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Efficient Performance of Electrostatic Spray-Deposited TiO 2 Blocking Layers in Dye-Sensitized Solar Cells after Swift Heavy Ion Beam Irradiation

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ABSTRACT

A compact TiO2 layer (~1.1 μm) prepared by electrostatic spray deposition (ESD) and swift heavy ion beam (SHI) irradiation using oxygen ions onto a fluorinated tin oxide (FTO) conducting substrate showed enhancement of photovoltaic performance in dye-sensitized solar cells (DSSCs). The short circuit current density (Jsc = 12.2 mA cm-2) of DSSCs was found to increase significantly when an ESD technique was applied for fabrication of the TiO2 blocking layer, compared to a conventional spin-coated layer (Jsc = 8.9 mA cm-2). When SHI irradiation of oxygen ions of fluence 1 × 1013 ions/cm2 was carried out on the ESD TiO2, it was found that the energy conversion efficiency improved mainly due to the increase in open circuit voltage of DSSCs. This increased energy conversion efficiency seems to be associated with improved electronic energy transfer by increasing the densification of the blocking layer and improving the adhesion between the blocking layer and the FTO substrate. The adhesion results from instantaneous local melting of the TiO2 particles. An increase in the electron transport from the blocking layer may also retard the electron recombination process due to the oxidized species present in the electrolyte. These findings from novel treatments using ESD and SHI irradiation techniques may provide a new tool to improve the photovoltaic performance of DSSCs.

No MeSH data available.


Nyquist spectra (measured under light illumination (100 mW cm-2)) of DSSCs. The inset represents the impedance spectra expanded in the high frequency ranges. The scattered points are experimental data, and the solid lines are the fitting curves.
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Figure 7: Nyquist spectra (measured under light illumination (100 mW cm-2)) of DSSCs. The inset represents the impedance spectra expanded in the high frequency ranges. The scattered points are experimental data, and the solid lines are the fitting curves.

Mentions: Electrochemical impedance spectroscopy (EIS) provides valuable information on the kinetics of electron transport in the DSSCs with deeper understanding of the interfacial reactions at FTO/TiO2 [33] and therefore was employed to decipher the blocking layer effect in DSSCs. Figure 7 shows the Nyquist plots of the electrochemical impedance spectra. Their equivalent circuit is given as an inset in the figure. The charge transfer resistances RCT1 and RCT2 represent the resistances at the Pt/FTO and TiO2/dye/electrolyte interfaces, respectively. The electrochemical parameters were estimated by fitting experimental data with the equivalent circuit (inset of Figure 7) [34] and are summarized in Table 2.


Efficient Performance of Electrostatic Spray-Deposited TiO 2 Blocking Layers in Dye-Sensitized Solar Cells after Swift Heavy Ion Beam Irradiation
Nyquist spectra (measured under light illumination (100 mW cm-2)) of DSSCs. The inset represents the impedance spectra expanded in the high frequency ranges. The scattered points are experimental data, and the solid lines are the fitting curves.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211366&req=5

Figure 7: Nyquist spectra (measured under light illumination (100 mW cm-2)) of DSSCs. The inset represents the impedance spectra expanded in the high frequency ranges. The scattered points are experimental data, and the solid lines are the fitting curves.
Mentions: Electrochemical impedance spectroscopy (EIS) provides valuable information on the kinetics of electron transport in the DSSCs with deeper understanding of the interfacial reactions at FTO/TiO2 [33] and therefore was employed to decipher the blocking layer effect in DSSCs. Figure 7 shows the Nyquist plots of the electrochemical impedance spectra. Their equivalent circuit is given as an inset in the figure. The charge transfer resistances RCT1 and RCT2 represent the resistances at the Pt/FTO and TiO2/dye/electrolyte interfaces, respectively. The electrochemical parameters were estimated by fitting experimental data with the equivalent circuit (inset of Figure 7) [34] and are summarized in Table 2.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

A compact TiO2 layer (~1.1 μm) prepared by electrostatic spray deposition (ESD) and swift heavy ion beam (SHI) irradiation using oxygen ions onto a fluorinated tin oxide (FTO) conducting substrate showed enhancement of photovoltaic performance in dye-sensitized solar cells (DSSCs). The short circuit current density (Jsc = 12.2 mA cm-2) of DSSCs was found to increase significantly when an ESD technique was applied for fabrication of the TiO2 blocking layer, compared to a conventional spin-coated layer (Jsc = 8.9 mA cm-2). When SHI irradiation of oxygen ions of fluence 1 × 1013 ions/cm2 was carried out on the ESD TiO2, it was found that the energy conversion efficiency improved mainly due to the increase in open circuit voltage of DSSCs. This increased energy conversion efficiency seems to be associated with improved electronic energy transfer by increasing the densification of the blocking layer and improving the adhesion between the blocking layer and the FTO substrate. The adhesion results from instantaneous local melting of the TiO2 particles. An increase in the electron transport from the blocking layer may also retard the electron recombination process due to the oxidized species present in the electrolyte. These findings from novel treatments using ESD and SHI irradiation techniques may provide a new tool to improve the photovoltaic performance of DSSCs.

No MeSH data available.