Sequential Doping Reveals the Importance of Amorphous Chain Rigidity in Charge Transport of Semi-Crystalline Polymers

Sequential doping is a promising new doping technique for semicrystalline polymers that has been shown to produce doped films with higher conductivity and more uniform morphology than conventional doping processes, and where the dopant placement in the film can be controlled. As a relatively new technique, however, much work is needed to understand the resulting polymer–dopant interactions upon sequential doping. A combination of infrared spectroscopy and theoretical simulations shows that the dopants selectively placed in the amorphous regions in the film via sequential doping result in highly localized polarons. We find that the presence of dopants within the amorphous regions of the film leads to an increase in conjugation length of the amorphous chains upon doping, increasing film connectivity and hence improving the overall conductivity of the film compared with the conventional doping processes.