Enhanced performance in organic light-emitting diodes with copolymers containing both tris(8-hydroxyquinoline) aluminum and 8-hydroxyquinoline lithium groups

Abstract

We synthesized novel copolymers containing both tris(8-hydroxyquinoline) aluminum (Alq3) and 8-hydro-xyquinoline lithium (Liq) groups as emitting layers for use in conventional two-layer organic light-emitting diodes. The network structure and thermal stability of these materials is described. The optical and electroluminescent properties of the copolymers were also studied. The performance optimization of the devices with the copolymers through the variation of the ratio of Alq3 to Liq is described. A mechanism responsible for the improved electron injection is put forward. © 2006 Wiley Periodicals, Inc.