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High-efficiency fluorescent organic light-emitting devices using a phosphorescent sensitizer

Nature volume 403, pages 750–753 (2000)Cite this article

Abstract

To obtain the maximum luminous efficiency from an organic material, it is necessary to harness both the spin-symmetric and anti-symmetric molecular excitations (bound electron–hole pairs, or excitons) that result from electrical pumping. This is possible if the material is phosphorescent, and high efficiencies have been observed in phosphorescent1,2 organic light-emitting devices3. However, phosphorescence in organic molecules is rare at room temperature. The alternative radiative process of fluorescence is more common, but it is approximately 75% less efficient, due to the requirement of spin-symmetry conservation4. Here, we demonstrate that this deficiency can be overcome by using a phosphorescent sensitizer to excite a fluorescent dye. The mechanism for energetic coupling between phosphorescent and fluorescent molecular species is a long-range, non-radiative energy transfer: the internal efficiency of fluorescence can be as high as 100%. As an example, we use this approach to nearly quadruple the efficiency of a fluorescent red organic light-emitting device.

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Figure 1: Proposed energy transfer mechanisms in the sensitized system.
Figure 2: The external quantum efficiencies of DCM2 emission in the three devices.
Figure 3: The spectra of the three electroluminescent devices fabricated in this work.
Figure 4: The transient response of the DCM2 and Ir(ppy)3 spectral components in the CBP/10% Ir(ppy)3/1% DCM2 device.

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Acknowledgements

This work was supported by Universal Display Corporation, the Defense Advanced Research Projects Agency, the Air Force Office of Scientific Research and the National Science Foundation.

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Authors and Affiliations

  1. Department of Electrical Engineering and the Princeton Materials Institute, Center for Photonics and Optoelectronic Materials (POEM), Princeton University, Princeton, 08544, New Jersey , USA

    M. A. Baldo & S. R. Forrest

  2. Department of Chemistry, University of Southern California, Los Angeles, 90089, California, USA

    M. E. Thompson

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  1. M. A. Baldo
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  2. M. E. Thompson
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  3. S. R. Forrest
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Correspondence to S. R. Forrest.

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Baldo, M., Thompson, M. & Forrest, S. High-efficiency fluorescent organic light-emitting devices using a phosphorescent sensitizer. Nature 403, 750–753 (2000). https://doi.org/10.1038/35001541

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