Effect of the top electrode work function on the rectification ratio of light-emitting diodes (LEDs) based on poly(3-octylthiophene)

Frank Garten; J. Vrijmoeth; Albert R. Schlatmann; Richard E. Gill; Teun M. Klapwijk; Georges Hadziioannou

doi:10.1117/12.219561

15 September 1995 Effect of the top electrode work function on the rectification ratio of light-emitting diodes (LEDs) based on poly(3-octylthiophene)

Frank Garten, J. Vrijmoeth, Albert R. Schlatmann, Richard E. Gill, Teun M. Klapwijk, Georges Hadziioannou

Author Affiliations +

Proceedings Volume 2528, Optical and Photonic Applications of Electroactive and Conducting Polymers; (1995) https://doi.org/10.1117/12.219561
Event: SPIE's 1995 International Symposium on Optical Science, Engineering, and Instrumentation, 1995, San Diego, CA, United States

Abstract

Electroluminescence efficiency and current-voltage characteristics of conjugated polymer poly(3-octylthiophene) (P3OT) light emitting diodes (LEDs) are discussed in terms of the presently popular band model. Devices were studied in forward and reverse mode of operation, with different types of top contacts to show the dominance of the top electrode workfunction on device properties. Changing the workfunction of the top contact with only 0.9 eV (from Au to Al) results in a change in the preferred current direction, corresponding to a change in the rectification ratio of the diodes of effectively 6 orders of magnitude. When Au is used as a top electrode, no electroluminescence was observed, because the barrier for electron injection is too high. The observation of light emission in the reverse mode of operation for ITO/P3OT/Al is a result of direct carrier tunneling into the transport bands at high electric fields.

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Frank Garten, J. Vrijmoeth, Albert R. Schlatmann, Richard E. Gill, Teun M. Klapwijk, and Georges Hadziioannou "Effect of the top electrode work function on the rectification ratio of light-emitting diodes (LEDs) based on poly(3-octylthiophene)", Proc. SPIE 2528, Optical and Photonic Applications of Electroactive and Conducting Polymers, (15 September 1995); https://doi.org/10.1117/12.219561

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