Selective Deposition of Al₂O₃ on the Upper Side-Photoelectrode to Improve Dye-Sensitized Solar Cell Efficiency

Charge recombination at the photoelectrode/dye/electrolyte interface decreases the energy conversion efficiency of dye-sensitized solar cells (DSSCs). To suppress charge recombination at this interface in DSSCs, an aluminum oxide (Al₂O₃) film can be deposited as an insulating metal oxide layer on the photoelectrode to form an energy barrier. However, the Al₂O₃ energy barrier can also disturb the transport of injected electrons to the working electrode through the titanium dioxide (TiO₂) photoelectrode. In this study, Al₂O₃ was selectively deposited as an insulating metal oxide layer on the upper side of a TiO₂ photoelectrode, which has a high probability of charge recombination, using plasma-enhanced atomic layer deposition. Deposition of the Al₂O₃ layer by this method helped to minimize the transport rate deterioration of injected electrons. This resulted in an increase of the efficiency of DSSCs containing the Al₂O₃ layer by 42.3% compared with that of a reference DSSC without the insulating metal oxide layer.