AVS 50th International Symposium
    Contacts to Organic Materials Topical Conference Monday Sessions
       Session OM-MoA

Paper OM-MoA8
Direct Observation of the Evolution of the Molecular Orbital Energy Levels of a Silole Derivative as a Function of Magnesium Deposition

Monday, November 3, 2003, 4:20 pm, Room 318/319

Session: Contacts to Molecules and Molecular Films (II)
Presenter: N.J. Watkins, Naval Research Laboratory
Authors: N.J. Watkins, Naval Research Laboratory
A.J. Makinen, Naval Research Laboratory
Y. Gao, University of Rochester
M. Uchida, Chisso Corporation, Japan
Z.H. Kafafi, Naval Research Laboratory
Correspondent: Click to Email
The electronic structure of the interface formed by Mg deposition onto 2,5-bis(6-(2,2-bipyridyl))-1,1-dimethyl-3,4-diphenyl silacyclopentadiene (PyPySPyPy) was investigated using ultraviolet photoemission, inverse photoemission, and X-ray photoemission spectroscopies. PyPySPyPy is of interest due to its high electron mobility. In addition, organic light-emitting diodes (OLEDs) using this silole derivative in the electron injection/transport layer exhibit very low operating voltages. Upon deposition of Mg onto PyPySPyPy a shift of the occupied molecular orbital energy level structure to higher binding energy, away from the Fermi level, was observed and accompanied by the appearance of two new levels within the energy gap of PyPySPyPy. These new levels have been assigned to a charge transfer complex between Mg and PyPySPyPy. At high Mg coverage, the shift in the lowest unoccupied molecular orbital can be correlated with the formation of "metallic-like" Mg clusters. The impact of these results on charge injection at the Mg metal contact in an OLED structure will be discussed.