Electroluminescent fluorene-based alternating polymers bearing triarylamine or carbazole moieties in the main chain: Synthesis and properties

✍ Scribed by Yingping Zou; Yi Zhou; Guanglong Wu; Yongfang Li; Chunyue Pan

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 151 KB
• Volume: 111
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.29156

✦ Synopsis

Abstract

Two soluble conjugated polyfluorenes, poly{9,9‐dioctylfluorene‐2,7‐diyl‐co‐4,4′‐bis[2‐(4‐phenyl)‐2‐cyanovinyl]triphenylamine}(PF‐BCT) and poly{9,9‐dioctylfluorene‐2,7‐diyl‐co‐3,6‐bis[2‐(4‐phenyl)‐2‐cyanovinyl]‐9‐octyl carbazole}(PF‐BCC), have been synthesized from 2,7‐dibromo‐9,9‐dioctylfluorene and 4,4′‐bis[2‐(4‐bromophenyl)‐ 2‐cyanovinyl]triphenylamine or 3,6‐bis[2‐(4‐bromophenyl)‐2‐cyanovinyl]‐9‐octyl carbazole comonomers through a Suzuki polymerization reaction. The copolymers are characterized by gel permeation chromatography, elemental analysis, thermogravimetric analysis. The polymers have good thermal stability with 5 wt % loss temperatures of more than 380°C. Cyclic voltammetry measurements show that the polymers present good electron and hole‐injection abilities. PF‐BCC possesses higher oxidization potential than that of PF‐BCT, which indicates that PF‐BCT has better hole injection ability. The photophysical properties of the polymers are investigated in both solutions and spinning‐coated films. Compared to that of PF‐BCC, the absorption and emission peaks of PF‐BCT bathochromic shift in the solid film or solution states. Single layer light‐emitting devices have been fabricated in the ITO/PEDOT: PSS/polymer/Ca/Al configuration. The electroluminescence (EL) device based on PF‐BCT shows yellow emission with the current efficiency of 0.21 cd/A, while PF‐BCC shows greenish yellow emission with the current efficiency of 0.08 cd/A. In addition, to improve the electroluminescence of PF‐BCC, a PVK layer is introduced, the brightness and efficiency get improved to 700 cd/m^2^ and 0.12 cd/A, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009