Electro-conductive properties of poly(3,4-ethylenedioxythiophene)/poly(ionic liquid) films with respect to its structure and morphology

Poly(3,4-ethylenedioxythiophene) (PEDOT)/poly(1-vinyl-3-ethylimidazolium+ (trifluoromethane sulfonyl)imide−) (PIL) complexes were prepared at various PEDOT/PIL molar ratios and dispersed in propylene carbonate at a concentration of 1 wt%. After casting, the maximum conductivity was measured to be 1.2 × 10−1 S/cm, which could be explained by the 3D variable range hopping model. The optimum surface roughness of the PEDOT/PIL film was measured, showing Sa and Sq values of 5.92 and 11.0 nm, respectively. The conductivity of the polymerized PEDOT without a template process had low conductivity due to its poor surface roughness and large particle size. Therefore, the conductivity of PEDOT/PILs is determined by the particle size, crystallinity and surface morphology. These results were supported by surface mapping microscopy, X-ray photon spectroscopy, and X-ray diffraction.