HIGHLY EFFICIENT AND STABLE ORGANIC LIGHT-EMITTING-DIODES

Doped and undoped multilayer organic light-emitting diodes containing copper phthalocyanine as the hole-injection layer, aromatic diamines a s the hole-transport layers and (tris(8-hydroxy-quinoline)aluminum) as the electron-injection, electron-transport, and emitting layer were f abricated. The influence of the individual layer thicknesses and dopin g locations (electron-transport layer and/or hole-transport layer) on the current-voltage characteristics, luminous efficiency, and stabilit y was investigated. Optimization of these parameters led to highly eff icient(above 81m/W) and stable organic light-emitting diodes. (C) 1997 Published by Elsevier Science S.A.