AVS 45th International Symposium
    Organic Electronic Materials Topical Conference Monday Sessions
       Session OE-MoP

Paper OE-MoP2
Ultraviolet and X-ray Photoemission Spectroscopy Characterization of Base and Acid Treated Indium Tin Oxide for Organic Device Applications

Monday, November 2, 1998, 5:30 pm, Room Hall A

Session: Organic Electronic Materials Poster Session
Presenter: F.A. Nüesch, University of Rochester
Authors: F.A. Nüesch, University of Rochester
E.W. Forsythe, University of Rochester
Y. Gao, University of Rochester
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Because of its transparency and high conductivity, indium tin oxide (ITO) electrodes are ideal for optoelectronic device applications. Its ability to inject charges into organic solids, however, depends strongly on the interface properties. The effective ITO workfunction can be modified by a surface treatment such as plasma cleaning and chemical treatments. Here, we report the ultraviolet and X-ray photoemission spectroscopy (UPS, XPS) of chemically modified ITO using acids and bases. The UPS results confirm the presence of a dipole layer at the base treated ITO surface, with a vacuum level decrease of more than 1 eV. Current-voltage characteristics of tris-(8-hydroxyqinoline) aluminum (Alq) films sandwiched between the treated oxide electrode and a metallic counter electrode are in agreement with the workfunction shifts obtained by the UPS measurements. From XPS results, we will report the surface composition of the ITO films. In addition to base treatments, we will report UPS and XPS results for acid treated ITO and correlate these results with device transport measurements. The construction of thin dipole layers on the ITO substrate is a promising technique to modify the effective work function of ITO and improve the overall organic LED performance.