Applied Physics Letters · 2009 · 682 citations · 24 references
Natural SciencesChemistryMaterials ScienceElectronic MaterialsSemiconductor MaterialsThin FilmsMolecular Orbital TheoryOrganic Electronic MaterialsOrganic SemiconductorsOxide SemiconductorsSemiconductor InterfacesThin Film Electrical PropertiesConduction BandElectron AffinityElectronic Structure AnalysisInverse Photoelectron SpectroscopyIonization EnergyOrganic Thin FilmsOxide Electronic StructureUltraviolet Photoelectron Spectroscopy
The electronic structures of vacuum-deposited molybdenum trioxide (MoO3) and of a typical MoO3/hole transport material (HTM) interface are determined via ultraviolet and inverse photoelectron spectroscopy. Electron affinity and ionization energy of MoO3 are found to be 6.7 and 9.68 eV, more than 4 eV larger than generally assumed, leading to a revised interpretation of the role of MoO3 in hole injection in organic devices. The MoO3 films are strongly n-type. The electronic structure of the oxide/HTM interface shows that hole injection proceeds via electron extraction from the HTM highest occupied molecular orbital through the low-lying conduction band of MoO3.
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