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 degrees C and 85% humidity) is half that of the untreated samples, demonstrating the great enhancement of the stability. (C) 2016 Wiley Periodicals, Inc.