Novel Platinum-Free Counter-Electrode with PEDOT: PSS-Treated Graphite/Activated Carbon for Efficient Dye-Sensitized Solar Cells

Abstract

Developing an efficient material as a counter electrode (CE) with excellent catalytic activity, intrinsic stability, and low cost is essential for the commercial application of dye-sensitized solar cells (DSSCs). Photovoltaic properties DSSCs fabricated with low-cost and platinum-free CEs based on different mixtures of carbon allotropes graphite (GR), activated carbon (AC) and PEDOT: PSS films. The DSSCs assembled with PEDOT: PSS/GR/AC showed an impressive photovoltaic conversion efficiency of 4.60%, compared to 4.06% for DSSCs with GR/AC CE or 1.66% for PEDOT: PSS alone or 6.56 % for Pt under the illumination 100 mW cm− 2 (AM 1.5 G) due to the superior electrocatalytic activity and the conductivity of AC and PEDOT: PSS. The fabricated carbon counter electrodes were extensively characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, cyclic voltammetry (CV), Tafel measurements and electrochemical impedance spectroscopy (EIS). The CV, EIS and Tafel measurements indicated that the PEDOT: PSS/Graphite/AC composite film has low charge-transfer resistance on the electrolyte/CE interface and high catalytic activity for the reduction of triiodide to iodide than the GR/AC CEs. It is potentially feasible that such a carbon configuration can be used as a counter electrode, replacing the more expensive Pt in DSSCs.