The purpose of this work is to decrease the amount of boron trifluoride diethyl etherate (BFEE) usually used during the electrochemical polymerization and enhance the stability of as-formed polymer films. The mixed electrolyte of tetrahydrofuran (THF) and BFEE was used because THF can form a new complex with BF3 which is more stable than BFEE and it also can be the solvent for many kinds of aromatic compound which can be electropolymerized.To increase the ionic conductivity of the mixed electrolyte

Bu4NBF4 was introduced.The ionic conductivity of THF containing 18% BFEE (by volume) and 0.1 mol#8226;L-1 Bu4NBF4 was measured to be 1.25×10-3 S#8226;cm-1.In this medium

highquality polycarbazole (PCZ) films were electrosynthesized successfully by direct oxidation of 0.05 mol#8226;L-1 carbazole.The oxidation potential of carbazole in this medium was measured to be only 0.92 V versus SCE

which was much lower than that determined in acetonitrile containing 0.1 mol#8226;L-1 Bu4NBF4(1.36 V versus SCE).PCZ films obtained from this medium showed good electrochemical behavior

with electrical conductivity of 7.0×10-3 S#8226;cm-1.Asformed PCZ films can be partly dissolved in strong polar organic solvents such as dimethyl sulfoxide.For dedoping

PCZ films were treated with 25% ammonia for 3 days.Then

they were dried at 60℃ for 24 h.The UV-Vis spectra of PCZ showed broader absorption bands mainly at 303 nm

implying wide molar mass distribution.In the fluorescence spectra

the emission peaks of polycarbazole appeared at 415 nm

implying the blue-light-emitting property of PCZ.The FT-IR and 1H-NMR spectral investigations of PCZ indicated that electrochemical polymerization of carbazole mainly occurred at 3

6 positions

in well accordance with the literature reported previously.Thermal analyses indicated that PCZ films prepared from this medium own good thermal stability.The successful electrosyntheses of PCZ films in this mixed electrolyte may extend the applications of this mixed electrolyte of THF

BFEE and Bu4NBF4 in the electrochemical science.