AVS 45th International Symposium
    Organic Electronic Materials Topical Conference Tuesday Sessions
       Session OE+BI+EM-TuA

Paper OE+BI+EM-TuA8
A Grazing Incidence X-ray Diffraction Study of the Organic-Organic Interface for PTCDA Films Grown on Self-assembled Monolayers of Thiols on Gold

Tuesday, November 3, 1998, 4:20 pm, Room 327

Session: Organic Thin Film Growth
Presenter: M.C. Gerstenberg, Princeton University
Authors: M.C. Gerstenberg, Princeton University
F. Schreiber, Max-Planck-Institut für Metallforschung, Germany
P. Fenter, Argonne National Laboratory
T.Y.B. Leung, Princeton University
S.R. Forrest, Princeton University
G. Scoles, Princeton University
Correspondent: Click to Email
We present results from a grazing incidence X-ray diffraction study of 3,4,9,10 perylenetetracarboxylic dianhydride (PTCDA) films deposited on self-assembled monolayers (SAMs) of either decanethiols or 1,6 hexanedithiols on Au(111). The aim is to study the effect of changes at the organic-organic interface on the in-plane ordering of PTCDA and the SAM. Changing the number of chemisorbed Sulphur (S)atoms in the layer between the PTCDA and the metallic substrate is of interest in view of the importance of the charge injecting properties of the organic-inorganic interface in organic semiconductor devices. PTCDA is one of the most thoroughly studied van der Waals epitaxial systems. It has previously been shown that under non-equilibrium growth conditions (high incident flux of PTCDA and low substrate temperature) PTCDA layers order parallel to the Au(111) substrate with a well-defined in-plane structure in registry with the underlying substrate. Under the same conditions our first measurements have indicated an unaltered PTCDA in-plane ordering on both thiol SAMs. However, the orientation of the PTCDA in-plane structure changes with respect to the Au surface in both cases. No change in the ordering of the thiols was observed as the PTCDA was deposited. The confined full coverage c(4x2) layer of decanethiols melts at higher temperatures than the unconfined SAM. With melting, the order of the SAM was lost and was not fully recovered upon cooling. However, no significant change was seen in either the out-of-plane or in-plane scattering of PTCDA.