Translated structural morphology of conductive polymer nanofilms synthesized by vapor phase polymerization

Vapor phase polymerization (VPP) is at the forefront for synthesizing highly conductive poly(3,4-ethylenedioxythiophene) (PEDOT). However, little attention has been directed towards the factors affecting chain growth in solid-state polymerization. In this study, we revealed the VPP growth mechanism of a PEDOT film and thus provided a link to the structure-property relationship. Our results show that the monomers are activated on the oxidant layer and the chain growth is guided by the substrate morphology via diffusion into the oxidant layer, producing a thin PEDOT-stuffed layer. Further film growth proceeds through diffusion of the monomer into the oxidant layer following the structural texture of the oxidant film. This reaction-diffusion process generates a propagating PEDOT-stuffed/oxidant interface (with a constant velocity), thus leading to the film growth. As a result, the film grows linearly with EDOT evaporation time and the structural texture of the oxidant film was translated to the PEDOT film, thus determining the critical properties, such as the morphology, conductivity, and transparency of the film.