Electrochemical polymerization of 9-phenylcarbazole in mixed electrolytes of boron trifluoride diethyl etherate and sulfuric acid

Poly(9-phenylcarbazole) (P9PC) films were synthesized electrochemically by direct anodic oxidation of 9-phenylcarbazole in boron trifluoride diethyletherate (BFEE) containing additional 2% sulfuric acid (by volume). The oxidation potential onset of 9-phenylcarbazole in this medium was measured to be 0.9 V vs. SCE, which was much lower than that in acetonitrile containing 0.1 mol L-1 Bu4NBF4 (1.1 V vs. SCE). P9PC films obtained from this medium showed good electrochemical behavior and good thermal stability with an electrical conductivity of 0.09 S cm-1. The structure and morphology of the polymer were investigated by UV–visible spectroscopy, infrared spectroscopy, and scanning electron microscopy (SEM), respectively. The results of quantum chemistry calculations of 9-phenylcarbazole monomer indicated that the polymerization mainly occurred at C3 and C6 positions. Fluorescent spectral studies indicated that P9PC was a blue-light emitter.