We report on highly efficient gas diffusion barriers for organic light emitting diodes (OLEDs). Nanolaminate (NL) structures composed of alternating Al2O3 and ZrO2 sublayers grown by atomic layer deposition at 80 °C are used to realize long-term stable OLED devices. While the brightness of phosphorescent p-i-n OLEDs sealed by a single Al2O3 layer drops to 85% of the initial luminance of 1000 cd/m2 after 1000 h of continuous operation, OLEDs encapsulated with the NL retain more than 95% of their brightness. An extrapolated device lifetime substantially in excess of 10 000 h can be achieved, clearly proving the suitability of the NLs as highly dense and reliable thin film encapsulation of sensitive organic electronic devices.

Surface defects on highly oriented pyrolytic graphite (HOPG) were controllably produced by bombardment with Cs+ ions at various incident kinetic energies ranging from 0.3 to 10 keV and at various dose densities. Defects in the HOPG created by Cs+ ion impacts were subsequently oxidized at 650 °C in air to produce nanometer-size monolayer and multilayer molecule corrals (pits). The controlled production of both monolayer and multilayer pits on HOPG bombarded with energetic Cs+ ions was realized and studied by scanning tunneling microscopy (STM). The pit density, pit yield, pit diameter, and pit depth can be well controlled by varying the experimental conditions. Multilayer pits can be controllably produced using Cs+ ion bombardment at higher kinetic energies, and monolayer pits can be produced using low-energy Cs+ ion bombardment. The presence of both monolayer and multilayer pits on the same HOPG samples makes the direct comparison of pit growth rates possible under exactly the same conditions. The measured depth-resolved pit growth rates for multilayer pits are in good agreement with a model of the pit growth rate “acceleration” by adjacent layers, and the separate contributions to the pit growth rate of surface diffusion and collision were extracted.

We report the design and characterization of three heteroleptic orange-red phosphorescent iridium(III) complexes bearing two 2-(4-fluorophenyl)-3-methyl-quinoxaline (fpmqx) cyclometalated ligands combined with three different ancillary ligands, triazolylpyridine (trz), picolinate (pic), and acetylacetonate (acac). All of these complexes emit an orange to red color in the spectral range of 605-628 nm in dichloromethane. Strong spin-orbit coupling of the iridium atom allows the formally forbidden mixing of singlet and triplet states. Because of the structureless phosphorescent line shapes and low Stokes shifts between triplet metal-to-ligand charge-transfer ((3)MLCT) absorption and phosphorescent emission, we propose that emission originates predominantly from the (3)MLCT state with a lesser admixture of totally ligand-based (3)(pi-pi*) states. The influence of 5d-electron densities of the iridium center on highest occupied molecular orbitals leads to high emission quantum yields in toluene (Phi(p) = 0.39-0.42) and to short triplet lifetimes. Cyclovoltammetry measurements show reversible oxidation peaks from 0.74 to 0.92 V and reversible reduction waves with potentials ranging from -1.58 to -2.05 V versus Cp(2)Fe/Cp(2)Fe(+). All complexes have been applied in simple test devices and also in stable, long-living devices to evaluate their electroluminescent device performances, for which we especially report the influence of the chosen ancillary ligands on emission colors, efficiencies, and device lifetimes. We obtained narrowband emission ranging from 613 to 630 nm with a full width at half-maximum of 64-71 nm, and a maximum in power efficiency of eta(p) = 14.6 lm/W at a current density of J = 0.01 mA/cm(2) for [(fpmqx)(2)Ir(pic)]. The operating lifetimes of [(fpmqx)(2)Ir(trz)] in both neat and mixed matrixes were longer than that of the established stable tris(1-phenylisoquinolinato)iridium(III) [Ir(piq)(3)]. From the lifetime measurements, it becomes clear that the stability is strongly correlated to the type of ancillary ligand. An extrapolated lifetime of 58 000 h with an initial brightness of 1000 cd/m(2), together with a very low voltage increase of 0.2 V over a time period of 1000 h (starting voltage of 4.1 V), was achieved. Such a high device lifetime is attributed to the chemical stability of all materials toward both charge carriers and excitons.

In an attempt to synthesize a novel homoleptic complex 3 from 2-methyl-3-phenylquinoxaline 1 and Ir(acac)(3) for application as a triplet emitter in OLEDs (organic light-emitting diodes) no cyclometalation was observed. Instead, an annulation to 1-methyl-4-phenylpyrrolo[1,2-a]quinoxaline 2 was observed. Since pyrroloquinoxalines are potentially bioactive and few paths for their synthesis are known, selected reactions and conditions were investigated, suggesting Ir(acac)(3) as catalyst and proving glycerol to be a reactant.

The reaction of 2-(3-methylbiphenyl-2-yl)pyridine with IrCl(3).nH(2)O in the presence of water incorporates a tightly bonded CO at the iridium center; in the subsequent reaction with picolinic acid a complex revealing an unusual CH activation of a methyl group is formed.