The efficiency of the organic light-emitting devices (OLEDs) with a tris-(8-hydroxyquinoline) aluminum (Alq(3)) 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 Alq(3) 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 Alq(3) EML containing a DPVBi wide-bandgap doping agent is described on the basis of the experimental results.