A Chemical Failure Mechanism for Aluminum(III) 8-Hydroxyquinoline Light-Emitting Devices

Abstract

A plausible degradation mechanism of aluminum(III) 8-hydroxyquinoline (Alq3)-based devices is presented. This is initiated by traces of moisture that facilitate a ligand exchange with the oxyquinoline moiety of Alq3, followed by a condensation polymerization of the freed 8-hydroxyquinoline (8-Hq) to produce a deep brown, nonemissive polymeric material and water (which can in turn free more 8-Hq). The polymer was found to be an efficient photoluminescence and electroluminescence quencher due to the introduction of nonemissive midgap states within the Alq3 HOMO/LUMO levels.