Band bending of LiF/Alq3 interface in organic light-emitting diodes
Open Access
- 30 September 2003
- journal article
- research article
- Published by AIP Publishing in Applied Physics Letters
- Vol. 83 (14), 2949-2951
- https://doi.org/10.1063/1.1616977
Abstract
The insertion of LiF for an interlayer material between the Alcathode and tris-(8-hydroxyquinoline) aluminum ( Alq 3 ) in the organic light-emitting diodes(OLEDs) provides an improved device performance. The highly occupied molecular orbital (HOMO) level lowering in the Alq 3 layer induced by a low-coverage LiF deposition results in the reduction of electron injection barrier height. We investigated the electronic structure of the interface between the ultrathin LiF and the Alq 3 layer, using synchrotron x-ray photoelectron emission spectroscopy. The results revealed that the major origin of the HOMO level lowering is not the chemical bonding of dissociated fluorine in the Alq 3 layer but the band bending caused by charge redistribution driven by work function difference between LiF and Alq 3 layer.Keywords
This publication has 15 references indexed in Scilit:
- Chemical structure of Al/LiF/Alq interfaces in organic light-emitting diodesApplied Physics Letters, 2002
- Tris-(8-hydroxyquinoline)aluminum-based organic light-emitting devices with Al/CaF2 cathode: Performance enhancement and interface electronic structuresApplied Physics Letters, 2002
- Interface-limited injection in amorphous organic semiconductorsPhysical Review B, 2001
- Photoelectron spectroscopy study of the electronic structures of Al/MgF2/tris-(8-hydroxyquinoline) aluminum interfacesApplied Physics Letters, 2001
- Photoemission spectroscopy of LiF coated Al and Pt electrodesJournal of Applied Physics, 1998
- Electronic structure of 8-hydroxyquinoline aluminum/LiF/Al interface for organic electroluminescent device studied by ultraviolet photoelectron spectroscopyApplied Physics Letters, 1998
- Bright blue organic light-emitting diode with improved color purity using a LiF/Al cathodeJournal of Applied Physics, 1998
- Enhanced electron injection in organic electroluminescence devices using an Al/LiF electrodeApplied Physics Letters, 1997
- Confinement of charge carriers and molecular excitons within 5-nm-thick emitter layer in organic electroluminescent devices with a double heterostructureApplied Physics Letters, 1990
- Electroluminescence of doped organic thin filmsJournal of Applied Physics, 1989