Enhancing the Luminescence Efficiency of Blue Phosphorescent Organic Light‐Emitting Diodes: Constructing Platinum(II) Complexes with a Functionalized Tetradentate Ligand

Ryu, Chan Hee; Jo, Unhyeok; Shin, Ilsup; Kim, Mingi; Cheong, Kiun; Bin, Jong‐Kwan; Lee, Jun Yeob; Lee, Kang Mun

doi:10.1002/adom.202303109

Cited by 5 publications

(1 citation statement)

References 25 publications

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“…Recently, there has been significant interest in blue and sky-blue phosphorescent platinum complexes featuring tetradentate ligands. This interest is primarily because of their excellent performance in organic light-emitting devices (OLEDs), characterized by high external quantum efficiency (EQE) and long operational lifetimes [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. The complexation of Pt(II) ions with tetradentate ligands results in the formation of five- or six-membered metallacycles.…”

Section: Introductionmentioning

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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Section: Introductionmentioning

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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Blue‐Emitting Iridium(III) Carbene Phosphors with Suppressed Efficiency Roll‐Off and Enhanced Durability of Hyper‐OLED Devices

Yan,

Wu,

Yiu

et al. 2024

Advanced Optical Materials

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OLED technology has been long hampered by the slow progress of efficient and durable blue phosphors. To circumvent this issue, a novel imidazo[4,5‐b]pyrazin‐2‐ylidene chelate with both the bulky tert‐butyl and 2,6‐dimethylphenyl appendages is rationally employed in synthesizing Ir(III) carbene phosphors f‐ct8c and f‐ct8d. Installation of bulky groups at the proper location not only reduces the anticipated product isomers to two, but also improves the photophysical efficiency of these Ir(III) emitters. Notably, these emitters exhibited blue photoluminescence with excellent quantum yields and short radiative lifetimes. One device with assistant sensitizer f‐ct8c at 10 wt% and terminal emitter ν‐DABNA at 1 wt% has successfully achieved a remarkable EQEmax of 30.5%, CIExy chromaticity of (0.129, 0.079), confirming the generation of exceptional blue hyperphosphorescence. Moreover, the same emitter f‐ct8c co‐doped in exciplex co‐host of SiCzCz: SiTrzCz2 afforded EQEmax of 28.4% and EQE of 23.6% at practical luminance of 1000 cd m‒2, respectively, together with max. luminance exceeding 27000 cd m‒2. A long operational lifetime LT50 of 309 h is obtained for f‐ct8d at an initial brightness of 500 cd m‒2, affirming the improved efficiency and stability of the molecular designs.

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Improving the Blue Color Purity of Tetradentate Pt(II) Complexes with the Assistance of F⋅⋅⋅H Interaction towards High‐Performance Blue Phosphorescent OLEDs with EQE over 33 %

Zhu,

Huang,

Zhang

et al. 2024

Angewandte Chemie

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Among the various challenges in the field of organic light‐emitting diodes (OLEDs), simultaneously achieving high efficiency, a long lifespan, and a narrow full‐width at half maximum (FWHM) in blue OLEDs remains a significant hurdle. Herein, we demonstrate a strategy to improve the color purity of tetradentate Pt(II) complexes with the assistance of F···H interaction by incorporating trifluoromethyl (‐CF3) groups into the well‐known blue tetradentate Pt(II) phosphorescent complex. The results show that the different substitution positions of ‐CF3 have significantly varying effects on the FWHM values of the complexes; specifically, introducing ‐CF3 on the benzene ring of carbazole effectively reduces the FWHM, while introducing it on the benzene ring linked to the carbene unit has a minimal impact. When utilized in a mixed host system of SiCzCz/SiTrzCz2, the OLEDs with these new complexes as emitters demonstrated maximum external quantum efficiencies (EQEs) of 27.1%, 33.8%, and 27.6% for PtON‐CF3‐1, PtON‐CF3‐2, and PtON‐2CF3, respectively, with excellent color purity (CIEy ≈ 0.14 for the PtON‐CF3‐2 based device). Notably, the device based on PtON‐CF3‐2 matched the stability of the benchmark PtON‐TBBI complex.This work offers an important guideline for the design of high efficient Pt(II) phosphorescent complexes with good blue color purity.

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Enhancing the Luminescence Efficiency of Blue Phosphorescent Organic Light‐Emitting Diodes: Constructing Platinum(II) Complexes with a Functionalized Tetradentate Ligand

Cited by 5 publications

References 25 publications

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

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

Blue‐Emitting Iridium(III) Carbene Phosphors with Suppressed Efficiency Roll‐Off and Enhanced Durability of Hyper‐OLED Devices

Improving the Blue Color Purity of Tetradentate Pt(II) Complexes with the Assistance of F⋅⋅⋅H Interaction towards High‐Performance Blue Phosphorescent OLEDs with EQE over 33 %

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