Novel blue light-emitting hyperbranched polyfluorenes incorporating carbazole kinked structure

Qi Yuan He, Wen Yong Lai, Zhun Ma, Dao Yong Chen, Wei Huang

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

A novel series of soluble hyperbranched polyfluorenes P1-P6 with various branching degrees and contents of kinked carbazole units were successfully synthesized with good yields and high molecular weight via a facile "A2 + B2 + C3 + D2" approach. The thermal, optical, and electrochemical properties as well as thermal spectral stability of the resulting hypberbranched polymers were investigated. All polymers exhibited good thermal stabilities and bright blue emission in both solutions and solid-states. Hyperbranched polyfluorenes (P3 and P6) exhibited improved spectral stability upon annealing at 200 °C in air, in sharp contrast to the linear poly(9,9-dihexylfluorene) (PDHF) that showed significant additional green emission at ca. 530 nm within minutes. In particular, outstanding spectral stability was observed with carbazole-incorporating hyperbranched polyfluorene P6. Electrochemical characterization indicated that the presence of carbazole also effectively raised the HOMO level with respect to that of polyfluorene homopolymer, suggesting better hole-injection properties. Hence, the incorporation of kinked carbazole unit into hyperbranched polyfluorenes could provide a new methodology for preparing blue light-emitting polymers with improved optoelectronic characteristics.

Original languageEnglish
Pages (from-to)3169-3176
Number of pages8
JournalEuropean Polymer Journal
Volume44
Issue number10
DOIs
StatePublished - Oct 2008
Externally publishedYes

Keywords

  • Blue light-emitting
  • Carbazole
  • Hyperbranched polymer
  • Polyfluorenes

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