Red emitting phenothiazine dendrimers encapsulated 2-{2-[2-(4- dimethylaminophenyl)vinyl]-6-methylpyran-4-ylidene}malononitrile derivatives

Go Woon Kim, Min Ju Cho, Young Jun Yu, Zee Hwan Kim, Jung Il Jin, Dong Young Kim, Dong Hoon Choi

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

New red light emitting dendrimers were synthesized by reacting 2-[2-(2-{4-[bis(6-hydroxyhexyl)amino]-phenyl}vinyl)-6-methylpyran-4-ylidene] malononitrile (15) or 2-[2,6-bis(2-{4-[bis(6-hydroxyhexyl)amino]-phenyl}vinyl) pyran-4-ylidene]malononitrile (16) with 3,5-bis{3,5-bis[2-(10-hexyl-10H- phenothiazin-3-yl)vinyl]benzyloxy}benzoic acid (9) by DCC catalyzed esterification. Two kinds of red emitting core dyes capable of electronic excitation via Förster energy transfer were encapsulated by phenothiazine (PTZ) dendrons. Photoluminescence (PL) studies of the dendrimers demonstrated that, at the high density of a PTZ dendron, a significantly high-energy transfer to the core is achieved as a result of the large overlap between the absorption spectrum of a core emitting dye and the PL spectrum of the PTZ dendron. The electroluminescence (EL) spectra of multilayered devices showed red emissions, similar to those observed in the PL spectra of dendrimer thin films. The multilayered devices showed a luminance of 490 cd/m2 at 254 mA/cm2 (11.4 V) for 17 and 210 cd/m2 at 321 mA/cm 2 (11.7 V) for 18. The EL quantum efficiency of 18 (ηext = 0.56%) increased with an increase in the density of a light-harvesting PTZ dendron. The larger dendrimer, 18 bearing a more polar emitting core exhibited a considerably pure red emission with CIE 1931 (Commission International de L'Eclairage) chromaticity coordinates of x = 0.64, y = 0.34.

Original languageEnglish
Pages (from-to)42-50
Number of pages9
JournalChemistry of Materials
Volume19
Issue number1
DOIs
Publication statusPublished - 2007 Jan 9

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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