Enhancement of the lifetime in organic light-emitting devices fabricated utilizing wide-bandgap-impurity-doped emitting layers

Abstract

The degradation behaviors of the electrical and the optical properties of organic light-emitting devices (OLEDs) fabricated with an emitting layer (EML) doped with or without a wide-bandgap-impurity were investigated. The OLEDs with a wide-bandgap-doped Alq(3) EML were more stable than those with an undoped Alq(3) EML. The existence of the doped wide-bandgap-impurity in the EML decreased the trap-charge density in the EML, resulting in an increase in the number of electrons in the Alq(3) EML. That increases in the number of electron in the Alq(3) EML for the OLEDs with a wide-bandgap-impurity decreased the staying time of the holes in the Alq(3) EML, resulting in an enhanced lifetime for the OLEDs. These results indicate that OLEDs with a wide-bandgap-impurity-doped EML hold promise for potential applications in long-lifetime OLED displays. (c) 2007 Elsevier B.V. All rights reserved.