Performance Enhancement of Dye-Sensitized Solar Cells by MgO Coating on TiO2 Electrodes

TiO2/MgO composite films were prepared by coating the magnesium acetate solution in the pores of mesoporous TiO2 films using a dip coating method. Concentrations of magnesium acetate solution were varied in a range of 1x10-4 – 1x10-1 M. The TiO2/MgO composite films were characterized by scanning electron microscopy (SEM), transmission electron microscropy (TEM), electrochemical impedance spectroscopy(EIS) , transient voltage decay and I-V test. The TiO2 films and TiO2/MgO composite films were immersed in a 0.3 mM N719 dye solution. The Dye-sensitized solar cells with the TiO2/MgO/N719 structure showed an optimal concentration of magnesium acetate solution of 1x10-3 M resulting in the MgO film estimated thickness of 0.0963 nm and giving the maximum efficiency of 4.85%. The improved efficiency of dyesensitized solar cell was due to the magnesium oxide film as the wide band gap coating decays the electron back transfer to the triiodide electrolyte and reduce charge recombination.

Authors:

• C. Photiphitak
• P. Rakkwamsuk
• P. Muthitamongkol
• C. Thanachayanont

Keywords:

• Magnesium oxide thin film
• TiO2/MgO composite films
• Electrochemical Impedance Spectrum
• Transient voltage decay

References:

[1] B. O'Regan, M. Grätzel, "A low-cost, high-efficiency solar cell based on
dye- sensitized colloidal TiO2 films," Nature, vol. 353, no. 6346, pp.
737-740, 1991
[2] D.S. Tsoukleris, I.M. Arabatzis, E.Chatzivasiloglou, A.I. Kontos, V.
Belessi, M.C. Bernard, P. Falaras, "2-Ethyl-1-hexanol based screenprinted
titania thin films for dye-sensitized solar cells," Solar Energy,
vol. 79, pp. 422-430, 2005.
[3] C.O. Avellaneda, A.D. Goncalves, J.E. Benedetti, A.F. Nogueira,
"Preparation and characterization of core-shell electrodes for application
in gel electrolyte-base dye-sensitized solar cells," Electrochimica Acta,
vol. 55, pp. 1468 - 1474, 2010.
[4] Z. Liu, K. Pan, M.Lui, M. Wang, Q. Lu, J. Li, Y. Bai, T. Li, "Al2O3-
coated SnO2/TiO2 composite electrode for the dye-sensitized solar cell,"
Electrochimica Acta, vol. 50, pp. 2583 - 1474, 2589.
[5] J. Bandara, S.S. Kuruppu, U.W. Pradeep, " The promoting effect of
MgO layer in sensitized photodegradation of colorants on TiO2/MgO
composited oxide," Colloids and Surfaces A: Physicochem. Eng.
Aspects, vol 276, pp. 197 - 202, 2006.
[6] G.R.A. Kumara, M. Okuya, K. Murakami, S. Kaneko, V.V. Jayaweera,
K. Tennakone, "Dye-sensitized solid-state solar cells made from
magnesiumoxide-coated nanocrystalline titanium dioxide films:
enhancement of the efficiency," Journal of Photochemistry and
Photobiology A: Chemistry, vol. 164, pp. 183-185, 2004.
[7] C. Photiphitak, P. Rakkwamsuk, P. Muthitamongkol, C. Sae-Kung, C.
Thanachayanont, "Effect of Silver Nanoparticle Size on Efficiency
Enhancement of Dye-Sensitized Solar Cells," International Journal of
Photoenergy, vol. 2011, Article ID 258635, pp.1-8, 2011.
[8] K. Che Lee, S. Jein Lin, C. Hong Lin, C. Song Tsai, Y. Jen Lu, "Size
effect of Ag nanoparticles on surface plasmon resonance", Surf Coat
Tech, vol. 202, pp. 5339-5342,Aug 2008.
[9] B. Evgenij, M.J. Ross, "Impedance spectroscopy theory, experiment,
and applications," New Jersy : Wiley, 2005.
[10] L. Han, N. Koide, Y. Chiba, A. Islam, T. Mitate, "Modeling of an
equivalent circuit for dye-sensitized solar cells: improvement of
efficiency of dye-sensitized solar cells by reducing internal resistance,"
C.R. Chimie, vol.9, pp. 645 - 651, 2006.
[11] J. Bandara, R.A.S.S. Ranasinghe, "The effect of MgO coating on
photocatalytic activity of SnO2 for the degradation of chlorophenol and
textile colorant ; the correlation between the photocatalytic activity and
the negative shift of flatband potential of SnO2," Applied Catalysis A:
General, vol. 319, pp. 58-63, 2007
[12] J. Bandara, S.S. Kuruppu, U.W. Pradeep, "The promoting effect of
MgO layer in sensitized photodegradation of colorants on TiO2/MgO
composite oxide, "Colloids and Surfaces A: Physicochem. Eng. Aspects,
vol. 276, pp. 197 - 202, 2006.