Light-emission in reverse bias operation from poly(3- octylthiophene)-based light-emitting-diodes

F. Garten, A. R. Schlatmann, R. E. Gill, J. Vrijmoeth, T. M. Klapwijk, G. Hadziioannou

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    We report light emission from light emitting diodes with poly(3‐octylthiophene) (P3OT) as the active layer in both forward and reverse bias operation. The onset of electroluminescence (EL) of ITO/P3OT/Al devices occurs at current densities of 6.25×10−4 A/cm2 in both modes of operation; both cases show identical EL spectra. For a P3OT thickness of 100 nm the onset of electroluminescence and current occurs at 3 V in the forward bias mode, and at about 18 V in the reverse mode of operation, at which a completely different voltage dependence of the current is observed. In the reverse mode of operation, the data suggest that carrier injection is a tunneling process through a triangular barrier of 0.4 eV at the metal–polymer interface. In the forward bias a Schottky‐like behavior is seen.
    Original languageEnglish
    Pages (from-to)2540-2542
    Number of pages3
    JournalApplied Physics Letters
    Issue number19
    Publication statusPublished - 8-May-1995

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