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

Abstract

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/ PEDOT_IL 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/PEDOT_IL and FTO/Gr/PEDOT_IL electrode are demonstrated by scanning electrochemical microscopy (SECM).