Highly Efficient Blue OLEDs Based on Metal-Assisted Delayed Fluorescence Pd(II) Complexes

Zhi Qiang Zhu, Choong Do Park, Kody Klimes, Jian Li

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


A series of metal-assisted delayed fluorescence (MADF) palladium(II) complexes, PdN1N, PdN1N-dm, and PdN6N, are studied. Their 77 K photoluminescence emission spectra show a narrow primary emission peak at 464, 466, and 470 nm, respectively, with small vibronic peaks characteristic of many phosphorescent emitters. At room temperature (300 K), the dominant emission peaks for PdN1N, PdN1N-dm, and PdN6N are slightly redshifted to 472, 470, and 476 nm, respectively. In the meantime, a broad sideband is also shown between 410 and 450 nm due to the MADF process. A blue device employing PdN1N-dm demonstrates an electroluminescence emission peak at 476 nm and the maximum external quantum efficiency (EQE) of 25.1%. The high maximum EQE of the blue organic light-emitting diode (OLED) device indicates that both the phosphorescence and the delayed fluorescence are very efficient. In addition, a stable OLED device of PdN1N-dm gives a maximum EQE of 9.8% and the estimated operational lifetime LT 70 of 350 h at the practical luminance of 100 cd m −2 .

Original languageEnglish (US)
Article number1801518
JournalAdvanced Optical Materials
Issue number6
StatePublished - Mar 19 2019


  • Pd(II) complex
  • blue organic light-emitting diodes
  • external quantum efficiency
  • metal-assisted delayed fluorescence
  • operational stability

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics


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