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

Paper OE-MoP3
Investigation of the Growth Mode of Phenyldiamine (NPB) on Indium Tin Oxide

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

Session: Organic Electronic Materials Poster Session
Presenter: F.M. Avendano, University of Rochester
Authors: F.M. Avendano, University of Rochester
E.W. Forsythe, University of Rochester
Y. Gao, University of Rochester
C.W. Tang, Eastman Kodak Company
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Since the first report on Organic Light Emitting Devices (OLED)@footnote 1@ there has been much interest for their potential applications as flat panel displays. In these devices charge carriers are injected into the organic layers across the interfaces and the electrode/organic interface characteristics have a strong effect on the device efficiency. Among these characteristics, the morphology of the anode(Indium Tin Oxide) strongly affects the device stability@footnote 2@ as revealed by the presence of microshorts in I-V curves. We study the growth mode of N,N-bis-(1-naphthyl)-N,N-diphenyl-1,1-biphenyl-4,4-diamine (NPB) on Indium Tin Oxide (ITO)/Glass substrates using Atomic Force Microscopy (AFM) and Lateral Force Microscopy (LFM). The addition of LFM to AFM allows us to clearly distinguish the features due to NPB or ITO. The study was performed as a function of the ITO morphology and NPB thickness. In order to modify the ITO surface morphology a series of processing steps were applied reducing the roughness more than three times as compared to the as received ITO. Next, NPB was deposited with thickness of 5, 15, 30 and 150Å onto the flat and as received ITO. At 5Å of NPB on the flat ITO, AFM/LFM pictures reveal the formation of NPB islands. These islands start to coalesce at a thickness of 15Å. At 30Å of NPB on flat ITO the film exhibits some pinholes which are no longer present at 150Å of NPB on flat ITO. The NPB films grown onto as received ITO show ITO features at the thickness of 5, 15,and 30 Å of NPB and the roughness of the NPB film is an order of magnitude bigger as compared to the NPB grown onto flat ITO. These ITO features present in the NPB film grown onto as received ITO may have detrimental effects on device performance as a consequence of microshorts. @FootnoteText@ @footnote 1@C. W. Tang and S. A. Van Slyke, Appl. Phys. Lett. 51, 913 (1987) @footnote 2@F. M. Avendano, E. W. Forsythe and Yongli Gao. The American Physical Society, March 1998.