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Efficient and stable organic light-emitting devices employing phosphorescent molecular aggregates

Nature Photonics volume 15, pages 230–237 (2021)Cite this article

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Abstract

Stable and efficient organic light-emitting diodes (OLEDs) operating at high brightness are desirable for future high-resolution displays and lighting products. Here, we report a tetradentate Pd(ii) complex called Pd3O8-P, which has attractive optoelectronics properties. At room temperature, aggregates of Pd3O8-P exhibited a close-to-unity photoluminescent quantum yield and a short transient lifetime of 0.62 μs. A host-free Pd3O8-P yellow-orange OLED emitted light with a peak at 588 nm, a half-bandwidth of 84 nm and CIE coordinates of (0.52, 0.47), and achieved a peak external quantum efficiency (EQE) of 34.8%. The device had reduced efficiency roll-off, retaining high EQEs of 33.5% at 1,000 cd m−2 and 29.5% at 10,000 cd m−2. The estimated operational half-lifetime was 9.59 million hours at 1,000 cd m−2. The fact that the tetradentate metal complex has a triplet in the blue-emitting region may also assist the development of efficient and long-lived blue OLEDs in the future.

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Fig. 1: Photophysical study of Pd3O8-P in solution and thin film.
Fig. 2: Qualitative molecular orbital schemes for Pd3O8-P and its aggregate, and analysis of horizontal emitting dipole orientation ratios for Pd3O8-P aggregates.
Fig. 3: Performance of the OLEDs.
Fig. 4: Operational stability of OLEDs.

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Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

References

  1. Tang, C. W. & VanSlyke, S. A. Organic electroluminescent diodes. Appl. Phys. Lett. 51, 913–915 (1987).

    ADS  Google Scholar 

  2. Baldo, M. A. et al. Highly efficient phosphorescent emission from organic electroluminescent devices. Nature 395, 151–154 (1998).

    ADS  Google Scholar 

  3. Fleetham, T. B., Huang, L., Klimes, K., Brooks, J. & Li, J. Tetradentate Pt(ii) complexes with 6-membered chelate rings: a new route for stable and efficient blue organic light emitting diodes. Chem. Mater. 28, 3276–3282 (2016).

    Google Scholar 

  4. Lee, J. et al. Deep blue phosphorescent organic light-emitting diodes with very high brightness and efficiency. Nat. Mater. 15, 92–98 (2016).

    ADS  Google Scholar 

  5. Fleetham, T., Li, G. & Li, J. Phosphorescent Pt(ii) and Pd(ii) complexes for efficient, high-color-quality, and stable OLEDs. Adv. Mater. 29, 1601861 (2017).

    Google Scholar 

  6. Tuong, Ly,K. et al. Near-infrared organic light-emitting diodes with very high external quantum efficiency and radiance. Nat. Photon. 11, 63–68 (2017).

    ADS  Google Scholar 

  7. Zhang, Q. et al. Efficient blue organic light-emitting diodes employing thermally activated delayed fluorescence. Nat. Photon. 8, 326–332 (2014).

    ADS  Google Scholar 

  8. Hua, H., Hu, X. & Gao, C. A high-resolution optical see-through head-mounted display with eyetracking capability. Opt. Express 21, 30993–30998 (2013).

    ADS  Google Scholar 

  9. D’Andrade, B. W. & Forrest, S. R. White organic light-emitting devices for solid-state lighting. Adv. Mater. 16, 1585–1595 (2004).

    Google Scholar 

  10. So, F., Kido, J. & Burrows, P. Organic light-emitting devices for solid-state lighting. MRS Bull. 33, 663–669 (2008).

    Google Scholar 

  11. Baldo, M. A., Adachi, C. & Forrest, S. R. Transient analysis of organic electrophosphorescence. II. Transient analysis of triplet–triplet annihilation. Phys. Rev. B 62, 10967–10977 (2000).

    ADS  Google Scholar 

  12. Reineke, S., Walzer, K. & Leo, K. Triplet–exciton quenching in organic phosphorescent light-emitting diodes with Ir-based emitters. Phys. Rev. B 75, 125328 (2007).

    ADS  Google Scholar 

  13. Murawski, C., Leo, K. & Gather, M. C. Efficiency roll-off in organic light-emitting diodes. Adv. Mater. 25, 6801–6827 (2013).

    Google Scholar 

  14. Lee, J. et al. Hot excited state management for long-lived blue phosphorescent organic light-emitting diodes. Nat. Commun. 8, 15566 (2017).

    ADS  Google Scholar 

  15. Coburn, C., Lee, J. & Forrest, S. R. Charge balance and exciton confinement in phosphorescent organic light emitting diodes. Adv. Opt. Mater. 4, 889–895 (2016).

    Google Scholar 

  16. Zhang, Y., Lee, J. & Forrest, S. R. Tenfold increase in the lifetime of blue phosphorescent organic light-emitting diodes. Nat. Commun. 5, 5008 (2014).

    ADS  Google Scholar 

  17. Su, S.-J., Gonmori, E., Sasabe, H. & Kido, J. Highly efficient organic blue-and white-light-emitting devices having a carrier- and exciton-confining structure for reduced efficiency roll-off. Adv. Mater. 20, 4189–4194 (2008).

    Google Scholar 

  18. Park, Y.-S. et al. Exciplex-forming co-host for organic light-emitting diodes with ultimate efficiency. Adv. Funct. Mater. 23, 4914–4920 (2013).

    Google Scholar 

  19. Klimes, K., Zhu, Z.-Q. & Li, J. Efficient blue phosphorescent OLEDs with improved stability and color purity through judicious triplet exciton management. Adv. Funct. Mater. 29, 1903068 (2019).

    Google Scholar 

  20. Lee, S., Kim, K.-H., Limbach, D., Park, Y.-S. & Kim, J.-J. Low roll-off and high efficiency orange organic light emitting diodes with controlled co-doping of green and red phosphorescent dopants in an exciplex forming co-host. Adv. Funct. Mater. 23, 4105–4110 (2013).

    Google Scholar 

  21. Gong, S. et al. Bipolar tetraarylsilanes as universal hosts for blue, green, orange, and white electrophosphorescence with high efficiency and low efficiency roll-off. Adv. Funct. Mater. 21, 1168–1178 (2011).

    Google Scholar 

  22. Kawamura, Y., Brooks, J., Brown, J. J., Sasabe, H. & Adachi, C. Intermolecular interaction and a concentration-quenching mechanism of phosphorescent Ir(iii) complexes in a solid film. Phys. Rev. Lett. 96, 017404 (2006).

    ADS  Google Scholar 

  23. Holmes, R. J. et al. Reduced geminate recombination in iridium-based electrophosphorescent materials. Org. Electron. 7, 163–172 (2006).

    Google Scholar 

  24. Kim, K.-H. et al. Crystal organic light-emitting diodes with perfectly oriented non-doped Pt-based emitting layer. Adv. Mater. 28, 2526–2532 (2016).

    Google Scholar 

  25. Li, G., Fleetham, T. & Li, J. Efficient and stable white organic light-emitting diodes employing a single emitter. Adv. Mater. 26, 2931–2936 (2014).

    Google Scholar 

  26. Fleetham, T., Huang, L. & Li, J. Tetradentate platinum complexes for efficient and stable excimer-based white OLEDs. Adv. Funct. Mater. 24, 6066–6073 (2014).

    Google Scholar 

  27. Fleetham, T., Ecton, J., Wang, Z., Bakken, N. & Li, J. Single-doped white organic light-emitting device with an external quantum efficiency over 20%. Adv. Mater. 25, 2573–2576 (2013).

    Google Scholar 

  28. Ganesan, P. et al. Functional pyrimidinyl pyrazolate Pt(ii) complexes: role of nitrogen atom in tuning the solid-state stacking and photophysics. Adv. Funct. Mater. 29, 1900923 (2019).

    Google Scholar 

  29. Wang, Q. et al. A non-doped phosphorescent organic light-emitting device with above 31% external quantum efficiency. Adv. Mater. 26, 8107–8113 (2014).

    Google Scholar 

  30. Fleetham, T., Ji, Y., Huang, L., Fleetham, T. S. & Li, J. Efficient and stable single-doped white OLEDs using a palladium-based phosphorescent excimer. Chem. Sci. 8, 7983–7990 (2017).

    Google Scholar 

  31. Chow, P. K. et al. Strongly phosphorescent palladium(ii) complexes of tetradentate ligands with mixed oxygen, carbon and nitrogen donor atoms: photophysics, photochemistry and applications. Angew. Chem. Int. Ed. 52, 11775–11779 (2013).

    Google Scholar 

  32. Yersin, H., Rausch, A. F., Czerwieniec, R., Hofbeck, T. & Fischer, T. The triplet state of organo-transition metal compounds. Triplet harvesting and singlet harvesting for efficient OLEDs. Coord. Chem. Rev. 255, 2622–2652 (2011).

    Google Scholar 

  33. Li, G., Wolfe, A., Brooks, J., Zhu, Z.-Q. & Li, J. Modifying emission spectral bandwidth of phosphorescent platinum(ii) complexes through synthetic control. Inorg. Chem. 56, 8244–8256 (2017).

    Google Scholar 

  34. Lamansky, S. et al. Synthesis and characterization of phosphorescent cyclometalated iridium complexes. Inorg. Chem. 40, 1704–1711 (2001).

    Google Scholar 

  35. Díez, Á. et al. Structural and luminescence studies on π···π and Pt···Pt interactions in mixed chloro-isocyanide cyclometalated platinum(ii) complexes. Inorg. Chem. 49, 3239–3251 (2010).

    Google Scholar 

  36. Ma, B., Djurovich, P. I. & Thompson, M. E. Excimer and electron transfer quenching studies of a cyclometalated platinum complex. Coord. Chem. Rev. 249, 1501–1510 (2005).

    Google Scholar 

  37. Chan, K. H.-Y., Chow, H.-S., Wong, K. M.-C., Yeung, M. C.-L. & Yam, V. W.-W. Towards thermochromic and thermoresponsive near-infrared (NIR) luminescent molecular materials through the modulation of inter- and/or intramolecular Pt⋯Pt and π–π interactions. Chem. Sci. 1, 477–482 (2010).

    Google Scholar 

  38. Lai, S.-W. et al. Luminescent mononuclear and binuclear cyclometalated palladium(ii) complexes of 6-phenyl-2,2′-bipyridines: spectroscopic and structural comparisons with platinum(ii) analogues. Inorg. Chem. 39, 255–262 (2000).

    Google Scholar 

  39. Lu, W. et al. Structural and spectroscopic studies on Pt···Pt and π–π interactions in luminescent multinuclear cyclometalated platinum(ii) homologues tethered by oligophosphine auxiliaries. J. Am. Chem. Soc. 126, 7639–7651 (2004).

    Google Scholar 

  40. Ma, B. et al. Synthetic control of Pt···Pt separation and photophysics of binuclear platinum complexes. J. Am. Chem. Soc. 127, 28–29 (2005).

    Google Scholar 

  41. Kim, D. & Brédas, J.-L. Triplet excimer formation in platinum-based phosphors: a theoretical study of the roles of Pt–Pt bimetallic interactions and interligand π–π interactions. J. Am. Chem. Soc. 131, 11371–11380 (2009).

    Google Scholar 

  42. Kim, K.-H. & Kim, J.-J. Origin and control of orientation of phosphorescent and TADF dyes for high-efficiency OLEDs. Adv. Mater. 30, 1705600 (2018).

    ADS  Google Scholar 

  43. D’Andrade, B. & Forrest, S. R. Formation of triplet excimers and dimers in amorphous organic thin films and light emitting devices. Chem. Phys. 286, 321–335 (2003).

    Google Scholar 

  44. Zhu, Z.-Q., Park, C.-D., Klimes, K. & Li, J. Highly efficient blue OLEDs based on metal-assisted delayed fluorescence Pd(ii) complexes. Adv. Opt. Mater. 7, 1801518 (2019).

    Google Scholar 

  45. Lee, J. et al. Down-conversion white organic light-emitting diodes using microcavity structure. Adv. Energy Mater. 1, 174–178 (2011).

    Google Scholar 

  46. Sun, Y. & Forrest, S. R. Enhanced light out-coupling of organic light-emitting devices using embedded low-index grids. Nat. Photon. 2, 483–487 (2008).

    Google Scholar 

  47. Do, Y. R. et al. Enhanced light extraction from organic light-emitting diodes with 2D SiO2/SiNx photonic crystals. Adv. Mater. 15, 1214–1218 (2003).

    Google Scholar 

  48. Youn, W., Lee, J., Xu, M., Singh, R. & So, F. Corrugated sapphire substrates for organic light-emitting diode light extraction. ACS Appl. Mater. Interfaces 7, 8974–8978 (2015).

    Google Scholar 

  49. Qu, Y., Slootsky, M. & Forrest, S. R. Enhanced light extraction from organic light-emitting devices using a sub-anode grid. Nat. Photon. 9, 758–763 (2015).

    ADS  Google Scholar 

  50. Zhu, Z.-Q., Klimes, K., Holloway, S. & Li, J. Efficient cyclometalated platinum(ii) complex with superior operational stability. Adv. Mater. 29, 1605002 (2017).

    Google Scholar 

  51. Zhu, Z.-Q., Fleetham, T., Turner, E. & Li, J. Harvesting all electrogenerated excitons through metal assisted delayed fluorescent materials. Adv. Mater. 27, 2533–2537 (2015).

    Google Scholar 

  52. Féry, C., Racine, B., Vaufrey, D., Doyeux, H. & Cinà, S. Physical mechanism responsible for the stretched exponential decay behavior of aging organic light-emitting diodes. Appl. Phys. Lett. 87, 213502 (2005).

    ADS  Google Scholar 

  53. Nakanotani, H., Masui, K., Nishide, J., Shibata, T. & Adachi, C. Promising operational stability of high-efficiency organic light-emitting diodes based on thermally activated delayed fluorescence. Sci. Rep. 3, 2127 (2013).

    ADS  Google Scholar 

  54. Seo, S. et al. Exciplex–triplet energy transfer: a new method to achieve extremely efficient organic light-emitting diode with external quantum efficiency over 30% and drive voltage below 3 V. Jpn J. Appl. Phys. 53, 042102 (2014).

    ADS  Google Scholar 

  55. Qian, L., Zheng, Y., Xue, J. & Holloway, P. H. Stable and efficient quantum-dot light-emitting diodes based on solution-processed multilayer structures. Nat. Photon. 5, 543–548 (2011).

    ADS  Google Scholar 

  56. Li, L.-K. et al. Strategies towards rational design of gold(iii) complexes for high-performance organic light-emitting devices. Nat. Photon. 13, 185–191 (2019).

    ADS  Google Scholar 

  57. Forrest, S. R., Bradley, D. D. C. & Thompson, M. E. Measuring the efficiency of organic light-emitting devices. Adv. Mater. 15, 1043–1048 (2003).

    Google Scholar 

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Acknowledgements

We thank the Department of Energy (contracts EE0007090 and EE0008721) and Universal Display Corporation for partial support of this work.

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  1. These authors contributed equally: Linyu Cao, Kody Klimes.

Authors and Affiliations

  1. Materials Science and Engineering, Arizona State University, Tempe, AZ, USA

    Linyu Cao, Kody Klimes, Yunlong Ji & Jian Li

  2. Universal Display Corporation, Ewing, NJ, USA

    Tyler Fleetham

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Contributions

J.L. designed and supervised this research. L.C. and Y.J. conducted the synthesis and characterization of the Pd(ii) complex. K.K., L.C. and T.F. carried out device fabrication and measurements. L.C., T.F. and J.L. contributed to the manuscript.

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Correspondence to Jian Li.

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Supplementary materials and regents, synthesis of ligand 3O8-P and Figs. 1–8.

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Cao, L., Klimes, K., Ji, Y. et al. Efficient and stable organic light-emitting devices employing phosphorescent molecular aggregates. Nat. Photonics 15, 230–237 (2021). https://doi.org/10.1038/s41566-020-00734-2

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