Iain W. H. Oswald

A non-doped phosphorescent organic light-emitting device with above 31% external quantum efficiency.

The demonstrated square-planar Pt(II)-complex has reduced triplet-triplet quenching and therefore a near unity quantum yield in the neat thin film. A non-doped phosphorescent organic light-emitting diode (PhOLED) based on this emitter achieves (31.1 ± 0.1)% external quantum efficiency without any out-coupling, which shows that a non-doped PhOLED can be comparable in efficiency to the best doped devices with very complicated device structures.

Water Cluster Confinement and Methane Adsorption in the Hydrophobic Cavities of a Fluorinated Metal–Organic Framework

Water cluster formation and methane adsorption within a hydrophobic porous metal organic framework is studied by in situ vibrational spectroscopy, adsorption isotherms, and first-principle DFT calculations (using vdW-DF). Specifically, the formation and stability of H2O clusters in the hydrophobic cavities of a fluorinated metal-organic framework (FMOF-1) is examined. Although the isotherms of water show no measurable uptake (see Yang et al. J. Am. Chem. Soc. 2011 , 133 , 18094 ), the large dipole of the water internal modes makes it possible to detect low water concentrations using IR spectroscopy in pores in the vicinity of the surface of the solid framework. The results indicate that, even in the low pressure regime (100 mTorr to 3 Torr), water molecules preferentially occupy the large cavities, in which hydrogen bonding and wall hydrophobicity foster water cluster formation. We identify the formation of pentameric water clusters at pressures lower than 3 Torr and larger clusters beyond that pressure. The binding energy of the water species to the walls is negligible, as suggested by DFT computational findings and corroborated by IR absorption data. Consequently, intermolecular hydrogen bonding dominates, enhancing water cluster stability as the size of the cluster increases. The formation of water clusters with negligible perturbation from the host may allow a quantitative comparison with experimental environmental studies on larger clusters that are in low concentrations in the atmosphere. The stability of the water clusters was studied as a function of pressure reduction and in the presence of methane gas. Methane adsorption isotherms for activated FMOF-1 attained volumetric adsorption capacities ranging from 67 V(STP)/V at 288 K and 31 bar to 133 V(STP)/V at 173 K and 5 bar, with an isosteric heat of adsorption of ca. 14 kJ/mol in the high temperature range (288-318 K). Overall, the experimental and computational data suggest high preferential uptake for methane gas relative to water vapor within FMOF-1 pores with ease of desorption and high framework stability under operative temperature and moisture conditions.

High efficiency warm-white organic light emitting diodes from a single emitter in graded-doping device architecture

We report high efficiency single-emitter white organic light emitting diodes (SWOLEDs) from a phosphorescent platinum-pyridyltriazolate complex. We have demonstrated good control of the recombination zone and its impact on device performance by adjusting the number of emissive layers, their thicknesses and relative positions in the device stack. Device optimization has resulted in SWOLEDs with a peak power efficiency (PE) = 30.4 ± 1.3 lm/W, external quantum efficiency = 17.0% ± 0.1%, and correlated color temperature = 3450 K, within acceptable warm-white range despite the color rendering index being only 62. The devices exhibit negligible performance roll-off at 500–1000 cd/m2.

Correlated states in β-Li2IrO3 driven by applied magnetic fields

Honeycomb iridates are thought to have strongly spin-anisotropic exchange interactions that could lead to an extraordinary state of matter known as the Kitaev quantum spin liquid. The realization of this state requires almost perfectly frustrated interactions between the magnetic Ir

The proof is in the powder: revealing structural peculiarities in the Yb3Rh4Sn13 structure type

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Multi-Faceted Scientific Strategies Toward Better Solid-State Lighting of Phosphorescent OLEDs

ions, but small imbalances in energy make other ordered states more favorable. Indeed, the closeness in energy of these ordered states is itself a signature of the intrinsic frustration in the system. In this work, we illustrate that small magnetic fields can be employed to drive the frustrated quantum magnet

Exciton and Polaron Quenching in Doping-Free Phosphorescent Organic Light-Emitting Diodes from a Pt(II)-Based Fast Phosphor

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Doping-Free Organic Light-Emitting Diodes with Very High Power Efficiency, Simple Device Structure, and Superior Spectral Performance

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Hydrostatic pressure-induced modifications of structural transitions lead to large enhancements of magnetocaloric effects in MnNiSi-based systems

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Orientation of Organic Cations in Hybrid Inorganic–Organic Perovskite CH3NH3PbI3 from Subatomic Resolution Single Crystal Neutron Diffraction Structural Studies

IrO