Photoinduced Step-Growth Polymerization of N-Ethylcarbazole

A novel method for photochemical step-growth synthesis of poly(N-ethylcarbazole) (PEC) via consecutive diphenyl iodonium hexafluorophospate (Ph₂I⁺PF₆ ^-) mediated electron transfer and coupling reactions is reported. The photoinduced electron transfer reaction of the excited N-ethylcarbazole (EC) in the presence of Ph₂I⁺PF₆ ^- as the oxidizing salt proceeded efficiently giving EC radical cations (EC^+•). Subsequently, the protons released concomitantly with coupling of two EC radical cations. The successive reactions involving excitation, electron transfer, proton release, and coupling lead to the formation of PEC. The electrochemical properties and surface morphology of the thin films of the formed polymers before and after dedoping were investigated by cyclic voltammetry, differential pulse voltammetry, and atomic force microscopy techniques, respectively.