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Charge transport properties in nanocomposite photoanodes of DSSCs: Crucial role of electronic structure

Samadpour, M ; Sharif University of Technology

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  1. Type of Document: Article
  2. DOI: 10.1051/epjap/2011110270
  3. Abstract:
  4. TiO 2 nanorods, TiO 2 nanorod/TiO 2 nanoparticle and TiO 2 nanorod/ZnO nanoparticle composite structures were integrated as photoanodes in backside illuminated dye-sensitized solar cells (DSSCs). Incorporation of TiO 2 nanoparticles into the bare nanorods increased the dye loading and improved the short-circuit current density (J sc) from 2.22 mA/cm 2 to 3.57 mA/cm 2. ZnO nanoparticles electrochemically grown into the TiO 2 nanorod layer could increase the surface area. Nevertheless, this considerably reduced the J sc to 0.57 mA/cm 2 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 TiO 2 nanorods while the recombination rate of injected electrons to photoanode with electrolyte is near eight times faster than bare TiO 2 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
  5. Keywords:
  6. Backside-illuminated ; Cell efficiency ; Characterization methods ; Dye loading ; Dye molecule ; Dye-sensitized solar cells ; Effective diffusion coefficients ; Injected electrons ; Injection efficiency ; Lower electron density ; Nanorod layers ; Photo-anodes ; Photoanode ; Precise monitoring ; Recombination rate ; Steady state ; Structure of composites ; Surface area ; TiO ; ZnO ; ZnO nanoparticles ; Composite films ; Electrochemical impedance spectroscopy ; Electron transport properties ; Electronic structure ; Nanocomposites ; Nanoparticles ; Nanorods ; Solar cells ; Transport properties ; Zinc oxide ; Titanium dioxide
  7. Source: EPJ Applied Physics ; Volume 57, Issue 2 , February , 2012 ; 12860042 (ISSN)
  8. URL: http://www.epjap.org/articles/epjap/abs/2012/02/ap110270/ap110270.html?trendmd-shared=1