Efficient Performance of Electrostatic Spray-Deposited TiO2 Blocking Layers in Dye-Sensitized Solar Cells after Swift Heavy Ion Beam Irradiation.

P Sudhagar,June Hyuk Jung,Yong-Gun Lee,K Asokan,Yong Soo Kang,Suil Park

doi:10.1007/s11671-010-9763-2

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.

Highlights

Dye-sensitized solar cells (DSSCs) are a promising photovoltaic system for generation solar cells that contain mesoporous nanocrystalline semiconductors like TiO2, ZnO and SnO2 as photoanodes anchored with dye molecules
The increase in the relative peak intensities observed in the swift heavy ion beam (SHI)-irradiated sample shows that the SHI irradiation induced crystallization when compared to the as-prepared pristine electrostatic spray deposition (ESD) TiO2 films
The results described above suggest that contact among nanoparticles and the adhesion properties of a blocking layer with an fluorinated tin oxide (FTO) substrate may improve the performance of dye-sensitized solar cells

Summary

Introduction

Dye-sensitized solar cells (DSSCs) are a promising photovoltaic system for generation solar cells that contain mesoporous nanocrystalline semiconductors like TiO2, ZnO and SnO2 as photoanodes anchored with dye molecules. Zhang et al [19] demonstrated the feasibility of ESD-derived uniform TiO2 particles in DSSCs and suggested that the electrical contact between the conducting substrate and TiO2 particle (electron transport layer) plays a crucial role in power conversion efficiency, since the presence and the removal of the polymer molecules in the ESD layer during sintering may result in poor contact among TiO2 nanoparticles and poor adhesion to conductive glass substrates. These will impose severe constraints on the electron transport from the mesoporous TiO2 layer to the FTO substrate. The conductivity of the samples was studied via the twoprobe method

Results and Discussion

Conclusions

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