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Moisture effect on electroluminescence characteristics, including current density versus voltage, luminance versus voltage, luminous efficiency versus current density, dark spot formation, and operational stability of organic light-emitting diodes, has been systematically investigated by exposing each layer of the devices to moisture at room temperature. Moisture has a different effect on each of the interfaces or surfaces, and the influence increases as exposure time increases. There is a slight effect on the electroluminescence characteristics after the anode surface has been exposed to moisture. However, severe luminance decrease, dark spot formation, and operational stability degradation take place after the light-emitting layer or the electron-transporting layer is exposed to moisture. It is also demonstrated that the effect of moisture can be substantially reduced if the exposure to moisture is in a dark environment. [ABSTRACT FROM AUTHOR]

Organic light-emitting diodes (OLEDs) are attractive for display applications because of their high brightness, low driving voltage, and tunable colon Their operating lifetimes, hundreds or thousands of hours, are sufficient for only a limited range of applications. The luminance efficiency decreases gradually as the device is operated (electrically aged), for reasons that are poorly understood. A prototypical OLED has the structure anodeHTLETL cathode, where the HTL and ETL are holeand electron-transporting layers, and the recombination and emission occur at or near the HTLETL interface. We find that the decreasing luminance efficiency is linearly correlated with an accumulation of immobile positive charge at the HTLETL interface, and the magnitude of the charge is comparable to the total charge at that interface when an unaged device is operated. A natural explanation of the connection between the two phenomena is that electrical aging either generates hole traps (and trapped holes) or drives metal ions into the device, and that either species act as nonradiative recombination centers. To estimate the accumulating immobile charge and determine its location, we use a variant of a recently introduced capacitance versus voltage technique. In the prototypical OLEDs described here, the HTL is a ca. 1000 Å layer of NPB, and the ETL is a 300-1800 Å layer of Alq[sub 3]. A device with an additional "emission layer" (EML) of an anthracene derivative between the HTL and ETL, in which the electroluminescence spectrum is characteristic of the EML, behaved similarly. We surmise that the phenomena reported here may be common to a wider variety of OLED structures and compositions. [ABSTRACT FROM AUTHOR]

Fabrication of polymer light-emitting diodes based on emission from the phosphorescent molecule fac tris(2-phenylpyridine) iridium doped into a poly(vinyl carbazole) host are reported. Several spin-coating solvents were evaluated for deposition of the polymer layer; toluene and chlorobenzene were found to consistently produce device-quality films with sufficient incorporation of the dopant. For single-layered devices with Mg[sub 0.9]Ag[sub[sub 0.1] cathodes, the luminance efficiency at 20 mA/cm² was measured to be 8.7 Cd/A for devices processed from chlorobenzene. This efficiency could be increased by over a factor of two with a trilayered device geometry consisting of the doped polymer layer, a hole-blocking layer, and electron transport layer. Further increases in efficiency, up to 30 Cd/A and 8.5% external quantum efficiency, were observed when a second dopant of 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole was added to the polymer emitter layer. [ABSTRACT FROM AUTHOR]

The electronic structure and chemistry of interfaces between tris-(8-hydroxyquinoline) aluminum (Alq[sub 3]) and representative group IA and IIA metals, Al, and Al/LiF have been studied by x-ray and ultraviolet photoelectron spectroscopies. Quantum-chemical calculations at the density functional theory level predict that the Alq[sub 3] radical anion is formed upon reaction with the alkali metals. In this case, up to three metal atoms can react with a given Alq[sub 3] molecule to form the trivalent anion. The anion formation results in a splitting of the N 1s core level and formation of a new feature in the previously forbidden energy gap. Virtually identical spectra are observed in the Al/LiF/Alq[sub 3] system, leading to the conclusion that the radical anion is also formed when all three of these constituents are present. This is support by a simple thermodynamic model based on bulk heats of formation. In the absence of LiF or similar material, the reaction of Al with Alq[sub 3] appears to be destructive, with the deposited Al reacting directly with the quinolate oxygen. We proposed that in those circumstances where the radical anion is formed, it and not the cathode metal are responsible for the electron injection properties. This is borne out by producing excellent injecting contacts when Ag and Au are used as the metallic component of the cathode structure. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents information on a study which constructed electroluminescent devices using multilayer organic thin films. Methodology of the study; Results and discussion; Conclusions.

OBJECTIVE: N1-guanyl-1, 7-diaminoheptane (GC7), an inhibitor of deoxyhypusine synthase has been shown to exhibit significant anti-cancer activity. However, the biological role of eukaryotic translation initiation factor 5A2 activation (EIF5A2) and GC7 on drug resistance in non-small cell lung cancer (NSCLC) has not been investigated. In this study, we aimed to investigate the therapeutic effect of GC7 combined with cetuximab in NSCLC therapy. MATERIALS AND METHODS: The current study used cell viability assays, EdU incorporation assays, and western blot to detect that the GC7 exhibited synergistic cytotoxicity with cetuximab in NSCLC. RESULTS: CCK-8 assays showed that combined treatment with GC7 and cetuximab significantly inhibited the viabilities in three NSCLC cell lines. In addition, EdU incorporation assays also indicated that GC7 co-treatment remarkably enhanced the cetuximab sensitivity in NSCLC cells. Nevertheless, down-regulation of EIF5A2 diminished the regulatory role of GC7 in cetuximab cytotoxicity. Western blot showed that transfection of EIF5A2 siRNA significantly suppressed the protein expression of EIF5A2 in NSCLC cells. CONCLUSIONS: These findings demonstrate that combined treatment with GC7 could enhance cetuximab sensitivity by inhibiting EIF5A2 in NSCLC cells, implying the potential clinical application of GC7 in cetuximab-based chemotherapy for NSCLC patients. [ABSTRACT FROM AUTHOR]