Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Molecular-scale simulation of electroluminescence in a multilayer white organic light-emitting diode

Nature Materials volume 12, pages 652–658 (2013)Cite this article

Subjects

Abstract

In multilayer white organic light-emitting diodes the electronic processes in the various layers—injection and motion of charges as well as generation, diffusion and radiative decay of excitons—should be concerted such that efficient, stable and colour-balanced electroluminescence can occur. Here we show that it is feasible to carry out Monte Carlo simulations including all of these molecular-scale processes for a hybrid multilayer organic light-emitting diode combining red and green phosphorescent layers with a blue fluorescent layer. The simulated current density and emission profile are shown to agree well with experiment. The experimental emission profile was obtained with nanometre resolution from the measured angle- and polarization-dependent emission spectra. The simulations elucidate the crucial role of exciton transfer from green to red and the efficiency loss due to excitons generated in the interlayer between the green and blue layers. The perpendicular and lateral confinement of the exciton generation to regions of molecular-scale dimensions revealed by this study demonstrate the necessity of molecular-scale instead of conventional continuum simulation.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Get just this article for as long as you need it

$39.95

Learn more

Prices may be subject to local taxes which are calculated during checkout

Figure 1: OLED stack and its electrical characteristics.
Figure 2: Light-emission and exciton-generation profiles.
Figure 3: Energy-level diagram.
Figure 4: Inhomogeneity in exciton generation.
Figure 5: Spatial distribution of exciton generation.

References

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

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  4. Reineke, S. et al. White organic light-emitting diodes with fluorescent tube efficiency. Nature 459, 234–239 (2009).

    Article  CAS  Google Scholar 

  5. Schwartz, G., Fehse, K., Pfeiffer, M., Walzer, K. & Leo, K. Highly efficient white organic light emitting diodes comprising an interlayer to separate fluorescent and phosphorescent regions. Appl. Phys. Lett. 89, 083509 (2006).

    Article  Google Scholar 

  6. Reineke, S. & Baldo, M. Recent progress in the understanding of exciton dynamics within phosphorescent OLEDs. Phys. Status Solidi A 209, 2341–2353 (2012).

    Article  CAS  Google Scholar 

  7. Bässler, H. & Köhler, A. Charge transport in organic semiconductors. Top. Curr. Chem. 312, 1–66 (2012).

    Google Scholar 

  8. Pasveer, W. F. et al. Unified description of charge-carrier mobilities in disordered semiconducting polymers. Phys. Rev. Lett. 94, 206601 (2005).

    Article  CAS  Google Scholar 

  9. Bouhassoune, M., Van Mensfoort, S. L. M., Bobbert, P. A. & Coehoorn, R. Carrier-density and field-dependent charge-carrier mobility in organic semiconductors with correlated Gaussian disorder. Org. Elec. 10, 437–445 (2009).

    Article  CAS  Google Scholar 

  10. Schober, M. et al. Quantitative description of charge-carrier transport in a white organic light-emitting diode. Phys. Rev. B 84, 165326 (2011).

    Article  Google Scholar 

  11. Van Mensfoort, S. L. M. et al. Predictive modeling of the current density and radiative recombination in blue polymer-based light-emitting diodes. J. Appl. Phys. 109, 064502 (2011).

    Article  Google Scholar 

  12. Houili, H., Tutiš, E., Lütjens, H., Bussac, M. & Zuppiroli, L. MOLED: Simulation of multilayer organic light emitting diodes. Comput. Phys. Commun. 156, 108–122 (2003).

    Article  CAS  Google Scholar 

  13. Coehoorn, R. & van Mensfoort, S. L. M. Effects of disorder on the current density and recombination profile in organic light-emitting diodes. Phys. Rev. B 80, 085302 (2009).

    Article  Google Scholar 

  14. Van Mensfoort, S. L. M. et al. Measuring the light emission profile in organic light-emitting diodes with nanometre spatial resolution. Nature Photon. 4, 329–335 (2010).

    Article  CAS  Google Scholar 

  15. Li, G. et al. Combinatorial study of exciplex formation at the interface between two wide band gap organic semiconductors. Appl. Phys. Lett. 88, 253505 (2006).

    Article  Google Scholar 

  16. Furno, M., Meerheim, R., Hofmann, S., Lüssem, B. & Leo, K. Efficiency and rate of spontaneous emission in organic electroluminescent devices. Phys. Rev. B 85, 115205 (2012).

    Article  Google Scholar 

  17. Van der Holst, J. J. M., van Oost, F. W. A., Coehoorn, R. & Bobbert, P. A. Monte Carlo study of charge transport in organic sandwich-type single-carrier devices: Effects of Coulomb interactions. Phys. Rev. B 83, 085206 (2011).

    Article  Google Scholar 

  18. Van Mensfoort, S. L. M., Shabro, V., de Vries, R. J., Janssen, R. A. J. & Coehoorn, R. Hole transport in the organic small-molecule material α-NPD: Evidence for the presence of correlated disorder. J. Appl. Phys. 107, 113710 (2010).

    Article  Google Scholar 

  19. Van Mensfoort, S. et al. Electron transport in the organic small-molecule material BAlq the role of correlated disorder and traps. Org. Elec. 11, 1408–1413 (2010).

    Article  CAS  Google Scholar 

  20. Mandoc, M. M., de Boer, B., Paasch, G. & Blom, P. W. M. Trap-limited electron transport in disordered semiconducting polymers. Phys. Rev. B 75, 193202 (2007).

    Article  Google Scholar 

  21. May, F., Baumeier, B., Lennartz, C. & Andrienko, D. Can lattice models predict the density of states of amorphous organic semiconductors? Phys. Rev. Lett. 109, 136401 (2011).

    Article  Google Scholar 

  22. Olthof, S. et al. Ultralow doping in organic semiconductors: Evidence of trap filling. Phys. Rev. Lett. 109, 176601 (2012).

    Article  Google Scholar 

  23. Miller, A. & Abrahams, E. Impurity conduction at low concentrations. Phys. Rev. 120, 745–755 (1960).

    Article  CAS  Google Scholar 

  24. Cottaar, J., Koster, L. J. A., Coehoorn, R. & Bobbert, P. A. Scaling theory for percolative charge transport in disordered molecular semiconductors. Phys. Rev. Lett. 107, 136601 (2011).

    Article  CAS  Google Scholar 

  25. Marcus, R. A. Electron transfer reactions in chemistry. Theory and experiment. Rev. Mod. Phys. 65, 599–610 (1993).

    Article  CAS  Google Scholar 

  26. 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).

    Article  Google Scholar 

  27. Steinbacher, F. S., Krause, R., Hunze, A. & Winnacker, A. Triplet exciton transfer mechanism between phosphorescent organic dye molecules. Phys. Stat. Sol. A 209, 340–346 (2012).

    Article  CAS  Google Scholar 

  28. Van der Holst, J. J. M., van Oost, F. W. A., Coehoorn, R. & Bobbert, P. A. Electron–hole recombination in disordered organic semiconductors: Validity of the Langevin formula. Phys. Rev. B 80, 235202 (2009).

    Article  Google Scholar 

  29. Kwiatkowski, J. J. et al. Simulating charge transport in tris(8-hydroxyquinoline) aluminium (Alq3). Phys. Chem. Chem. Phys. 10, 1852–1858 (2008).

    Article  CAS  Google Scholar 

  30. Rühle, V. et al. Microscopic simulations of charge transport in disordered organic semiconductors. J. Chem. Theor. Comput. 7, 3335–3345 (2011).

    Article  Google Scholar 

  31. Cottaar, J., Coehoorn, R. & Bobbert, P. A. Scaling theory for percolative charge transport in molecular semiconductors: Correlated versus uncorrelated energetic disorder. Phys. Rev. B 85, 245205 (2012).

    Article  Google Scholar 

  32. Cottaar, J., Coehoorn, R. & Bobbert, P. A. Field-induced detrapping in disordered organic semiconducting host–guest systems. Phys. Rev. B 82, 205203 (2010).

    Article  Google Scholar 

  33. Mladenovski, S., Reineke, S. & Neyts, K. Measurement and simulation of exciton decay times in organic light-emitting devices with different layer structures. Opt. Lett. 34, 1375–1377 (2009).

    Article  CAS  Google Scholar 

  34. Tang, K-C., Liu, K. L. & Chen, I-C. Rapid intersystem crossing in highly phosphorescent iridium complexes. Chem. Phys. Lett. 386, 437–441 (2004).

    Article  CAS  Google Scholar 

  35. Schwartz, G., Reineke, S., Rosenow, T., Walzer, K. & Leo, K. Triplet harvesting in hybrid white organic light-emitting diodes. Adv. Funct. Mater. 19, 1319–1333 (2009).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

This research was supported by the European Community (Program No. FP7-213708 (AEVIOM), M.S., M.F., B.L., K.L., P.L., R.C. and P.A.B.), the Dutch nanotechnology programmes NanoNed (J.J.M.v.d.H.) and NanoNextNL (M.M., H.v.E.), and the Dutch Polymer Institute (DPI), projects No. 518 (M.C.) and 680 (R.J.d.V.). The authors thank J. Cottaar, H. Nicolai, R. Nitsche, B. Ruhstaller, P. Blom and N. Greenham for the many discussions we had at the AEVIOM meetings and other occasions. The value of the hole mobility of α-NPD in Table 1 was established with the help of R. Nitsche. M. de Vries performed the measurements from which the parameter values for NET5 and Spiro-DPVBi in Table 1 were obtained. We acknowledge the contributions of F. W. A. van Oost to the simulation codes.

Author information

Authors and Affiliations

  1. Department of Applied Physics, Technische Universiteit Eindhoven, NL-5600 MB Eindhoven, PO Box 513, The Netherlands

    Murat Mesta, Marco Carvelli, Rein J. de Vries, Harm van Eersel, Jeroen J. M. van der Holst, Reinder Coehoorn & Peter A. Bobbert

  2. Philips Research Laboratories, High Tech Campus 4, NL-5656 AE Eindhoven, The Netherlands

    Marco Carvelli, Rein J. de Vries, Harm van Eersel & Reinder Coehoorn

  3. Dutch Polymer Institute, PO Box 902, NL-5600 AX Eindhoven, The Netherlands

    Marco Carvelli & Rein J. de Vries

  4. Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-Strasse 1, D-01062 Dresden, Germany

    Matthias Schober, Mauro Furno, Björn Lüssem & Karl Leo

  5. Philips Research Aachen, Weisshausstrasse 2, D-52066 Aachen, Germany

    Peter Loebl

Authors
  1. Murat Mesta
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Marco Carvelli
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Rein J. de Vries
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Harm van Eersel
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Jeroen J. M. van der Holst
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Matthias Schober
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Mauro Furno
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Björn Lüssem
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. Karl Leo
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. Peter Loebl
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. Reinder Coehoorn
    View author publications

    You can also search for this author in PubMed Google Scholar

  12. Peter A. Bobbert
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

M.M. and M.C. contributed equally to the work: M.M. performed the main Monte Carlo simulations and M.C. the main measurements on the OLED; R.J.d.V. determined the electron-transport parameters in Spiro-DPVBi and NET5; H.v.E. programmed the exciton diffusion software and prepared part of the figures; J.J.M.v.d.H. was involved in setting up the Monte Carlo simulations; M.S. and M.F. fabricated the OLED, provided its experimental optimization and characterization, and determined hole transport parameters, all supervised by B.L. and K.L.; P.L. was involved in the definition of the OLED stack, the UPS and optical measurements on the stack materials, and the fabrication of devices for the determination of electron transport parameters; R.C. supervised the whole project and contributed to the writing; P.A.B. supervised the simulation work and wrote the main part of the manuscript.

Corresponding author

Correspondence to Peter A. Bobbert.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 691 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Mesta, M., Carvelli, M., de Vries, R. et al. Molecular-scale simulation of electroluminescence in a multilayer white organic light-emitting diode. Nature Mater 12, 652–658 (2013). https://doi.org/10.1038/nmat3622

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat3622

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing