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Molecular‐Level Offset at the PTCDA/Alq 3 Heterojunction
Author(s) -
Rajagopal Aparna,
Kahn Antoine
Publication year - 1998
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/(sici)1521-4095(199801)10:2<140::aid-adma140>3.0.co;2-1
Subject(s) - heterojunction , materials science , homo/lumo , optoelectronics , oled , electroluminescence , luminescence , diode , organic semiconductor , electron , semiconductor , photoemission spectroscopy , x ray photoelectron spectroscopy , layer (electronics) , nanotechnology , molecule , chemistry , physics , organic chemistry , quantum mechanics , nuclear magnetic resonance
A theoretical understanding of molecular interfaces , such as in organic light‐emitting diodes (OLEDs), comparable to that of conventional covalent semiconductor heterojunctions does not exist at the moment. A step in this direction is made here, with the determination via photoemission spectroscopy of HOMO and LUMO levels across a PTCDA/Alq 3 heterojunction. It is shown that the relative position of the LUMOs is inadequate to confine electrons in the emissive layer (Alq 3 ), which explains in part the low luminescence efficiency of PTCDA/Alq 3 OLED devices.