Impacts of sputter-deposited platinum thickness on the performance of dye-sensitized solar cells

The thickness of platinum thin film and surface roughness of the platinized counter electrode can be determined by sputtering time. A larger surface roughness is beneficial to the charge transfer efficiency and electrocatalytic activity of platinized counter electrode. When the sputtering time of 40 s is used, the dye-sensitized solar cell exhibits the largest short-circuit photocurrent density and the highest energy conversion efficiency of 6.81%. When the sputtering duration is over 80 s, both short-circuit photocurrent density and energy conversion efficiency are largely reduced. A thicker platinum film is not favorable for improving the performance of dye-sensitized solar cell. The optimum platinum thickness for sputter-deposited counter electrode approximates to 30 Å. The increase of peak height and peak area in cyclic voltammetric plot demonstrates larger active surface area and enhanced electrocatalytic activity of the platinized counter electrode. The dependence of short-circuit photocurrent density on platinum thickness has been further explored by electrochemical impedance spectroscopy. Corresponding charge transfer resistances at various platinum/electrolyte interfaces are obtained by simulation on the impedance spectra. This study has evidenced that the thickness of platinum greatly influences the electrocatalytic ability of platinized counter electrode and is certainly a significant factor for the performance of dye-sensitized solar cell.