Single crystals of orthorhombic black phosphorus can be grown by a short way transport reaction from red phosphorus and Sn/SnI 4 as mineralization additive. Sizes of several millimeters can be realized with high crystal quality and purity, making a large area preparation of single or multilayer phosphorene possible. An in situ neutron diffraction study has been performed addressing the formation of black phosphorus. Black phosphorus is formed directly via gas phase without the occurrence of any other intermediate phase. Crystal growth was initiated after cooling the starting materials down from elevated temperatures at 500 °C. Highlights:-Large black phosphorus crystals were grown by a short way transport reaction -In situ neutron diffraction affirm the formation of black P directly from gas phase -Large crystals can be used as starting material for phosphorene synthesis

We present direct evidence for stable oligomers in vacuum-deposited thin films of zinc(II) bis(8-hydroxyquinoline) (Znq(2)). The tetramer [(Znq(2))(4)] is the energetically favored configuration in both the single crystal and the vacuum-deposited thin film. Oligomerization leads to distinct, symmetry-driven differences between the electronic states in Znq(2) and those in the archetypal organic electroluminescent molecule tris(8-hydroxyquinoline) aluminum (Alq(3)). In the case of the Znq(2) tetramer, symmetry leads to an extended network of overlapping pyridyl and phenolato moieties in the solid film. Analysis of the electronic structure of (Znq(2))(4) calculated by ab initio Hartree-Fock (HF) methods reveals a localization and energy shift of high-lying occupied and low-lying unoccupied states on symmetry related ligands located on opposite sides of the supramolecular structure resulting in a dipole moment for (Znq(2))(4) tetramer close to zero. The optimal pi-overlap pathways, altered charge distributions, and extended electronic states of tetrameric Znq(2) may be expected to enable low operating voltage organic light-emitting devices (OLEDs) based on Znq(2). We present preliminary evidence that the operating voltage of (Znq(2))(4)-based OLEDs is indeed lower than that of identical devices made with Alq(3). Strategic substitution of 8-hydroxyquinoline ligands and control of the structural symmetry of the corresponding metal chelates may offer a route to high efficiency and low operating voltage small molecule OLEDs.

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The luminescence of Eu(2+) in hydride and deuteride perovskite hosts LiMH3 and LiMD3 (M = Sr, Ba) is reported. Bright yellow (M = Sr) and green (M = Ba) emission is observed and assigned to 4f(6)5d-4f(7) emission from Eu(2+) in the highly symmetric 12-coordinated M(2+) site (m3[combining macron]m). The long wavelength of the emission is explained by the strong covalence and crystal field splitting in europium's coordination by hydride anions. A well-resolved vibrational structure in the emission and excitation spectra of Eu(2+) in the Sr-compounds allows for an accurate determination of the energy of the lowest 4f(6)5d state and vibrational frequencies, for both the hydride and deuteride. The isotope effect on the energy of the fd states is small (∼70 cm(-1)), as expected. Surprisingly, also the vibrational energies observed in the vibronic progression are similar for the d-f emission spectra in LiSrH3 and LiSrD3. This is explained by strong coupling of the d-f emission with low energy acoustic phonons which, contrary to optical phonons, are not strongly affected by replacing H by D. The present results provide insight into the long wavelength Eu(2+) emission in hydride coordination and the influence of isotope replacement on the luminescence.