AVS 56th International Symposium & Exhibition
    Advanced Surface Engineering Tuesday Sessions
       Session SE-TuP

Paper SE-TuP4
Light Out-Coupling Characteristics Based-on the Interfacial Electronic Structure of MoOx-doped Fullerene, a Potential Hole Ohmic-Contact Layer for Organic Semiconductor

Tuesday, November 10, 2009, 6:00 pm, Room Hall 3

Session: Advanced Surface Engineering Poster Session
Presenter: J.T. Lim, Sungkyunkwan University, Korea
Authors: J.T. Lim, Sungkyunkwan University, Korea
J.W. Kwon, Sungkyunkwan University, Korea
G.Y. Yeom, Sungkyunkwan University, Korea
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Recently, the interest on the ohmic contact between the metal-organic interfaces has been actively increasing to inject charge carriers between electrodes and an adjoining organic layers more efficiently. Among those contact, the hole-injecting properties without a barrier height between anode and a hole-injecting layer are very important for driving the devices to a high brightness and a high luminous efficiency in organic semiconductors, such as the organic light-emitting diodes, organic solar cells, and organic thin film transistors. Here, we reported on the new ohmic-hole contact system of MoOx-doped fullerene. The phosphorescent organic light-emitting diode with fullerene doped with 10% MoOx showed the maximum brightness of 86500 cd/m2 and the power efficiency of 15.6 lm/W at a luminance of 100 cd/m2. The improvement of the light out-coupling property by inserting the MoOx–doped fullerene layer between anode and a hole-transporting layer is due to the formation of an ohmic contact without the barrier height in a hole injection (ΦBh) as well as the raising of the band banding by pinning Fermi levels in the interfaces. The mechanism for the ohmic hole-injecting characteristic from anode to MoOx–doped fullerene was proved from an ultraviolet photoemission spectroscopy (UPS) sepctra. In UPS spectra, the highest occupied molecular orbital (HOMO) level of the interface formed between two materials nearly approaches to Fermi level of anode.