Doped organic electroluminescent devices with improved stability

Abstract

Remarkable improvement in stability has been demonstrated in an organic electroluminescent (EL) device using a doped emitter consisting of 8-hydroxyquinoline aluminum (Alq) as the host and N,N-dimethylquinacridone (DMQA) as the emissive dopant. A luminance half-life on the order of about 7500 h has been achieved in the DMQA/Alq EL device, operating under a constant current of 20 ${\mathrm{mA/cm}}^2$ and starting at a high luminance of 1400 ${\mathrm{cd/m}}^2.$ The improved stability was attributed to the elimination of intermolecular hydrogen bonding between the dopant molecules.