Active matrix organic-light-emitting-diode (AM OLED) panels, driven by organic thin-film transistors (OTFT), have been successfully fabricated on a flexible plastic substrate. The pixel circuit consists of two bottom-contact pentacene OTFTs working as switching and driving transistors. The panel has 16 × 16 pixels, each of which have an OLED using a phosphorescent material with an emission efficiency of 30 cd/A. A tantalum oxide (Ta 2 O 5 ) film with a dielectric constant of 24, prepared by the anodization of Tantalum (Ta), was used as the gate insulator of the OTFTs. The passivation layer on the OTFTs was formed by a layer of silicon dioxide (SiO 2 ) and two layers of polyvinyl alcohol. Using OTFTs with a Ta 2 O 5 gate insulator, the authors have realized a flexible active matrix OLED panel driven with a low voltage of −12 V. Index Terms-Flexible, organic light emitting diode (OLED), organic thin-film transistor (OTFT), plastic.

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Efficient electrophosphorescent polymer light-emitting devices have been developed using a Cs/Al cathode. The materials used were a molecularly doped poly(9-vinylcarbazole)-emissive layer with electrophosphorescent complexes: bis[2-(2′-benzothienyl)-pyridinato-N,C3′](acetylacetonate)Ir(III) as a red emitter, fac-tris(2-phenylpyridyl)Ir(III) as a green emitter, and bis[(4,6-difluorophenyl)-pyridinato-N,C2](picolinato)Ir(III) as a blue emitter. The red, green, and blue electrophosphorescent emitting devices exhibited efficient emissions of 4, 31, and 14 cd/A, respectively. An inspection of secondary ion mass spectroscopy (SIMS) profiles confirmed that Cs diffuses into both Al and the emissive layer. Also, a Cs concentration of approximately 1 atomic% was estimated to be present at the interface from x-ray photoelectron spectroscopy (XPS) profiles.

The band alignment at the interface between Pt and O-terminated ZnO(0001) was investigated by depositing Pt films on ZnO using X-ray photoelectron spectroscopy and ultra violet photoelectron spectroscopy in an ultrahigh vacuum system. Angle-resolved X-ray photoelectron spectroscopy measurement showed the band was bent down by 0.06 eV at the ZnO(0001) surface. The binding energy of Zn 2p doublet shifted toward higher values by 0.37 eV when Pt was deposited on ZnO(0001). The work function of ZnO(0001) was 4.08 eV and the valence band maximum measured by UPS on the clean ZnO(0001) surface was 2.82 eV. As a result, the Schottky barrier height of Pt/ZnO(0001) was 0.72 eV in this experiment.

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Interface bonding between alumina and various metals is discussed from the viewpoint of chemical thermodynamics. A method to predict the interface bonding species at an alumina/metal interface under equilibrium conditions is proposed by using the concept of chemical equilibrium for interface termination. The originality of this method is in the way a simple estimation of the interface binding energy, which is generally applicable to most metals, is developed. The effectiveness of this method is confirmed by careful examination of the experimental results. Comparison of the predicted and experimentally observed interface terminations reveals that the proposed method agrees well with the reported results. The method uses only basic quantities of pure elements and the formation enthalpy of oxides. Therefore, it can be applied to most metals in the periodic table and is useful for screening materials in the quest to develop interfaces with particular functions.

Time-of-flight spectra of CH4 molecules scattered from a LiF(001) surface have been obtained at various scattering angles by making use of a cross-correlation chopper blade for the [100] and [110] azimuthal directions. The incident translational energies of CH4 molecules are varied in the 190–500 meV range, while the target surface temperature is maintained at 300 K. The experimental results have been examined in relation to the washboard model [J. C. Tully, J. Chem. Phys. 92, 680 (1990)] which is modified here to take into account the speed distribution of incoming molecules. A qualitative agreement on their angular dependence has been obtained both in the mean speed and the energy spread of the scattered CH4 molecules, which reflects the effect of the strong corrugation of the sample surface. Their quantitative differences are partly explained by the translation-rotational excitation of CH4 molecules during collision.

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