Efficiency Enhancement Mechanism of Organic Light-Emitting Devices with an Alq₃ Emitting Layer Containing a DPVBi Wide Bandgap Doping Agent

Abstract

The efficiency of the organic light-emitting devices (OLEDs) with a tris-(8-hydroxyquinoline) aluminum (Alq₃) emitting layer (EML) containing a 4,4-bis(2,2diphenyl vinyl)-1,1-biphenyl (DPVBi) doping agent was significantly enhanced in comparison to that with an Alq₃ EML without a DPVBi doping agent. The enhancement of the injection efficiency of the OLEDs with an EML doped with a wide-bandgap doping agent was attributed to a decrease in the trap charge density existing in the EML resulting from the existence of the DPVBi doping agent. The luminescence mechanism of the OLEDs fabricated utilizing an Alq₃ EML containing a DPVBi wide-bandgap doping agent is described on the basis of the experimental results.

Keywords:

• luminescence mechanism
• organic light-emitting devices
• wide-bandgap doping agent

PACS numbers:

• 78. 60. Fi And 78. 66. Qn