A CHEMICAL FAILURE-MECHANISM FOR ALUMINUM(III) 8-HYDROXYQUINOLINE LIGHT-EMITTING DEVICES

A plausible degradation mechanism of aluminum(III) 8-hydroxyquinoline (Alq(3))-based devices is presented. This is initiated by traces of mo isture that facilitate a ligand exchange with the oxyquinoline moiety of Alq(3), followed by a condensation polymerization of the freed 8-hy droxyquinoline (8-Hq) to produce a deep brown, nonemissive polymeric m aterial and water (which can in turn free more 8-Hq). The polymer was found to be an efficient photoluminescence and electroluminescence que ncher due to the introduction of nonemissive midgap states within the Alq(3) HOMO/LUMO levels.