AVS 46th International Symposium
    Organic Electronic Materials Topical Conference Monday Sessions
       Session OE+EM+FP-MoM

Paper OE+EM+FP-MoM4
Unoccupied Molecular Orbitals in Organic Electroluminescent Materials Studied by Femtosecond Harmonic Photoemission

Monday, October 25, 1999, 9:20 am, Room 616/617

Session: Organic Devices
Presenter: H.S. Karlsson, Royal Institute of Technology, Sweden
Authors: H.S. Karlsson, Royal Institute of Technology, Sweden
K. Read, University of Michigan
R. Haight, IBM T.J. Watson Research Center
Correspondent: Click to Email
We have studied the lowest unoccupied molecular orbital (LUMO) in three organic electroluminescent materials using pump-probe harmonic photoemission based on a femtosecond laser system. The energy gap between the LUMO and the highest occupied molecular orbital (HOMO) in thin films of the blue-light-emitting molecules bis(2-methyl-8-quinolinolato)(para-phenyl-phenolato)aluminum (BAlq) and 1,4-bis(2,2-diphenylvinyl)biphenyl (DPVBi) was established and compared with the green-light-emitting molecule tris(8-hydroxyquinoline)aluminum (Alq). We have also studied the LUMO decay characteristics for the three materials and relate the differences in decay times to the morphology of the evaporated thin films. The effect on the electronic structure of the organics induced by deposition of metallic overlayers will also be shown and discussed.