We report an increase of electroluminescence ͑EL͒ efficiency by two orders of magnitude for poly͑2-methoxy-5-͑2Ј-ethylhexyloxy͒-1,4-phenylene vinylene͒ ͑MEH-PPV͒ based polymer light-emitting diodes ͑PLED͒ while employing Al as the cathode with an ultrathin layer of poly͑ethylene oxide͒ ͑PEO͒. EL efficiencies of MEH-PPV PLEDs biased at 10 mA were found to be 0.017 cd/ A at 31 cd/ m 2 , 1.50 cd/ A at 2515 cd/ m 2 , and 4.96 cd/ A at 8416 cd/ m 2 for applying Al, PEO/ Al, and PEO/ LiF/ Al as the device cathodes, respectively. The significant improvement in the device performance is attributed to the promotion of minority carrier injection ͑electrons͒, where the threshold of the injection can be characterized through the deviation of Fowler-Nordhiem tunneling prediction.

This work presents the fabrication of high-brightness (over 30000cd∕m2) top-emissive polymer light-emitting diodes (PLEDs) using a hybrid semitransparent cathode capable of efficient injection of electrons. The composite cathode is comprised of the organic oxide/Al complex as the injection buffer layer covered by a thin Ag overlayer. The anode is made of Ag:Ag2O coated on the glass substrate. The electroluminescence (EL) efficiency of 8.9cd∕A for phenyl-substituted poly(para-phenylene vinylene) copolymer based top-emissive PLED markedly exceeds that of 4.3cd∕A for the control device with the bottom-emissive configuration. The high performance is attributed to the balanced injection of charge carriers and the effective extraction of EL emission from the top cathode. The optical microcavity effect significantly promotes the EL emission in the direction along the surface normal.

When the wing is treated as a composite sandwich plate and it is assumed that the wing chordwise section is rigid, mathematical formulations for the stiffened composite multicell wing structures are provided, and associated governing equations for the aeroelastic divergence are also derived by a direct approach. When the matrix notation is used, the system of equations is written into an explicit and simple mathematical expression that can then be solved explicitly by using the technique of Laplace integral transform. In this modeling, the composite wing skins and stringers (including the spar anges) are simulated as the faces, whereas the spar webs and ribs are simulated as the core of the sandwiches. Because the wing cross section must have a streamline shape, unlike the usual uniform thickness modeling, it is more appropriate to simulate the wings as variable thickness sandwiches where the thickness is a function of the airfoil. Moreover, as is usual for assumptions for the sandwich plates, the effects of the transverse shear deformation are also considered. Because several special conditions have been studied in the literature, we rst compare our solutions with some existing solutions. To show the generality, several illustrative examples are given to consider the effects of spars, skins (including the ply orientation and stacking sequence), stringers, swept angles, aspect ratio, shape of airfoil, and the warping restraints on the divergence dynamic pressures and the lift loads redistribution.

This study addresses the feasibility of using an organic oxide/Al composite cathode to fabricate the small molecular organic light-emitting diodes (OLEDs). A supplementary organic buffer film is placed at the interface between the tris(8-hydroxyquinoline) aluminum (Alq3) and the organic oxide/Al complex layers. Incorporating the rubrene/poly(ethylene glycol) dimethyl ether (PEGDE) buffer layers into the composite cathode structure markedly improves the performance of devices. The luminous efficiencies of Alq3-based OLEDs biased at ∼100mA∕cm2 are 4.8 and 5.1cd∕A for rubrene (50Å)/PEGDE (15Å)∕Al and rubrene (50Å)/PEGDE (15Å)∕LiF (5Å)∕Al cathode devices, and 1.3 and 3.8cd∕A for devices with Al and LiF (5Å)∕Al cathodes, respectively.

No abstract