Theoretical and Electrochemical Analysis of Poly(3,4-alkylenedioxythiophenes): Electron-Donating Effects and Onset of p-Doped Conductivity

Conducting polymers have widespread industrial applications owing to a unique combination of mechanical, optical, and electronic properties. Specifically, the family of poly(alkylenedioxythiophene) derivatives has received much attention due to its inherently high conductivity, environmental stability, and tunability. However, although the electron-donating characteristics of the alkoxy moieties are well-known, the source of the differences among these substitutions has been limited to speculative arguments based on bulk properties. To address these issues, a combined electrochemical and density functional theory (DFT) study was undertaken that reveals the significant electronic and geometric characteristics responsible for the comparative properties of these materials. It wits found that the geometry of the alkylenedioxy backbone substitution modulates the pi-donating character of the oxygen and that this directly influences the onset of p-doped conductivity. These studies also indicate that this framework equally applies to several other heterocyclic polymer systems. An improved theory for these materials is expected to provide the insight and knowledge base for new conducting polymers with enhanced stability and optoelectronic properties.