Ultraviolet photoelectron spectroscopy on new heterocyclic materials for multilayer organic light emitting diodes

Electronic band structure of three heterocyclic model compounds: 5,12-dihyd ro-quinoxalino-2,3-b-phenazine; 7,18-dihydro-5,7,11,16,18,20,22-octa-aza-no nacene; and 1,3,5-Tris[(3-phenyl-6-tri-fluoro-methyl)-quinoxaline-2-yl]benz ene was studied by ultraviolet photoelectron spectroscopy. We also determin ed their ionisation potential, between 5.3 and 6.0 eV, suggesting that thes e materials can efficiently act as electron transporting layer in organic l ight emitting devices (OLEDs). (C) 2001 Elsevier Science B.V. All rights re served.