Optical and electrical properties of PEDOT:PSS doped with polar solvents

Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) has become one of the most widely used conductive polymers due to its stable conductivity, good flexibility, high light transmittance, and other advantages. In this study, PEDOT:PSS films with single doping of dimethyl sulfoxide (DMSO) or ethylene glycol (EG) and binary doping were prepared by spray coating. The electrical and optical properties of the films under different doping systems were compared. The experimental results revealed that the optical and electrical properties of binary doping are better. To explain this enhancement mechanism, multiscale molecular modeling, including density functional theory calculations and molecular dynamics simulations, was carried out. We demonstrated that DMSO cannot form hydrogen bonds with deprotonated PSS-, while EG can. Moreover, the synergistic effect of DMSO and EG can more effectively remove the insulating PSS. In addition, we found that the alterations in the morphology and structure of PEDOT induced by polar solvent doping represent the pivotal factor contributing to the improvement in the light transmittance of PEDOT:PSS films.