Title: Characterisations and DSSC efficiency test of TiO2 nano-films formed by filtered cathodic vacuum arc deposition

Authors: C. Aramwit; L.D. Yu; L. Gregoratti; S. Choopun; S. Intarasiri; D. Bootkul; U. Tippawan

Addresses: Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand ' Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand; Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok, 10400, Thailand ' Elettra – Sincrotrone Trieste ScPA, Area Science Park, SS14-Km163.5, Basovizza-Trieste, 34149, Italy ' Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand ' Science and Technology Research Institute, Chiang Mai University, Chiang Mai, 50200, Thailand ' Departments of General Science, Faculty of Science, Srinakharinwirot University, Bangkok, 10110, Thailand ' Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand

Abstract: For photovoltaic applications in dye-sensitised solar cells (DSSC), used as a wide band semiconductor layer, titanium dioxide (TiO2) nano-films were formed by the filtered cathodic vacuum arc deposition (FCVAD) technique using Ti as the cathode and controlled oxygen (O2) gas inlet under varied deposition and post-deposition annealing conditions. The deposition conditions included the O2 pressure as the key parameter and others such as deposition time and bias. The work was aimed at investigating the FCVAD condition effect on the TiO2 film characteristics and thus the solar cell efficiency. The formed films were characterised using optical microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy and scanning photoemission microscopy (SPEM) techniques. All the characterisations revealed that the film transparency increased and thickness decreased to a nanoscale with increasing of the O2 pressure, the transparent deposited films contained stoichiometric titanium and oxygen under the medium O2 pressure, the as-deposited films were TiO2 containing some rutile but without anatase, and the annealing improved the film quality by introducing anatase and increasing the Ti-oxide. Test of the films for the DSSC-photovoltaic property efficiency showed that the efficiency of using the annealed films was 104 times that of using the as-deposited films, indicating the crucial significance of the anatase.

Keywords: filtered cathodic VAD; FCVAD; vacuum arc deposition; titanium dioxide; oxygen pressure; anatase; dye-sensitised solar cells; DSSC efficiency; TiO2 nanofilms; nanotechnology; photovoltaics; annealing.

DOI: 10.1504/IJNT.2017.082383

International Journal of Nanotechnology, 2017 Vol.14 No.1/2/3/4/5/6, pp.481 - 495

Published online: 21 Feb 2017 *

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