Inhomogeneity effects in vapor phase polymerized PEDOT: A tool to influence conductivity

Low-MW urethanes were investigated to control domain formation as well as inhibiting cleavage reactions during vapor phase polymerization of PEDOT. A diurethanediol (DUDO) was identified as a highly efficient mediator for the process, resulting in PEDOT films exceeding conductivities of 1000 S·cm^-1. All the urethanes investigated had the desired inhibiting effect on the polymerization, but all apart from DUDO also introduced unwanted domain formation on the micrometer scale. The addition of PEG generally improved conductivity by suppressing the domain formation and, with an optimized combination of DUDO and PEG, conductivities over 1200 S·cm^-1 were achieved. The use of low-MW urethanes and PEG can provide control over the domain formation during vapor-phase polymerization of PEDOT. With optimized ratios of PEG and a diurethanediol conductivities exceeding 1200 S·cm^-1 are obtained. The urethanes investigated all have the ability to suppress the unwanted cleaving reaction of EDOT during the polymerization.