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Browsing by Author "Santos, M.P. dos"

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  • A detailed study on the Fe-doped TiO 2 thin films induced by pulsed laser deposition route
    Publication . Meng, Lijian; Wang, Zhenhua; Yang, Liang; Ren, Weijun; Liu, Wei; Zhang, Zhidong; Yang, Tao; Santos, M.P. dos
    Fe-doped TiO2 thin films are deposited both on the (100) oriented Si and glass substrates by pulsed laser deposition technique using Fe powder doped TiO2 ceramic target. The structural and optical properties of the film have been studied in detail. The degree of film crystallinity is investigated by X-ray diffraction and confirmed by Raman scattering measurements. The stoichiometry and chemical states of Fe, Ti and O are probed by X-ray photoelectron spectroscopy. The surface morphologies are observed by Scanning electron microscopy. The optical properties are studied by measuring the transmittance and the optical constants, the refractive index and the extinction coefficient. It is found that the substrate temperature is a key factor in determining the thin film structure which further influences the refractive index and the optical band gap of the film. An anatase structure emerges above 300 ºC while the rutile structure appears when the substrate temperature is higher than 500 ºC. Another result is that Fe exists in the deposited films as Fe3+ and the atomic concentration of Fe in the films is much lower than that in the source target.
    2018Journal article Restricted access Show more
  • Preparation and characterization of dye-sensitized TiO2 nanorod solar cells
    Publication . Meng, Lijian; Chen, Hong; Li, Can; Santos, M.P. dos
    TiO2 nanorodswere prepared by DC reactive magnetron sputtering technique and applied to dye-sensitized solar cells (DSSCs). The length of the TiO2 nanorods was varied from 1 μm to 6 μm. The scanning electronmicroscopy images showthat the nanorods are perpendicular to the substrate. Both the X-ray diffraction patterns and Raman scattering results show that the nanorods have an anatase phase; no other phase has been observed. (101) and the (220) diffraction peaks have been observed for the TiO2 nanorods. The (101) diffraction peak intensity remained constant despite the increase of nanorod length, while the intensity of the (220) diffraction peak increased almost linearly with the nanorod length. These nanorods were used as the working electrodes in DSSCs and the effect of the nanorod length on the conversion efficiency has been studied. An optimumphotoelectric conversion efficiency of 4.8% has been achieved for 4 μm length nanorods.
    2015-02-27Journal article Restricted access Show more