Electrical control of the optical dielectric properties of PEDOT:PSS thin films

Poly (3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) exhibits attractive optical tunability via electrochemical redox doping under applied voltages. Here, the influence of applied voltage on the optical parameters of PEDOT:PSS thin films was systemically investigated. The PEDOT:PSS film was prepared by the spin-coating method. A well-defined reduction degree from 0 to 100% was set in a Na+ electrolyte by using electrochemical analysis. The biaxial anisotropy optical complex refractive index of PEDOT:PSS thin films at different reduction degrees were determined in the entire visible spectrum by using the variable angle ellipsometry spectrometer combined with the Drude-Lorentz model. The results show that both the refractive index and the extinction coefficient increase with the increase of the reduction degree. This implies potential applications for PEDOT:PSS films on electrically controlling devices.