Journal
CHEMISTRY-A EUROPEAN JOURNAL
Volume 21, Issue 22, Pages 8250-8256Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/chem.201500517
Keywords
doping; electrophosphorescence; host materials; light-emitting diodes; luminescence
Categories
Funding
- National Basic Research Program of China (973 Program) [2013CB834805, 2015CB655002]
- National Science Fund for Distinguished Young Scholars of China [51125013]
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An adamantane-based host material, namely, 4-{3-[4-(9H-carbazol-9-yl)phenyl]adamantan-1-yl}benzonitrile (CzCN-Ad), was prepared by linking an electron-donating carbazole unit and an electron-accepting benzonitrile moiety through an adamantane bridge. In this approach, two functional groups were attached to tetrahedral points of adamantane to construct an sp(3) topological configuration. This design strategy endows the host material with a high triplet energy of 3.03eV due to the disruption of intramolecular charge transfer. Although CzCN-Ad has a low molecular weight, the rigid nonconjugated adamantane bridge results in a glass transition temperature of 89 degrees C. These features make CzCN-Ad suitable for fabricating blue phosphorescent organic light-emitting diodes (PhOLEDs). The devices based on sky-blue phosphor bis[(4,6-difluorophenyl)pyridinato-N,C-2](picolinato)iridium(III) (FIrpic) achieved a high maximum external quantum efficiency (EQE) of 24.1%, which is among the best results for blue PhOLEDs ever reported. Furthermore, blue PhOLEDs with bis(2,4-difluorophenylpyridinato)-tetrakis(1-pyrazolyl)borate iridium(III) (FIr6) as dopant exhibited a maximum EQE of 14.2% and a maximum luminance of 34262cdm(-2). To the best of our knowledge, this is the highest luminance ever reported for FIr6-based PhOLEDs.
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