Graphene-modified polyaniline as the catalyst material for the counter electrode of a dye-sensitized solar cell

A nanocomposite thin film, consisting of graphene (GN) and polyaniline (PANI) (designated as GN/PANI) is coated as a catalytic layer on an FTO glass by electro-polymerization from a solution containing aniline (ANI) monomers and GNs; the thus coated electrode is used as a counter electrode (CE) for a dye-sensitized solar cell (DSSC). Modification of the surface of GNs by the ANI monomers is confirmed by thermo-gravimetric analysis (TGA). Fourier transform spectroscopy (FTIR) and UV/Vis absorption spectra are used to demonstrate the non-covalent interactions between ANI and GN in the GN/ANI particles. The effect of the refluxing process on the dispersibility of GN/ANI particles in an aqueous solution is studied. The high electro-catalytic ability of GN/PANI-CE is established through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The short-circuit current density (J _SC) and power-conversion efficiency (η) of the DSSC with the GN/PANI-CE are measured to be 16.28 mA cm ^-2 and 7.17%, respectively, while the corresponding values are 15.01 mA cm ^-2 and 7.24% for a DSSC with a CE having Pt as the catalytic material (Pt-CE). The composite film of GN/PANI is thus established to be a potential catalyst for replacing the expensive, conventional Pt in a DSSC.