By blending poly(ethylene glycol) (PEG) into an electroluminescence (EL) polymer, significantly enhanced EL efficiency in a polymer light–emitting diode (PLED) with aluminum electrode was achieved. An orange-color-emitting PLED with 10 wt% PEG blending achieved device efficiencies exceeding 2.6 cd/A for a wide range of bias voltage, which is more than two orders of magnitude higher than that for a similar PLED without the PEG blending. A similar enhancement was observed by introducing PEG as an ultra-thin interfacial layer between the emissive polymer and the cathode. The enhancement was also observed for several different species of emissive polymers, and for blending with either PEG or poly(ethylene oxide) (PEO) with different molecular weights. The enhanced efficiency was a result of the reduction of electron injection barrier height at the cathode-polymer interface. It is believed that interfacial interaction that is specific to Al plays an important role in the enhancement mechanism.
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H. Burroughes, D. D. C. Bradley, A. R. Brown, R. N. Marks, K. Mackay, R. H. Friend, P. L. Burns, and A. B. Homes, Nature 347, 539(1990).
D. Braun and A. J. Heeger, Appl. Phys. Lett. 58, 1982 (1991).
L. S. Hung, C. W. Tang, and M. G. Mason, Appl. Phys. Lett. 70, 152 (1997).
J. Yoon, J.-J. Kim, T.-W. Lee, and O.-O. Park, Appl. Phys. Lett. 76, 2152 (2000).
T. M. Brown, R. H. Friend, I. S. Millard, D. J. Lacey, J. H. Burroughes, and F. Cacialli, Appl. Phys. Lett. 77, 3096 (2000).
X. Yang, Y. Mo, W. Yang, G. Yu, and Y. Cao, Appl. Phys. Lett. 79, 563 (2001).
Q. Xu, J. Ouyang, and Y. Yang, Appl. Phys. Lett. 83. 4695(2003).
Tae-Woo Lee, O Ok Park, Lee-Mi Do, Taehyoung Zyung, Taek Ahn and Hong-Ku Shim J. Appl. Phys. 90, 2128 (2001).
Y.Cao, G. Yu, and A. J. Heeger, Adv. Mater. 12, 917 (1998).
X. Y. Deng, W. M. Lau, K. Y. Wong, K. H. Low, H. F. Chow and Y. Cao, Appl. Phys. Letts. 84, 3522(2004).
P. Dannetun, M. Logdlund, M. Fahlman, M. Boman, S. Stafstrom, W. R. Salaneck, R. Lazzaroni, C. Fredriksson, J. L. Bredas, S. Graham, R. H. Friend, A. B. Holmes, R. Zamboni and C. Taliani, Synth. Met. 55, 212(1993).
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Deng, X.Y., Wong, K.Y. Efficient Polymeric Light-emitting Devices with Aluminum Cathode. MRS Online Proceedings Library 871, 642 (2005). https://doi.org/10.1557/PROC-871-I6.42