The internal electric field distribution in bilayer organic light emitting diodes

The internal electric field distribution in a bilayer 4,4'-bis[N-(1-napthyl)-N-phenylamino]-biphenyl/tris-(8-hydroxyquinoline) aluminium organic light emitting diode has been investigated experimentally using electroabsorption spectroscopy. The experimental results have been compared to those obtained from a drift-diffusion device simulation, further validating the model and highlighting the potential worth of such modelling. With the aid of the simulation, the electric field distribution can be explained in terms of charge carrier accumulation at the interface between the two organic layers, due to the HOMO and LUMO band offsets, and charge injection into the device, demonstrating the influence of contact materials on device behaviour. (C) 2002 Elsevier Science B.V. All rights reserved.