6533b851fe1ef96bd12a9692
RESEARCH PRODUCT
Effect of driving method on the degradation of organic light emitting diodes
A. Di CristofaloF. ButtittaClaudio CaliP. Cusumanosubject
Materials sciencebusiness.industryMechanical EngineeringJoule effectMetals and AlloysCondensed Matter PhysicsCathodeElectronic Optical and Magnetic Materialslaw.inventionAnodeMechanics of MaterialslawElectric fieldMaterials ChemistryOLEDOptoelectronicsJoule heatingbusinessLight-emitting diodeVoltagedescription
Abstract Lifetime testing results are reported for organic light emitting diodes (OLEDs) having the structure ITO (anode)/ N , N ′-diphenyl- N , N ′-bis(3-methylphenyl)-1,1′-diphenyl-4,4′-diamine (TPD)/tris-(8-hydroxyquinoline)aluminum (AlQ)/Al (cathode) and operated using dc and pulsed waveforms for comparison. In ambient atmosphere non-encapsulated devices show a lifetime of about 70 h in pulsed operation at an initial luminance of 500 cd/m 2 , almost four times longer than in dc operation. A fast initial decay of luminance is observed for dc operation. It is most probably due to a combination of Joule heating and mobile ionic impurities migration within the OLED structure under the continuous forward electric field. We study also the transient electroluminescence (EL) and report the observation of a short duration spike in the leading edge of the EL response. Its origin is attributed to the temporal shift of the recombination zone in the AlQ layer from the bulk to the interface with TPD subsequent the application of a voltage step.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2003-10-09 | Synthetic Metals |