A study on distinctive transition mechanism of sulfuric acid treatment on performance enhancement of poly(3,4-ethylenedioxythiophene): Polystyrene based electrodes depending on multiwall carbon nanotube dose

Abstract For this study, we shall employ the sulfuric acid (H2SO4) treatment to improve the electrode performance of poly(3,4-ethylenedioxythiophene) which is polymerized with poly(4-styrenesulfonate) (PEDOT:PSS) film and composite film consisting of multiwall carbon nanotube (MWNT) and PEDOT:PSS. In both PEDOT:PSS and MWNT/PEDOT:PSS films, the H2SO4 treatment results in the formation of PEDOT-rich crystalline nanofibers while significantly reducing the PSS composition in the electrode. These reactions cause an increase in the electrical conductivity, surface area and catalytic activity of the electrode. However, there still remains obvious distinctions between the PEDOT:PSS and MWNT/PEDOT:PSS films due to the presence of MWNT chains. During this treatment, MWNT chains get closer to the surface and their influence in the surface properties grows, as a large percentage of PEDOT:PSS layers surrounding MWNT chains decrease. Resultantly, unlike PEDOT:PSS film, the MWNT/PEDOT:PSS film has little effect on the alignment of the energy-level including work function. Finally, we shall verify that such distinguished changing trends would also make differences in performance of source/drain electrode in organic thin-film transistors and catalytic counter electrode in dye-sensitized solar cells.