Fluorinated carbazole derivatives as wide-energy-gap host material for blue phosphorescent organic light-emitting diodes

Yukitami Mizuno, Isao Takasu, Shuichi Uchikoga, Shintaro Enomoto, Tomoaki Sawabe, Akio Amano, Atsushi Wada, Tomoko Sugizaki, Jiro Yoshida, Tomio Ono, Chihaya Adachi

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)

Abstract

2,7-Difluo-carbazole and 2,4,5,7-tetrafluoro-carbazole were synthesized as new building blocks of wide-energy-gap host material for phosphorescent organic light-emitting diodes (PHOLEDs). These fluorinated positions in the carbazole ring were determined on the basis of density functional theory calculation results. Spectroscopic analyses supported the hypothesis that poly(N-vinyl-2,7-difluoro-carbazole) (2,7-F-PVK) with the fluorinated pendant group possessed a wide energy gap, leading to the exciton energy confinement on the blue phosphorescent dopant as well as nonsubstituted poly(N-vinyl-carbazole) (PVK). 2,7-F-PVK was used in solution-processed blue PHOLED to achieve 27 cd/A at 760 cd/m 2, which is 1.8 times higher than that of nonsubstituted PVK. We assumed that the replacement of nonsubstituted PVK with 2,7-F-PVK improved the charge balance in the emission layer, while keeping the exciton confinement effect. The fluorination of the carbazole ring is a useful molecular design strategy for wide-energy-gap host material.

Original languageEnglish
Pages (from-to)20681-20687
Number of pages7
JournalJournal of Physical Chemistry C
Volume116
Issue number39
DOIs
Publication statusPublished - Oct 4 2012

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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