Effect of pH on Structure and Conductivity of PEDOT/PSS

Abstract

Poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT/PSS) was synthesized by oxidative polymerization and pH dependence of structure and electrical conductivity of the cast films were investigated by means of UV-vis-NIR, XRD, AFM analyses, and four-point technique. It was found that the neutralization of PEDOT/PSS with NaOH decreased the absorption of bipolarons representing the PEDOT in the highly doped state and disrupted the π-π stacking of the PEDOT crystalline structure, which lowered the electrical conductivity by six orders of magnitude with increasing the pH from 1.7 to 13.

The damaging effects of the acidity in PEDOT:PSS on semiconductor device performance and solutions based on non-acidic alternatives

“…However, Okuzaki et al showed that making PEDOT:PSS pH neutral can cause distinct changes in the properties with reduced conductivity, increased absorption in the NIR region and reduced order in the film. 35 Additionally, de Kok and co-workers analysed PEDOT:PSS when treated with sodium hydroxide. Typically PEDOT:PSS shows broad absorption in the NIR region which is attributed to bipolarons ( Fig.…”

Mechanically enhanced electrically conductive films from polymerization of 3,4‐ethylenedioxythiophene with wood microfibers

“…The 8% weight loss resulted from soaking in NaOH does not explain the considerable increase in sheet resistivity. The detrimental effect of high pH on conductivity was attributed by Mochizuki et al . to the change in PEDOT:PSS from a higher doped state (bipolarons) to a less doped state (polarons).…”

Influence of anionic and cationic polyelectrolytes on the conductivity and morphology of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) films

“…Mixing the secondary structure with water induces formation of colloidal particles (tertiary structure) consisting up to 90-95% of water with hydrophobic PEDOT groups being pushed into the center of the particle surrounded by water and anionic PSS. These colloidal particles are the building blocks of conductive PEDOT:PSS films and coatings (quaternary structure) [37].…”