Direct electrodeposition of thin‐layer (phenylene–carbazolylene) copolymers

Thin (phenylene–carbazolylene) copolymer films of controlled composition can be directly deposited onto solid cathodes such as indium tin oxide (ITO) glass or glassy carbon through a dehalogenative polycondensation of 4,4′‐dibromobiphenyl and 3,6‐dibromo‐ N ‐alkylcarbazole mixtures in the presence of an electrogenerated zero‐valent nickel catalyst. The electrochemical and optical properties of the resulting thin films have been studied. The electrochemical behavior reveals two distinct electronic states that depend on the copolymer composition and structure. The first electronic state is characterized by either only one redox process, attributed to the presence of phenylene‐disubstituted carbazolic units in the case of copolymers with the highest proportion of phenylene, or two successive redox processes, attributed to the occurrence of a radical cation and dication of carbazolic diades, in the case of copolymers with the lowest proportion of phenylene. The second electronic state shows in all cases a single redox system occurring at a higher potential than the first state and due to phenylene moieties in the copolymer. All the electrodeposited copolymer films were found to be reducible in the same manner as pure poly( p ‐phenylene).