Effect of electropolymerization duration on the structure and performance of polypyrrole/graphene nanoplatelet counter electrode for dye-sensitized solar cells

Despite their potential for use as a low-cost energy-conversion device, dye-sensitized solar cells (DSSCs) have not been widely utilized because they apply platinum as a counter electrode, necessitating the use of an alternative, inexpensive material as a counter electrode. In this study, a polypyrrole-covered graphene nanoplatelet (PPy/GN) film was prepared by the electrochemical method, and a DSSC was synthesized using the PPy/GN film as a counter electrode. Analysis by Raman spectroscopy confirmed that the electropolymerized PPy contained oxidized PPy, and the structure of PPy could be changed by changing the duration of polymerization. The presence of oxidized PPy decreased the performance of the PPy/GN electrodes, and the charge transfer resistance between the electrolyte ion and PPy/GN decreased by decreasing the content of oxidized PPy. The conversion efficiency ( η ) of the DSSCs increased with the use of PPy/GN electrodes, and a maximum η of 4.3 % was comparable to that of the cells with sputtered Pt electrodes.