Synthesis and characterization of indeno[1,2-6] fluorene-based white light-emitting copolymer

Eunjae Jeong, Sun Hee Kim, In Hwan Jung, Yangjun Xia, Kwanghee Lee, Hongsuk Suh, Hong Ku Shim, Han Young Woo

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33 Citations (Scopus)

Abstract

An indenofluorene-based copolymer containing blue-, green-, and red light-emitting moieties was synthesized by Suzuki polymerization and examined for application in white organic light-emitting diodes (WOLEDs). Tetraoctylindenofluor-ene (IF), 2,1,3-benzothiadiazole (BT), and 4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (DBT) derivatives were used as the blue-, green-, and red-light emitting structures, respectively. The number-average molecular weight of the polymer was determined to be 25,900 g/mol with a polydispersity index of 2.02. The polymer was thermally stable (T d = ∼398 °C) and quite soluble in common organic solvents, forming an optical-quality film by spin casting. The EL characteristics were fine-tuned from the single copolymer through incomplete fluorescence energy transfer by adjusting" the composition of the red/green/blue units in the copolymer. The EL device using the indenofluorene-based copolymer containing 0.01 mol % BT and 0.02 mol % DBT units (PIF-BT01-DBT02) showed a maximum brightness of 4088 cd/m2 at 8 V and a maximum current efficiency of 0.36 cd/A with Commission Internationale de L'Eclair-age (CIE) coordinates of (0.34, 0.32). The EL emission of PIF-BT01-DBT02 was stable with respect to changes in voltage. The color emitted was dependent on the thickness of the active polymer layer; layer (∼60 nm) too thin was unsuitable for realizing WOLED via energy transfer.

Original languageEnglish
Pages (from-to)3467-3479
Number of pages13
JournalJournal of Polymer Science, Part A: Polymer Chemistry
Volume47
Issue number14
DOIs
Publication statusPublished - 2009 Jul 15
Externally publishedYes

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Keywords

  • Conjugated polymers
  • Copolymerization
  • Light-emitting diodes (LED)

ASJC Scopus subject areas

  • Polymers and Plastics
  • Organic Chemistry
  • Materials Chemistry

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