F. Papadimitrakopoulos et al., A CHEMICAL FAILURE-MECHANISM FOR ALUMINUM(III) 8-HYDROXYQUINOLINE LIGHT-EMITTING DEVICES, Chemistry of materials, 8(7), 1996, pp. 1363
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.