Strategic molecular engineering of blue phosphorescent Pt(II)compounds for the development of high-efficiency single-doped white OLEDs

Kim, Hakjo; Kim, Hyeonji; Kim, Seung Chan; Lee, Jun Yeob; Kang, Youngjin

doi:10.1016/j.dyepig.2023.111717

Cited by 1 publication

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“…Considering the aforementioned criteria for achieving blue emission, bipyridine derivatives with C^N chelation modes are highly recommended ligands. They exhibit high triplet energies and quantum efficiencies when metallated with heavy Ir(III) or Pt(II) ions [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. However, examples of tetradentate ligand production through the combination of bipyridine and carbazole are extremely rare.…”

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confidence: 99%

Blue Phosphorescent Pt(II) Compound Based on Tetradentate Carbazole/2,3′-Bipyridine Ligand and Its Application in Organic Light-Emitting Diodes

Kim,

Ryu,

Hong

et al. 2024

Molecules

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The tetradentate ligand, merging a carbazole unit with high triplet energy and dimethoxy bipyridine, renowned for its exceptional quantum efficiency in coordination with metals like Pt, is expected to demonstrate remarkable luminescent properties. However, instances of tetradentate ligands such as bipyridine-based pyridylcarbazole derivatives remain exceptionally scarce in the current literature. In this study, we developed a tetradentate ligand based on carbazole and 2,3′-bipyridine and successfully complexed it with Pt(II) ions. This novel compound (1) serves as a sky-blue phosphorescent material for use in light-emitting diodes. Based on single-crystal X-ray analysis, compound 1 has a distorted square-planar geometry with a 5/6/6 backbone around the Pt(II) core. Bright sky-blue emissions were observed at 488 and 516 nm with photoluminescent quantum yields of 34% and a luminescent lifetime of 2.6 μs. TD-DFT calculations for 1 revealed that the electronic transition was mostly attributed to the ligand-centered (LC) charge transfer transition with a small contribution from the metal-to-ligand charge transfer transition (MLCT, ~14%). A phosphorescent organic light-emitting device was successfully fabricated using this material as a dopant, along with 3′-di(9H-carbazol-9-yl)-1,1′-biphenyl (mCBP) and 9-(3′-carbazol-9-yl-5-cyano-biphenyl-3-yl)-9H-carbazole-3-carbonitrile (CNmCBPCN) as mixed hosts. A maximum quantum efficiency of 5.2% and a current efficiency of 15.5 cd/A were obtained at a doping level of 5%.

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