Electrochemically Deposited Polypyrrole for Dye-Sensitized Solar Cell Counter Electrodes

Abstract

Polypyrrole films were coated on conductive glass by electrochemical deposition (alternative current or direct current process). They were then used as the dye-sensitized solar cell counter electrodes. Scanning electron microscopy revealed that polypyrrole forms a nanoparticle-like structure on the conductive glass. The amount of deposited polypyrrole (or film thickness) increased with the deposition duration, and the performance of polypyrrole based-dye-sensitized solar cells is dependant upon polymer thickness. The highest efficiency of alternative current and direct current polypyrrole based-dye-sensitized solar cells (DSSCs) is 4.72% and 4.02%, respectively. Electrochemical impedance spectroscopy suggests that the superior performance of alternative current polypyrrole solar cells is due to their lower charge-transfer resistance between counter electrode and electrolyte. The large charge-transfer resistance of direct current solar cells is attributed to the formation of unbounded polypyrrole chains minimizing the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mtext>I</mml:mtext><mml:mn>3</mml:mn></mml:msub><mml:msup><mml:mtext> </mml:mtext><mml:mo>−</mml:mo></mml:msup></mml:mrow></mml:math>reduction rate.