Influence of Solvent of in situ Electro-Polymerization on Catalytic Performance of PEDOT Counter Electrode

In this work, we discuss the catalytic performance of poly(3,4-ethylenedioxythiophene) (PEDOT) counter electrode prepared via electro-polymerization (EP) method in Na2SO4 aqueous solution and [BMIM]BF4 ionic liquid for dye-sensitized solar cells (DSSCs), respectively. The electrochemical and photoelectric conversion tests result show that [BMIM]BF4 is more beneficial to dissolve EDOT and thereby promote the growth of 3D PEDOT which can increase the catalytic activity. Furthermore, the introduced graphite (Gr) buffer layer can improve the roughness of PEDOT and F-doped tin oxide substrate (FTO), However, in the [BMIM]BF4 ionic liquid, the overgrowth PEDOT on Gr will reduced the properties of the counter electrode (CE) compare to CE without Gr buffer layer. Further, by using the Gr/ PEDOTIL counter electrode, a 4.89% of photoelectric conversion efficiency(PCE, η) was obtained which was up to 82.3% of DSSC–Pt (η = 5.94%) at the same condition. Meanwhile, the electro-catalytic activity of FTO/PEDOTIL and FTO/Gr/PEDOTIL electrode are demonstrated by scanning electrochemical microscopy (SECM).