External quantum efficiency exceeding 24% with CIEy value of 0.08 using a novel carbene-based iridium complex in deep-blue phosphorescent organic light-emitting diodes

Ho-Yeol Park, Athithan Maheshwaran, Chang-Ki Moon, Hyuna Lee, Saripally Sudhaker Reddy, Vijaya Gopalan Sree, Jiyoung Yoon, Jeong Won Kim, Jang Hyuk Kwon, Jang-Joo Kim, Sung-Ho Jin

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24 Citations (Scopus)


Deep-blue triplet emitters remain far inferior to standard red and green triplet emitters in terms of exhibiting high-color-purity Commission International de l'Éclairage (CIE) y values of ≤0.1, external quantum efficiencies (EQEs), and high electroluminescent brightnesses in phosphorescent organic light-emitting diodes. In fact, no deep-blue triplet emitter with color purity and high device performance has previously been reported. In this study, a deep-blue triplet emitter, mer-tris(N-phenyl, N-benzyl-pyridoimidazol-2-yl)iridium(III) (mer-Ir1) is developed, which meets the requirements of the National Television System Committee (NTSC) CIE(x, y) coordinates of (0.149, 0.085) with an extremely high EQE of 24.8% and maximum brightness (Lmax) of 6453 cd m−2, by a device with a 40 vol% doping ratio. Moreover, another device demonstrates an EQEmax of 21.3%, an Lmax of 5247 cd m−2, and CIE(x, y) coordinates of (0.151, 0.086) at a 30 vol% doping ratio. This is the first report of a high-performance, deep-blue phosphor, carbene-based Ir(III) complex device with outstanding CIE(x, y) color coordinates and a high EQE. The results of this study indicate that the novel dopant mer-Ir1 is a promising candidate for reducing power consumption in display applications.

Original languageEnglish
Article number2002120
Number of pages8
JournalAdvanced Materials
Issue number29
Publication statusPublished - 23 Jul 2020
Externally publishedYes


  • carrier balance
  • concentration quenching
  • deep-blue phosphorescence
  • N-heterocyclic carbene ligands
  • organic light-emitting diodes

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