Influence of imidazole-based acidity control of PEDOT:PSS on its electrical properties and environmental stability

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been studied for a wide range of applications due to its potential as a transparent electrode. Herein, the use of imidazole and its derivatives as a neutralizing additive for PEDOT:PSS dispersion and in-depth studies of their effects in terms of electrical properties and stability is reported. Although the neutralization in general reduces the electrical conductivity of PEDOT:PSS, the conductivity after imidazole treatment (685.2 S cm⁻¹) is higher than that after treatment of other derivatives. Spectroscopic and thermoelectric studies show that the de-doping effect resulted in the conductivity reduction. As a trade-off of the conductivity reduction, greatly enhanced long-term stability and noncorrosive characteristics are obtained after neutralization. The change in sheet resistance of imidazole-treated PEDOT:PSS after 500 h under harsh conditions (85 °C and 85% humidity) is half that of the untreated samples, demonstrating the great enhancement of the stability.