Multi‐responsive Electropolymer Surface Coatings Based on Azo Molecular Switches and Carbazoles: Light, pH, and Electrochemical Control of Z→E Isomerization in Thin Films

Abstract

Light‐responsive surfaces are attracting increasing interest, not least because their physicochemical properties can be selectively and temporally controlled by a non‐invasive stimulus. Most existing immobilization strategies involve the chemical attachment of light‐responsive moieties to the surface, although this approach often suffers from a low surface concentration of active species or a high inhomogeneity of applied coatings. Herein we present electropolymerization of carbazoles as a facile and rapid approach for preparing light‐responsive azo‐based surface coatings. The electrochemical oxidative polymerization of bis‐carbazole containing azo‑monomers yields stable films in which the photochemical properties and specific pH sensitivity of azo molecular switches are retained. Moreover, the molecular design enables electrocatalytic control over Z → E azo double bond isomerization facilitated by the conductive polycarbazole backbone. Ultimately, the high degree of control over macromolecular properties yields conductive surface coatings responsive to a range of stimuli, showing great promise as a strategy for versatile application in organic electronics.