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Efficient and stable single-layer organic light-emitting diodes based on thermally activated delayed fluorescence


From a design, optimization and fabrication perspective, an organic light-emitting diode consisting of only one single layer of a neat semiconductor would be highly attractive. Here, we demonstrate an efficient and stable organic light-emitting diode based on a single layer of a neat thermally activated delayed fluorescence emitter. By employing ohmic electron and hole contacts, charge injection is efficient and the absence of heterojunctions results in an exceptionally low operating voltage of 2.9 V at a luminance of 10,000 cd m−2. Balanced electron and hole transport results in a maximum external quantum efficiency of 19% at 500 cd m−2 and a broadened emission zone, which greatly improves the operational stability, allowing a lifetime to 50% of the initial luminance of 1,880 h for an initial luminance of 1,000 cd m−2. As a result, this single-layer concept combines high power efficiency with long lifetime in a simplified architecture, rivalling and even exceeding the performance of complex multilayer devices.

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Fig. 1: Device layout and molecular structure of the TADF emitter CzDBA.
Fig. 2: Charge transport in CzDBA and simulated recombination profile.
Fig. 3: Device performance of single-layer CzDBA OLEDs.
Fig. 4: Operational lifetime of single-layer CzDBA OLEDs.
Fig. 5: Ambient stability of a single-layer CzDBA OLED.

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.


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

    Article  ADS  Google Scholar 

  2. Burroughes, J. H. et al. Light-emitting diodes based on conjugated polymers. Nature 347, 539–541 (1990).

    Article  ADS  Google Scholar 

  3. Blom, P. W. M., De Jong, M. J. M. & Vleggaar, J. J. M. Electron and hole transport in poly(p-phenylene vinylene) devices. Appl. Phys. Lett. 68, 3308–3310 (1996).

    Article  ADS  Google Scholar 

  4. Nicolai, H. T. et al. Unification of trap-limited electron transport in semiconducting polymers. Nat. Mater. 11, 882–887 (2012).

    Article  ADS  Google Scholar 

  5. Kuik, M., Koster, L. J. A., Dijkstra, A. G., Wetzelaer, G. A. H. & Blom, P. W. M. Non-radiative recombination losses in polymer light-emitting diodes. Org. Electron. 13, 969–974 (2012).

    Article  Google Scholar 

  6. Kido, J., Kimura, M. & Nagai, K. Multilayer white light-emitting organic electroluminescent device. Science 267, 1332–1334 (1995).

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  8. Adachi, C. et al. Nearly 100% internal phosphorescence efficiency in an organic light-emitting device. J. Appl. Phys. 90, 5048–5051 (2001).

    Article  ADS  Google Scholar 

  9. Pfeiffer, M., Forrest, S. R., Leo, K. & Thompson, M. E. Electrophosphorescent p–i–n organic light emitting devices for very high efficiency flat panel displays. Adv. Mater. 14, 1633–1636 (2002).

    Article  Google Scholar 

  10. He, G. et al. High-efficiency and low-voltage p–i–n electrophosphorescent organic light-emitting diodes with double-emission layers. Appl. Phys. Lett. 85, 3911–3913 (2004).

    Article  ADS  Google Scholar 

  11. Walzer, K., Maennig, B., Pfeiffer, M. & Leo, K. Highly efficient organic devices based on electrically doped transport layers. Chem. Rev. 107, 1233–1271 (2007).

    Google Scholar 

  12. Uoyama, H., Goushi, K., Shizu, K., Nomura, H. & Adachi, C. Highly efficient organic light-emitting diodes from delayed fluorescence. Nature 492, 234–238 (2012).

    Article  ADS  Google Scholar 

  13. Liu, Y., Li, C., Ren, Z., Yan, S. & Bryce, M. R. All-organic thermally activated delayed fluorescence materials for organic light-emitting diodes. Nat. Rev. Mater. 3, 18020 (2018).

    Article  ADS  Google Scholar 

  14. Cui, L.-S. et al. Long-lived efficient delayed fluorescence organic light-emitting diodes using n-type hosts. Nat. Commun. 8, 2250 (2017).

    Article  ADS  Google Scholar 

  15. Zhang, Q. et al. Nearly 100% internal quantum efficiency in undoped electroluminescent devices employing pure organic emitters. Adv. Mater. 27, 2096–2100 (2015).

    Article  Google Scholar 

  16. Kotadiya, N. B. et al. Universal strategy for ohmic hole injection into organic semiconductors with high ionization energies. Nat. Mater. 17, 329–334 (2018).

    Article  ADS  Google Scholar 

  17. Wu, T.-L. et al. Diboron compound-based organic light-emitting diodes with high efficiency and reduced efficiency roll-off. Nat. Photon. 12, 235–240 (2018).

    Article  ADS  Google Scholar 

  18. Zhou, M. et al. Effective work functions for the evaporated metal/organic semiconductor contacts from in-situ diode flatband potential measurements. Appl. Phys. Lett. 101, 013501 (2012).

    Article  ADS  Google Scholar 

  19. Kao, K.-C. & Hwang, W. Electrical Transport in Solids (Pergamon Press, 1981).

  20. Koster, L. J. A., Smits, E. C. P., Mihailetchi, V. D. & Blom, P. W. M. Device model for the operation of polymer/fullerene bulk heterojunction solar cells. Phys. Rev. B 72, 085205 (2005).

    Article  ADS  Google Scholar 

  21. Shirota, Y. & Kageya, H. Chem. Rev. 107, 953–1010 (2007).

    Article  Google Scholar 

  22. Kuik, M. et al. Charge transport and recombination in polymer light-emitting diodes. Adv. Mater. 26, 512–531 (2014).

    Article  Google Scholar 

  23. Giebink, N. C. et al. Intrinsic luminance loss in phosphorescent small-molecule organic light-emitting diodes due to bimolecular annihilation reactions. J. Appl. Phys. 103, 044509 (2008).

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  25. Kim, J.-M., Lee, C.-H. & Kim, J.-J. Mobility balance in the light-emitting layer governs the polaron accumulation and operational stability of organic light-emitting diodes. Appl. Phys. Lett. 111, 203301 (2017).

    Article  ADS  Google Scholar 

  26. Niu, Q., Rohloff, R., Wetzelaer, G.-J. A. H., Blom, P. W. M. & Crăciun, N. I. Hole trap formation in polymer light-emitting diodes under current stress. Nat. Mater. 17, 557–562 (2018).

    Article  ADS  Google Scholar 

  27. Meerheim, R., Furno, M., Hofmann, S., Lüssem, B. & Leo, K. Quantification of energy loss mechanisms in organic light-emitting diodes. Appl. Phys. Lett. 97, 253305 (2010).

    Article  ADS  Google Scholar 

  28. De Bruyn, P., van Rest, A. H. P., Wetzelaer, G. A. H., de Leeuw, D. M. & Blom, P. W. M. Diffusion-limited current in organic metal–insulator–metal diodes. Phys. Rev. Lett. 111, 186801 (2013).

    Article  ADS  Google Scholar 

  29. Meerheim, R., Walzer, K., He, G., Pfeiffer, M. & Leo, K. Highly efficient organic light emitting diodes (OLED) for diplays and lighting. Proc. SPIE 6192, 61920P (2006).

    Article  ADS  Google Scholar 

  30. Sasabe, H. et al. Extremely low operating voltage green phosphorescent organic light-emitting devices. Adv. Funct. Mater. 23, 5550–5555 (2013).

    Article  Google Scholar 

  31. Zhang, D. D., Qiao, J., Zhang, D. Q. & Duan, L. Ultrahigh‐efficiency green PHOLEDs with a voltage under 3 V and a power efficiency of nearly 110 lm W−1 at luminance of 10,000 cd m−2. Adv. Mater. 29, 1702847 (2017).

    Article  Google Scholar 

  32. Sasabe, H. et al. Ultrahigh power efficiency thermally activated delayed fluorescent OLEDs by the strategic use of electron-transport materials. Adv. Opt. Mater. 6, 1800376 (2018).

    Article  Google Scholar 

  33. Seino, Y., Inomata, S., Sasabe, H., Pu, Y.-J. & Kido, J. High-performance green OLEDs using thermally activated delayed fluorescence with a power efficiency of over 100 lm W−1. Adv. Mater. 28, 2638–2643 (2016).

    Article  Google Scholar 

  34. Schaer, M., Nuesch, F., Berner, D., Leo, W. & Zuppiroli, L. Water vapor and oxygen degradation mechanisms in organic light emitting diodes. Adv. Funct. Mater. 11, 116–121 (2001).

    Article  Google Scholar 

  35. Van de Weijer, P., Lu, K., de Winter, S. H. P. M., Janssen, R. R. & Akkerman, H. B. Mechanism of the operational effect of black spot growth in OLEDs. Org. Electron. 37, 155–162 (2016).

    Article  Google Scholar 

  36. Phatak, R., Tsui, T. Y. & Aziz, H. Dependence of dark spot growth on cathode/organic interfacial adhesion in organic light emitting devices. J. Appl. Phys. 111, 054512 (2012).

    Article  ADS  Google Scholar 

  37. De Bruyn, P., Moet, D. J. D. & Blom, P. W. M. All-solution processed polymer light-emitting diodes with air stable metal-oxide electrodes. Org. Electron. 13, 1023–1030 (2012).

    Article  Google Scholar 

  38. Tang, S. et al. Design rules for light-emitting electrochemical cells delivering bright luminance at 27.5 percent external quantum efficiency. Nat. Commun. 8, 1190 (2017).

    Article  ADS  Google Scholar 

  39. Godumala, M., Choi, S., Cho, M. J. & Choi, D. H. Recent breakthroughs in thermally activated delayed fluorescence organic light emitting diodes containing non-doped emitting layers. J. Mater. Chem. C 7, 2172–2198 (2019).

    Article  Google Scholar 

  40. Silvestre, G. C. M., Johnson, M. T., Giraldo, A. & Shannon, J. M. Light degradation and voltage drift in polymer light-emitting diodes. Appl. Phys. Lett. 78, 1619–1621 (2001).

    Article  ADS  Google Scholar 

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

    Article  Google Scholar 

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We thank C. Bauer, H.-J. Guttmann and F. Keller for technical support and Y. Ie for the synthesis of 4CzIPN. This project has received funding from the European Union Horizon 2020 research and innovation programme under grant agreement no. 646176 (EXTMOS).

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Authors and Affiliations



G.-J.A.H.W. proposed the project. G.-J.A.H.W. and N.B.K. designed the experiments. N.B.K. carried out device fabrication and measurements. G.-J.A.H.W. performed simulations. G.-J.A.H.W. and P.W.M.B. supervised the project and wrote the manuscript.

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Correspondence to Gert-Jan A. H. Wetzelaer.

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Molecular structures and optoelectronic characterization.

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Kotadiya, N.B., Blom, P.W.M. & Wetzelaer, GJ.A.H. Efficient and stable single-layer organic light-emitting diodes based on thermally activated delayed fluorescence. Nat. Photonics 13, 765–769 (2019).

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