Poly(3,4-alkylenedioxypyrrole)s: Highly Stable Electronically Conducting and Electrochromic Polymers

Abstract

A series of poly(3,4-alkylenedioxypyrrole)s are reported as a new class of electronically conducting polymers exhibiting especially low oxidation potentials from ca. −0.6 to −0.4 V vs Fc/Fc+ (equivalent to −0.15 to +0.05 V vs SCE) as desired for ambient stability of the doped and conducting states. These polymers exhibit unique combinations of multicolor electrochromism, switching from a red or orange neutral state to a light blue/gray doped state, passing through a darker intermediate state (brown), as examined by in situ colorimetry. High spectral contrast ratios have been measured throughout the visible region with a maximum Δ%T = 76% at 534 nm for poly[3,4-(2,2-dimethylpropylenedioxy)pyrrole) (PProDOP−(CH3)2). PProDOP−(CH3)2 exhibits outstanding redox switching stability, being able to undergo 40 000 deep double-potential switches between its doped and neutral states (1 s, Δ%Tmax = 76%) while retaining more than 90% of its electroactivity. A high level of stability to overoxidation has also been observed as these materials show limited degradation of their electroactivity at potentials 2 V above their half-wave potential. Triflate-doped free-standing films of PEDOP and PProDOP, having high electrical conductivities of 83 and 95 S/cm, respectively, have been obtained by galvanostatic deposition at low temperature (−7 °C).