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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.

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J-V measurements under a light illumination (100 mW cm-2) along with b dark condition (lower part of the spectrum).
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Figure 6: J-V measurements under a light illumination (100 mW cm-2) along with b dark condition (lower part of the spectrum).

Mentions: Figure 6 shows the photocurrent density–voltage (J-V) characteristics measured under 1 sun (100 mW cm-2 AM 1.5) and dark conditions. The photovoltaic parameters were estimated from Figure 6 and are summarized in Table 1. The photocurrent density (Jsc) was increased from 8.9 to 12.2 mA cm-2, and the overall efficiency (η) was markedly improved from 3.8 to 5.1% by replacing the ESD TiO2 compact layer, compared to the conventionally spin-coated blocking layer. This might be attributed to the highly compact nature of the ESD films, which provide more effective pathways for electrons. As a result, electrons can be collected faster at the TCO and transferred to the external circuit, resulting in improvement in the photovoltaic performance. However, there is no appreciable change in the open circuit voltage (Voc) between these samples. When the ESD cell was treated with SHI irradiation, the open circuit voltage was further improved from 0.60 to 0.63 V, and consequently, the overall energy conversion efficiency improved from 5.1 to 5.5%. This may be because of the SHI irradiation, which melted TiO2 particles and thereby improved electrical contact with the FTO substrate (denser and more compact) and among TiO2 particles. This clearly demonstrates that the SHI irradiation enhances the blocking effect of electron recombination and creates a facilitating effect on electron transport.


Efficient Performance of Electrostatic Spray-Deposited TiO 2 Blocking Layers in Dye-Sensitized Solar Cells after Swift Heavy Ion Beam Irradiation
J-V measurements under a light illumination (100 mW cm-2) along with b dark condition (lower part of the spectrum).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: J-V measurements under a light illumination (100 mW cm-2) along with b dark condition (lower part of the spectrum).
Mentions: Figure 6 shows the photocurrent density–voltage (J-V) characteristics measured under 1 sun (100 mW cm-2 AM 1.5) and dark conditions. The photovoltaic parameters were estimated from Figure 6 and are summarized in Table 1. The photocurrent density (Jsc) was increased from 8.9 to 12.2 mA cm-2, and the overall efficiency (η) was markedly improved from 3.8 to 5.1% by replacing the ESD TiO2 compact layer, compared to the conventionally spin-coated blocking layer. This might be attributed to the highly compact nature of the ESD films, which provide more effective pathways for electrons. As a result, electrons can be collected faster at the TCO and transferred to the external circuit, resulting in improvement in the photovoltaic performance. However, there is no appreciable change in the open circuit voltage (Voc) between these samples. When the ESD cell was treated with SHI irradiation, the open circuit voltage was further improved from 0.60 to 0.63 V, and consequently, the overall energy conversion efficiency improved from 5.1 to 5.5%. This may be because of the SHI irradiation, which melted TiO2 particles and thereby improved electrical contact with the FTO substrate (denser and more compact) and among TiO2 particles. This clearly demonstrates that the SHI irradiation enhances the blocking effect of electron recombination and creates a facilitating effect on electron transport.

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.


Related in: MedlinePlus