Characterization of poly (vinyl alcohol)/poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) polymer blend: structure, optical absorption, electrical and dielectric properties

Polymer blends of poly (vinyl alcohol) (PVA) and PEDOT:PSS (poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)), were prepared by casting from aqueous solution. They were characterized by x-ray diffraction, scanning electron microscopy, differential scanning calorimetery, thermo gravimetric analysis, Fourier transform infrared, ac spectroscopy and optical UV–visible absorption techniques. The thermal analysis did not illustrate significant variations of PVA when blended with different concentrations of PEDOT:PSS. The bulk conductivity of PVA/PEDOT:PSS blend illustrated a two orders increase, while the activation energy reduced from 0.52 to 0.16 eV with an increasing PEDOT:PSS concentration to 4 wt%. In addition, the frequency dependence of conductivity obeyed the power relation σ ∼ ωs, 0.3 < s < 0.45, which predicts ionic diffusion. The dielectric constant ε-' and dielectric loss ε″ obeyed, at ambient temperature, the Debye dispersion relations in a wide range of frequencies. A new significant optical broad absorption peak appeared in the visible range around 926 nm. Its height increased by increasing the PEDOT:PSS concentration, which was attributed to a direct energy band gap, in the range 1.05–1.2 eV, and plasmon–exciton interaction. (paper)