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Extremely efficient flexible organic light-emitting diodes with modified graphene anode

Nature Photonics volume 6, pages 105–110 (2012)Cite this article

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Abstract

Although graphene films have a strong potential to replace indium tin oxide anodes in organic light-emitting diodes (OLEDs), to date, the luminous efficiency of OLEDs with graphene anodes has been limited by a lack of efficient methods to improve the low work function and reduce the sheet resistance of graphene films to the levels required for electrodes1,2,3,4. Here, we fabricate flexible OLEDs by modifying the graphene anode to have a high work function and low sheet resistance, and thus achieve extremely high luminous efficiencies (37.2 lm W–1 in fluorescent OLEDs, 102.7 lm W–1 in phosphorescent OLEDs), which are significantly higher than those of optimized devices with an indium tin oxide anode (24.1 lm W–1 in fluorescent OLEDs, 85.6 lm W–1 in phosphorescent OLEDs). We also fabricate flexible white OLED lighting devices using the graphene anode. These results demonstrate the great potential of graphene anodes for use in a wide variety of high-performance flexible organic optoelectronics.

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Figure 1: Schematic illustrations of hole injection from graphene, device structure and fabrication steps for flexible OLEDs.
Figure 2: Performance of green OLEDs with graphene, carbon nanotube and ITO anodes.
Figure 3: Device structure and performance of white OLEDs with a graphene anode, and the flexible OLED lighting device.
Figure 4: DI SCLC transient current and hole-injection efficiency of graphene anodes and ITO anode.

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Acknowledgements

This research was supported by the Basic Research Program and Global Frontier Research Center for Advanced Soft Electronics through the National Research Foundation of Korea (NRF), funded by the Ministry of Education, Science and Technology (nos. 2009-0067533, 2009-0075025, 2011-0006268 and 2009-0090177). This research was also supported by the Converging Research Center Program through the Ministry of Education, Science and Technology (no. 2010K001431).

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Authors and Affiliations

  1. Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Gyungbuk, Republic of Korea

    Tae-Hee Han, Mi-Ri Choi, Seong-Hoon Woo & Tae-Woo Lee

  2. SKKU Advanced Institute of Nanotechnology (SAINT), Center for Human Interface Nano Technology (HINT) and School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, 440-746, Gyeonggi-do, Republic of Korea

    Youngbin Lee, Sang-Hoon Bae & Jong-Hyun Ahn

  3. Department of Chemistry, Seoul National University, Seoul, 151-747, Republic of Korea

    Byung Hee Hong

Authors
  1. Tae-Hee Han
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Contributions

T.-H.H. designed and conducted most of the experiments, analysed the data and prepared the manuscript. Y.L. and S.-H.B. conducted experiments regarding graphene growth, patterning of graphene anodes and characterization. S.-H.W. and M.-R.C. helped with the OLED fabrication experiments. B.H.H. interpreted data and suggested improvements to the manuscript. J.-H.A. designed the graphene experiments, analysed data and prepared the manuscript. T.-W.L. initiated the study, designed all the experiments, analysed the data and prepared the manuscript. All authors discussed the results and contributed to the paper.

Corresponding authors

Correspondence to Jong-Hyun Ahn or Tae-Woo Lee.

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The authors declare no competing financial interests.

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Han, TH., Lee, Y., Choi, MR. et al. Extremely efficient flexible organic light-emitting diodes with modified graphene anode. Nature Photon 6, 105–110 (2012). https://doi.org/10.1038/nphoton.2011.318

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