Low-potential electrochemical polymerization of carbazole and its alkyl derivatives Zhenhong Wei a , Jingkun Xu a, * , Guangming Nie b , Yukou Du c , Shouzhi Pu a a Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, Fenglin Street, Changbei District, Nanchang, 330013 Jiangxi Province, PR China b College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao, 266042 Shandong Province, PR China c Department of Chemistry and Chemical Engineering, Suzhou University, Suzhou, 215006 Jiangsu Province, PR China Received 2 November 2005; received in revised form 15 January 2006; accepted 20 January 2006 Available online 20 March 2006 Abstract High quality polymer films can be easily electrodeposited by low-potential anodic oxidation of carbazole and its alkyl derivatives N- octylcarbazole, N-(6-bromohexyl)carbazole, 1,6-bis(carbazolyl)hexane in boron trifluoride diethyl etherate (BFEE) or mixed electrolytes BFEE + CHCl 3 . As-formed polymer films showed good redox behavior in monomer free BFEE and were characterized by UV–Vis, infrared, fluorescence spectroscopy and thermal analysis. Fluorescence spectral studies both in solution and in solid state revealed that as-formed polymer films were good blue light emitters with strong emissions at about 420 and 440 nm, respectively. Ó 2006 Elsevier B.V. All rights reserved. Keywords: Electrochemical polymerization; Conducting polymers; Polycarbazole; Boron trifluoride diethyl etherate; Fluorescence properties 1. Introduction During the past two decades, conjugated polymers with different chemical structures emitting different colors in the whole visible range have been widely investigated, and devices based on these materials have been fabricated. These organic electroactive and photoactive materials are usually based on thiophene, pyrrole, phenylene, fluorene, or carbazole moieties. Among them, increasing interest has been paid to polycarbazoles (PCzs) because they are one of the most promising candidates for hole-transporting and photoluminescence efficiencies units [1–5]. Moreover, PCzs have the possibility of substitution at N position. This facile process provides the opportunity to improve both the solubility and functionality of the resulting polymer. On the other hand, flexible side chains can cause steric hin- drance and thereby provide a means to control the effective conjugation length and thus tuning the color of the emit- ting light in devices. In the case of carbazole-based conjugated polymers, all previous studies were devoted to 3, 6-linked N-substituted carbazole units [6–9]. As reported for many other conju- gated polymers, the synthesis of well-defined carbazole polymer has been sustained by the clever utilization of a variety of synthetic tools, such as Kumada, Stille, Yamam- oto, Suzuki couplings, etc. [10–14]. Although these conju- gated polymers showed interesting electrochemical, electrochromic, electrical, light-emitting, and photorefrac- tive properties, the yield of products obtained from chem- ical approaches was very low and the synthesis cost was very high. On the other hand, electrochemical polymeriza- tion has been proved to be one of the most useful approaches for conducting polymers synthesis with several advantages. It can form conducting thin film on the work- ing electrode by one step. The amount of polymer depos- ited on the electrode can be controlled by the integrated charge passed through the cell. However, previous studies indicated that the quality of PCz films electrodeposited in 0022-0728/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jelechem.2006.01.023 * Corresponding author. Tel.: +86 791 3805193; fax: +86 791 3826894. E-mail addresses: xujingkun@tsinghua.org.cn, xujingkun@mail.ipc. ac.cn (J. Xu). www.elsevier.com/locate/jelechem Journal of Electroanalytical Chemistry 589 (2006) 112–119 Journal of Electroanalytical Chemistry