Selectively controlled orientational order in linear-shaped thermally activated delayed fluorescent dopants

Takeshi Komino, Hiroyuki Tanaka, Chihaya Adachi

Research output: Contribution to journalArticle

69 Citations (Scopus)

Abstract

The orientational order of a linear-shaped thermally activated delayed fluorescent dopant 10-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-10H- phenoxazine (PXZ-TRZ) was selectively controlled in a randomly oriented host matrix composed of 3,3-di(9H-carbazol-9-yl)biphenyl (mCBP) by varying the temperature during deposition of the thin films. Although the molecular orientation of mCBP was random at deposition temperatures ranging from 200 to 300 K (orientational disorder), PXZ-TRZ molecules oriented horizontal to the substrate in this temperature range (high orientational order). This indicates that the orientational order was dominated by the kinetic behavior of PXZ-TRZ at the film surface rather than by randomization caused by aggregation of PXZ-TRZ and mCBP molecules. Using an orientation-controlled 6 wt % PXZ-TRZ:mCBP film as an emitting layer, we fabricated organic light-emitting diodes (OLEDs). The horizontal orientation of the dopants enhanced the external electroluminescence quantum efficiency of the OLED by 24% compared with that of the corresponding OLED with slightly vertical orientation. An optical simulation found that the enhancement originates mainly from the improvement of the light out-coupling efficiency.

Original languageEnglish
Pages (from-to)3665-3671
Number of pages7
JournalChemistry of Materials
Volume26
Issue number12
DOIs
Publication statusPublished - Jun 24 2014

All Science Journal Classification (ASJC) codes

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

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