Improved band alignment for hole injection by an interfacial layer in organic light emitting devices

Citation
L. Chkoda et al., Improved band alignment for hole injection by an interfacial layer in organic light emitting devices, APPL PHYS L, 77(8), 2000, pp. 1093-1095
Citations number
17
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
APPLIED PHYSICS LETTERS
ISSN journal
0003-6951 → ACNP
Volume
77
Issue
8
Year of publication
2000
Pages
1093 - 1095
Database
ISI
SICI code
0003-6951(20000821)77:8<1093:IBAFHI>2.0.ZU;2-W
Abstract
We demonstrate that a thin organic interfacial layer of 3,4,9,10 perylenete tracarboxylic dianhydride (PTCDA) can be utilized to improve the band align ment of N,N'-di-(3-methylphenyl)N,N'diphenyl-4,4'diaminobiphenyl (TPD) film s on [indium-tin-oxide (ITO)] (InSnO) substrates in, e.g., organic electrol uminescent devices. A photoemission study of the highest occupied molecular orbital (HOMO) and vacuum level position as a function of the organic over layer thickness reveals that due to chemisorptive bonding a thin PTCDA inte rlayer results in a reduced barrier between the Fermi level of ITO and the HOMO of TPD. Furthermore we detect a new molecular state 0.6 eV below the F ermi level at the PTCDA/ITO interface. Both effects are expected to improve the hole injection from the ITO anode into the TPD hole transport layer, e .g., in organic light emitting devices. (C) 2000 American Institute of Phys ics. [S0003-6951(00)05134-2].