Applied Physics Letters · 2007 · 262 citations · 17 references
EngineeringMaterials EngineeringMaterials ScienceElectronic MaterialsOptoelectronicsSemiconductor MaterialsLight-emitting DiodesLuminescent MaterialsOptoelectronic DevicesOptoelectronic MaterialsOrganic SemiconductorsWide Band Gap SemiconductorsDirect InjectionElectron Work FunctionIndium Tin Oxide Thin FilmsLight-emitting DevicesMolecular Orbital AnalysisOrganic ElectronicsOrganic Light-emitting DiodesWork Function
The authors report on highly efficient organic light emitting diodes (OLEDs) consisting of only two organic layers. The key to the simplification is the direct injection of holes into the wide band gap hole transport material 4,4′,4″-tris(N-carbazolyl)-triphenyl amine (highest occupied molecular orbital is 5.9eV) through an indium tin oxide/tungsten oxide (WO3) anode. Kelvin probe analysis has revealed an extremely high work function of 6.4eV for WO3. The efficiencies of the simplified OLEDs exceed 40lm∕W and 45cd∕A at a brightness of 100cd∕m2, unsurpassed by other comparably simple OLED devices. Therefore, our OLED architecture demonstrates highly efficient, yet easy to fabricate devices.
17