Blue emitting OLED with star-shaped multi-functional oligomer

Meng Lian Gong*, Neng Jun Xiang, K. L. Tong, Tik Ho Lee, Shu Kong SO, Louis M L LEUNG

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review


A fluorescent star-shaped oligomer with a nitrogen atom as a core and both a hole transporting arylamine and an electron transporting 1,3,4-oxadiazole moiety, tri(4-(5-phenyl-1, 3, 4-oxadiazol-2-yl)phenyl)amine (TPOPA), has been designed and synthesized using a 5-step reaction procedure. The synthesized compound was characterized by elemental analysis, 1H-NMR and mass spectroscopy. Thermogravimetric (TG) and differential scanning calorimetry (DSC) analysis show that TPOPA exhibits high thermal stability (7d, 373°C) and high glass-transition temperature (Tg 116°C). Photoluminescence measurements indicate that the star-shaped oligomer shows intense blue emission peaked at 445 nm with a high quantum yield of 0.68 under near UV light excitation. The HOMO value of TPOPA is -5.64 eV and the LUMO is -2.58 eV based on the electro-chemical determinations. Reversible anodic oxidation results suggest that the electron-transporting is predominant for TPOPA. Two single layered devices were fabricated by vacuum evaporation with configurations of ITO / CuPC (15 nm) / TPOPA (95 nm) / Ca(30 nm) / Al(100 nm) (device 1) and ITO / CuPC(15 nm) / TPOPA (175 nm) / Ca(30 nm) / Al(100 nm) (device 2), where TPOPA was used both as emitter and carrier - transporting material, CuPC as a hole-injection and electron block material. The devices show blue wide-band emission peaked at 438 nm with a maximum luminance of 650 cd/m2 and 512 cd/m2 under an operating voltage of 12 V, respectively.

Original languageEnglish
Article number63331H
JournalProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - 2006
EventOrganic Ligh Emitting Materials and Devices X - San Diego, CA, United States
Duration: 13 Aug 200616 Aug 2006

Scopus Subject Areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

User-Defined Keywords

  • Ambipolar oliogomer
  • Arylamine
  • OLED
  • Oxadiazole


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