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.

  • Article
  • Published:

Spin Rabi flopping in the photocurrent of a polymer light-emitting diode

Nature Materials volume 7, pages 723–728 (2008)Cite this article

Abstract

Electron spin is fundamental in electrical and optical properties of organic electronic devices. Despite recent interest in spin mixing and spin transport in organic semiconductors, the actual spin coherence times in these materials have remained elusive. Measurements of spin coherence provide impartial insight into spin relaxation mechanisms, which is significant in view of recent models of spin-dependent transport and recombination involving high levels of spin mixing. We demonstrate coherent manipulation of spins in an organic light-emitting diode (OLED), using nanosecond pulsed electrically detected electron spin resonance to drive singlet–triplet spin Rabi oscillations. By measuring the change in photovoltaic response due to spin-dependent recombination, we demonstrate spin control of electronic transport and thus directly observe spin coherence over 0.5 μs. This surprisingly slow spin dephasing underlines that spin mixing is not responsible for magnetoresistance in OLEDs. The long coherence times and the spin manipulation demonstrated are crucially important for expanding the impact of organic spintronics.

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

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

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

Figure 1: Schematic diagram of the important recombination and dissociation mechanisms for polaron pairs in organic semiconductors.
Figure 2: Response of the OLED photocurrent to a resonant microwave pulse.
Figure 3: Coherent spin control of a polymer OLED: Rabi flopping in the photocurrent for a number of different microwave field parameters.
Figure 4: Schematic diagram of the device structure used in the electrically detected pulsed-ESR experiment.

Similar content being viewed by others

References

  1. Cundiff, S. T. et al. Rabi flopping in semiconductors. Phys. Rev. Lett. 73, 1178–1181 (1994).

    Article  CAS  Google Scholar 

  2. Stievater, T. H. et al. Rabi oscillations of excitons in single quantum dots. Phys. Rev. Lett. 87, 133603 (2001).

    Article  CAS  Google Scholar 

  3. Zrenner, A. et al. Coherent properties of a two-level system based on a quantum-dot photodiode. Nature 418, 612–614 (2002).

    Article  CAS  Google Scholar 

  4. Hasché, T. et al. Coherent external and internal phonons in quasi-one-dimensional organic molecular crystals. Phys. Rev. Lett. 86, 4060–4063 (2001).

    Article  Google Scholar 

  5. Lanzani, G., Cerullo, G., Brabec, C. & Sariciftci, N. S. Time domain investigation of the intrachain vibrational dynamics of a prototypical light-emitting conjugated polymer. Phys. Rev. Lett. 90, 047402 (2003).

    Article  CAS  Google Scholar 

  6. Kennedy, S. P., Garro, N. & Phillips, R. T. Coherent control of optical emission from a conjugated polymer. Phys. Rev. Lett. 86, 4148–4151 (2001).

    Article  CAS  Google Scholar 

  7. Lidzey, D. G. et al. Strong exciton–photon coupling in an organic semiconductor microcavity. Nature 395, 53–55 (1998).

    Article  CAS  Google Scholar 

  8. Schouwink, P., Lupton, J. M., von Berlepsch, H., Dähne, L. & Mahrt, R. F. Nonequilibrium polariton dynamics in organic microcavities. Phys. Rev. B 66, 081203 (2002).

    Article  Google Scholar 

  9. Krinichnyi, V. I. 2 mm waveband electron paramagnetic resonance spectroscopy of conducting polymers. Synth. Met. 108, 173–222 (2000).

    Article  CAS  Google Scholar 

  10. Xiong, Z. H., Wu, D., Vardeny, Z. V. & Shi, J. Giant magnetoresistance in organic spin-valves. Nature 427, 821–824 (2004).

    Article  CAS  Google Scholar 

  11. Reufer, M. et al. Spin-conserving carrier recombination in conjugated polymers. Nature Mater. 4, 340–346 (2005).

    Article  CAS  Google Scholar 

  12. Francis, T. L., Mermer, Ö., Veeraraghavan, G. & Wohlgenannt, M. Large magnetoresistance at room temperature in semiconducting polymer sandwich devices. New J. Phys. 6, 185 (2004).

    Article  Google Scholar 

  13. Wilkinson, J., Davis, A. H., Bussman, K. & Long, J. P. Evidence for charge-carrier mediated magnetic-field modulation of electroluminescence in organic light-emitting diodes. Appl. Phys. Lett. 86, 111109 (2005).

    Article  Google Scholar 

  14. Shuai, Z., Beljonne, D., Silbey, R. J. & Brédas, J. L. Singlet and triplet exciton formation rates in conjugated polymer light-emitting diodes. Phys. Rev. Lett. 84, 131–134 (2000).

    Article  CAS  Google Scholar 

  15. Karabunarliev, S. & Bittner, E. R. Spin-dependent electron-hole capture kinetics in luminescent conjugated polymers. Phys. Rev. Lett. 90, 057402 (2003).

    Article  Google Scholar 

  16. Beljonne, D., Ye, A., Shuai, Z. & Brédas, J. Chain length dependence of singlet and triplet exciton formation rates in organic light-emitting diodes. Adv. Funct. Mater. 14, 684–692 (2004).

    Article  CAS  Google Scholar 

  17. Frankevich, E. L. On mechanisms of population of spin substates of polaron pairs. Chem. Phys. 297, 315–322 (2004).

    Article  CAS  Google Scholar 

  18. Segal, M. et al. Extrafluorescent electroluminescence in organic light-emitting devices. Nature Mater. 6, 374–378 (2007).

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  20. Wohlgenannt, M., Tandon, K., Mazumdar, S., Ramasesha, S. & Vardeny, Z. V. Formation cross-sections of singlet and triplet excitons in π-conjugated polymers. Nature 409, 494–497 (2001).

    Article  CAS  Google Scholar 

  21. Murata, K. et al. Photogenerated polarons in poly(paraphenylene vinylene). Chem. Phys. 227, 191–201 (1998).

    Article  CAS  Google Scholar 

  22. Murata, K., Shimoi, Y., Abe, S., Noguchi, T. & Ohnishi, T. Time resolved ESR measurements of photoinduced polarons in PPV. Synth. Met. 101, 353–354 (1999).

    Article  CAS  Google Scholar 

  23. Silva, G. B., Santos, L. F., Faria, R. M. & Graeff, C. F. O. EDMR of MEH-PPV LEDs. Physica B 308–310, 1078–1080 (2001).

    Article  Google Scholar 

  24. Castro, F. A. et al. Electrically detected magnetic resonance of organic and polymeric light emitting diodes. J. Non-Cryst. Solids 338–340, 622–625 (2004).

    Article  Google Scholar 

  25. Lee, M.-K., Segal, M., Soos, Z. G., Shinar, J. & Baldo, M. A. Yield of singlet excitons in organic light-emitting devices: A double modulation photoluminesence-detected magnetic resonance study. Phys. Rev. Lett. 94, 137403 (2005).

    Article  Google Scholar 

  26. Yang, C. G., Ehrenfreund, E. & Vardeny, Z. V. Polaron spin-lattice relaxation time in π-conjugated polymers from optically detected magnetic resonance. Phys. Rev. Lett. 99, 157401 (2007).

    Article  CAS  Google Scholar 

  27. De Ceuster, J., Goovaerts, E., Bouwen, A., Hummelen, J. C. & Dyakonov, V. High-frequency (95 GHz) electron paramagnetic resonance study of the photoinduced charge transfer in conjugated polymer-fullerene composites. Phys. Rev. B 64, 195206 (2001).

    Article  Google Scholar 

  28. Boehme, C. & Lips, K. Theory of time-domain measurement of spin-dependent recombination with pulsed electrically detected magnetic resonance. Phys. Rev. B 68, 245105 (2003).

    Article  Google Scholar 

  29. Stegner, A. R. et al. Electrical detection of coherent 31P spin quantum states. Nature Phys. 2, 835–838 (2006).

    Article  CAS  Google Scholar 

  30. Harneit, W. et al. Room temperature electrical detection of spin coherence in C60 . Phys. Rev. Lett. 98, 216601 (2007).

    Article  CAS  Google Scholar 

  31. Gunnarsson, O. Superconductivity in fullerides. Rev. Mod. Phys. 69, 575–606 (1997).

    Article  CAS  Google Scholar 

  32. Dediu, V., Murgia, M., Matacotta, F. C., Taliani, C. & Barbanera, S. Room temperature spin polarized injection in organic semiconductor. Solid State Commun. 122, 181–184 (2002).

    Article  CAS  Google Scholar 

  33. Hu, B. & Wu, Y. Tuning magnetoresistance between positive and negative values in organic semiconductors. Nature Mater. 6, 985–991 (2007).

    Article  CAS  Google Scholar 

  34. Lupton, J. M. & Boehme, C. Magnetoresistance in organic semiconductors. Nature Mater. 7, 598 (2008).

    Article  CAS  Google Scholar 

  35. Nguyen, T. D., Sheng, Y., Rybicki, J., Veeraraghavan, G. & Wohlgenannt, M. Magnetoresistance in π-conjugated organic sandwich devices with varying hyperfine and spin–orbit coupling strengths, and varying dopant concentrations.. J. Mater. Chem. 17, 1995–2001 (2007).

    Article  CAS  Google Scholar 

  36. Bergeson, J. D., Prigodin, V. N., Lincoln, D. M. & Epstein, A. J. Inversion of magnetoresistance in organic semiconductors. Phys. Rev. Lett. 100, 067201 (2008).

    Article  CAS  Google Scholar 

  37. Desai, P. et al. Magnetoresistance and efficiency measurements of Alq3-based OLEDs. Phys. Rev. B 75, 094423 (2007).

    Article  Google Scholar 

  38. Prigodin, V. N., Bergeson, J. D., Lincoln, D. M. & Epstein, A. J. Anomalous room temperature magnetoresistance in organic semiconductors. Synth. Met. 156, 757–761 (2006).

    Article  CAS  Google Scholar 

  39. Kalinowski, J., Cocchi, M., Virgili, D., Di Marco, P. & Fattori, V. Magnetic field effects on emission and current in Alq3-based electroluminescent diodes. Chem. Phys. Lett. 380, 710–715 (2003).

    Article  CAS  Google Scholar 

  40. Bobbert, P. A., Nguyen, T. D., van Oost, F. W. A., Koopmans, B. & Wohlgenannt, M. Bipolaron mechanism for organic magnetoresistance. Phys. Rev. Lett. 99, 216801 (2007).

    Article  CAS  Google Scholar 

  41. Jiang, J. S., Pearson, J. E. & Bader, S. D. Absence of spin transport in the organic semiconductor Alq3 . Phys. Rev. B 77, 035303 (2008).

    Article  Google Scholar 

  42. Salis, G., Alvarado, S. F., Tschudy, M., Brunschwiler, T. & Allenspach, R. Hysteretic electroluminescence in organic light-emitting diodes for spin injection. Phys. Rev. B 70, 085203 (2004).

    Article  Google Scholar 

  43. Ohno, Y. et al. Electrical spin injection in a ferromagnetic semiconductor heterostructure. Nature 402, 790–792 (1999).

    Article  CAS  Google Scholar 

  44. Fiederling, R. et al. Injection and detection of a spin-polarized current in a light-emitting diode. Nature 402, 787–790 (1999).

    Article  Google Scholar 

  45. Motsnyi, V. F. et al. Optical investigation of electrical spin injection into semiconductors. Phys. Rev. B 68, 245319 (2003).

    Article  Google Scholar 

  46. Tombros, N., Jozsa, C., Popinciuc, M., Jonkman, H. T. & van Wees, B. J. Electronic spin transport and spin precession in single graphene layers at room temperature. Nature 448, 571–574 (2007).

    Article  CAS  Google Scholar 

  47. Wilson, J. S. et al. Spin-dependent exciton formation in π-conjugated compounds. Nature 413, 828–831 (2001).

    Article  CAS  Google Scholar 

  48. Arkhipov, V. I. & Bässler, H. Exciton dissociation and charge photogeneration in pristine and doped conjugated polymers. Phys. Status Solidi A 201, 1152–1187 (2004).

    Article  CAS  Google Scholar 

  49. Dyakonov, V., Rösler, G., Schwoerer, M. & Frankevich, E. L. Evidence for triplet interchain polaron pairs and their transformations in polyphenylenevinylene. Phys. Rev. B 56, 3852–3862 (1997).

    Article  CAS  Google Scholar 

  50. Schweiger, A. & Jeschke, G. Principles of Pulse Electron Paramagnetic Resonance (Oxford Univ. Press, Oxford, 2001).

    Google Scholar 

  51. Boroumand, F. A., Fry, P. W. & Lidzey, D. G. Nanoscale conjugated-polymer light-emitting diodes. Nano Lett. 5, 67–71 (2005).

    Article  CAS  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Department of Physics, University of Utah, Salt Lake City, Utah 84112, USA

    D. R. McCamey, H. A. Seipel, S.-Y. Paik, M. J. Walter, N. J. Borys, J. M. Lupton & C. Boehme

Authors
  1. D. R. McCamey
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. H. A. Seipel
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. S.-Y. Paik
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. M. J. Walter
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. N. J. Borys
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. J. M. Lupton
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. C. Boehme
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding authors

Correspondence to J. M. Lupton or C. Boehme.

Supplementary information

Supplementary Information

Supplementary Information, Figures S1–S3 and Table S1 (PDF 167 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

McCamey, D., Seipel, H., Paik, SY. et al. Spin Rabi flopping in the photocurrent of a polymer light-emitting diode. Nature Mater 7, 723–728 (2008). https://doi.org/10.1038/nmat2252

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat2252

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