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Exceptionally stable blue phosphorescent organic light-emitting diodes

Abstract

Blue phosphorescent organic light-emitting diodes (PhOLEDs) can deliver superior electroluminescence efficiencies than blue fluorescent OLEDs; however, their commercial debut has been delayed by short device lifetimes, especially for deep-blue PhOLEDs with Commission International de l’Eclairage y co-ordinates of less than 0.20. Here we report the use of new dopant and host materials to create a blue PhOLED device with a y co-ordinate of 0.197 and a long device lifetime of LT70 = 1,113 h [Initial luminance (L0) = 1,000 cd m–2]. Introducing bulky 3,5-di-tert-butyl-phenyl into the N-heterocyclic carbene moiety in the Pt(II) complex enhanced the photochemical stability of the high-lying metal-centred triplet state and prevented undesirable host–guest interactions, contributing to a longer device lifetime and higher colour purity. For the exciplex-forming host, the hole-transporting and electron-transporting host materials utilized a triphenylsilyl group for enhanced stability, which also improved the device lifetime.

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Fig. 1: Synthesis, spectrum and transient decay of the dopants.
Fig. 2: Chemical structure, frontier orbitals and exciplex characteristics of the host materials.
Fig. 3: Device performance of PhOLEDs.
Fig. 4: Intrinsic stability.

Data availability

The data that support the findings of this study are available from the corresponding authors on reasonable request. All data generated or analysed during this study are included in this published article and its Supplementary Information.

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Acknowledgements

Y.Y. (Ewha Womans’ Univ.) acknowledges the Midcareer Research Program (NRF-2019R1A2C2003969), the Basic Research Laboratory Program (NRF-2019R1A4A1029052) and the Nano Material Technology Development Program (NRF-2021M3D1A2049323) through the National Research Foundation grants funded by the Ministry of Science, Information and Communication Technology, and Future Planning of Korea.

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Contributions

J.S., S.K., S.-B.K., H.A., D.S. and Y.Y. analysed the data and wrote the manuscript under supervision of C.C. and S.K., J.S., Y.L. and S.-B.K. designed the dopant molecule. S.-B.K. and S.K. synthesized and characterized the dopant material. H.A. designed the host molecule. H.U. and H.A. synthesized and characterized the host materials under supervision of S.-H.H. J.S. performed exciplex analysis. S.K. conducted theoretical calculations for all of the materials. J.S. and Y.L. analysed the device data. P.J. carried out device fabrication. Y.Y. coordinated the research at Ewha Womans University. D.S. performed the degradation experiments. All authors discussed the progress of research and reviewed the manuscript.

Corresponding authors

Correspondence to Changwoong Chu or Sunghan Kim.

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Nature Photonics thanks Marc Baldo, Jian Li and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Synthesis, Experimental, Methods for Device fabrication and measurements, Supplementary Figs. 1–26, Tables 1–9 and References.

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Sun, J., Ahn, H., Kang, S. et al. Exceptionally stable blue phosphorescent organic light-emitting diodes. Nat. Photon. 16, 212–218 (2022). https://doi.org/10.1038/s41566-022-00958-4

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