Eur. Phys. J. Appl. Phys.
Volume 57, Number 2, February 2012
|Number of page(s)||7|
|Section||Nanomaterials and Nanotechnologies|
|Published online||23 December 2011|
Charge transport properties in nanocomposite photoanodes of DSSCs: crucial role of electronic structure
Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 11155-8639, Tehran, Islamic Republic of Iran
2 Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran, Islamic Republic of Iran
3 Department of Physics, Faculty of Sciences, Arak University, Arak 38156-8-8349, Islamic Republic of Iran
a email: email@example.com
Revised: 30 September 2011
Accepted: 3 November 2011
Published online: 23 December 2011
TiO2 nanorods, TiO2 nanorod/TiO2 nanoparticle and TiO2 nanorod/ZnO nanoparticle composite structures were integrated as photoanodes in backside illuminated dye-sensitized solar cells (DSSCs). Incorporation of TiO2 nanoparticles into the bare nanorods increased the dye loading and improved the short-circuit current density (Jsc) from 2.22 mA/cm2 to 3.57 mA/cm2. ZnO nanoparticles electrochemically grown into the TiO2 nanorod layer could increase the surface area. Nevertheless, this considerably reduced the Jsc to 0.57 mA/cm2 and consequently cell efficiency. Electrochemical impedance spectroscopy (EIS) results showed that ZnO incorporated samples have better effective diffusion coefficient of electrons in comparison with bare TiO2 nanorods while the recombination rate of injected electrons to photoanode with electrolyte is near eight times faster than bare TiO2 nanorods. ZnO incorporated samples showed lower electron density at steady state in the conduction band also. The worse performance of ZnO incorporated samples was attributed to lower electron injection efficiency from excited dye molecules. Monitoring electron transport properties of the cells measured by EIS pointed out the crucial role of electronic structure of composite film components on the performance of cells. Our results showed that EIS technique could be used as an efficient characterization method for precise monitoring of charge transport in nanocomposite photoanodes for DSSCs.
© EDP Sciences, 2011
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