Weihua Tang, Tingting Lin, Linder Ke
Dec 1, 2008
Citations
0
Influential Citations
28
Citations
Journal
Journal of Polymer Science Part A
Abstract
2,7-dibromo-N-hexylcarbazole is successfully synthesized in three steps with an overall 37% yield. Novel 2,7-carbazole-based sterically hindered conjugated polymers are further synthesized. In the backbone structure of polymer P1, alkylated bithiophene moiety is β-substituted with dodecyl chains on both thiophene rings, adopting the tail-to-tail configuration. While for polymers P2 and P3, partially planarized thieno[3,2-b]thiophene moiety (P2) and β-pentyl substituted thieno[3,2-b]thiophene (P3) are incorporated. All polymers demonstrate efficient blue-to-green light emission, good thermal stability (Td ≥ 379 °C), and high glass transition temperatures (Tg = 118 °C). The optical and electronic properties of the resulted polymers are tuned by the incorporated alkyl chains. For instance, the incorporation of β-pentyl group in thieno[3,2-b]thiophene moiety endows P3 with blue-shifted photophysical spectra, reduced fluorescence quantum yield and larger band gap in comparison with P2. The steric effect of incorporated alkyl chains is further illustrated by geometry optimization of three model oligomers (analogues to the repetition units of P1–P3) using density functional theory. Sterically hindered polymers P1 and P2 exhibit high charge transport ability and moderate electroluminescent properties in primarily tested single-layer light-emitting diodes (configuration: ITO/PEDOT:PSS/Polymer/Ca/Ag). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7725–7738, 2008