Electrochimica Acta, Vol.179, 197-205, 2015
Directly grown anatase TiO2 films via liquid phase deposition as the photoanodes for dye-sensitized solar cells
Anatase TiO2 films were directly grown on the conductive glass by liquid phase deposition (LPD) and used as the photoanodes of dye-sensitized solar cells (DSSCs). TiO2 films deposited at a higher temperature had a wider pore size distribution and a perfectly interfacial binding with the conductive FTO layer, while the ones deposited at a lower temperature presented a higher specific surface area to adsorb more dye so that the DSSCs with such two-temperature deposited gradient TiO2 films had the enhanced performance significantly. Moreover, deposition at 80 degrees C showed a higher deposition rate and TiO2 in the derived films was in a large crystallite size as well as a larger particle size, but a longer duration resulted in some single-crystal particles through the dissolving-precipitation mechanism, which were not suitable to the photoanodes. Thus, gradient TiO2 films were firstly deposited at 80 degrees C and subsequently at 60 degrees C for a varying duration to efficiently tune their thickness. The DSSCs with the gradient TiO2 film photoanodes presented a short-circuit current density of 14.9 mA cm 2 and an energy conversion efficiency of 6.51%. For a comparison, LPD TiO2 film without gradient structure was prepared at a fixed temperature (60 degrees C), which presented a short-circuit current density and photo-to-electric conversion efficiency of 8.78 mA cm (2) and 4.39%, respectively. The electrochemical impedance spectroscopy (EIS) analysis indicated the DSSCs with TiO2 films via two-stage deposition had a lower charge transfer resistance at TiO2/dye/electrolyte interface and a longer electronic lifetime. (C) 2015 Elsevier Ltd. All rights reserved.
Keywords:Anatase TiO2 film;liquid phase deposition;dye-sensitized solar cells;photoanode;electrochemical impedance spectroscopy