Japanese Journal of Applied Physics · 2002 · 14 citations · 1 references
EngineeringMaterials EngineeringMaterials ScienceElectronic MaterialsOptical MaterialsSemiconductor MaterialsLight-emitting DiodesLighting MaterialsOrganic Electronic MaterialsOrganic SemiconductorsSemiconductor Device MaterialsSurface DegradationCarrier Transport In Organic SemiconductorsConstant Current BiasingImpuritiesLight-emitting DevicesOrganic ElectronicsOrganic Light-emitting DiodesOrganic Light-emitting MaterialsVoltage
Voltage increases of organic mono layered devices under constant-current operation were investigated in order to clarify the origin of the degradation of organic light emitting devices (OLED). The rate of voltage increase for tris(8-hydroxyquinoline)aluminum (Alq3), which is the most popular material for the electron transport layer, was the largest, whereas those for hole transporting materials (4,4',4''-tris(3-methylphenyl-phenylamino)-triphenyl-amine (MTDATA), 4,4'-bis[N-(1-naphthyl)-N-phenylamino] biphenyl (NPB), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD)) were small. The origin of the recoverable voltage change of the Alq3 layer was attributed to the electronic characteristic change of the Alq3 layer, that is, the ionic impurities or the orientation of Alq3 molecules.
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