the NR+NP cell exhibits superior conversion efficiency of 4.57% for the advantages of large surface area of nanopartciles. More importantly, the 1-D nanorods in NR+NP can offer faster electron transport, superior electron recombination restraint characteristics and high light scattering effect.