New Alq3 derivatives with efficient photoluminescence and electroluminescence properties for organic light-emitting diodes

Tris(β-ketoiminate) Aluminium(III) Compounds as Aluminium Oxide Precursors

Precursor design is the crucial step in tailoring the deposition profile towards a multitude of functional materials. Most commercially available aluminium oxide precursors require high processing temperatures (>500 °C). Herein, we report the tuning of the decomposition profile (200-350 °C) of a range of octahedrally coordinated tris(β-ketoiminate) aluminium complexes of the type [Al(MeCN(R)CHC=OMe)₃ ], by varying the R substituents in the ligands. The complexes are derived from the reaction of trimethylamine alane (TMAA) and a series of N-substituted β-ketoiminate ligands (R-acnacH, R=Me, Et, ⁱ Pr, Ph) with varying R-substituents sizes. When the more sterically encumbered ligand (R=Mes) was used, the Al atom became five-coordinate, therefore representing the threshold to octahedral coordination around the metal in these type of compounds, which, consequently, lead to a change of decomposition profile. The resulting compounds have been characterised by NMR spectroscopy, mass spectrometry, elemental analysis and single crystal X-ray diffraction. [Al(MeCN(Me)CHC=OMe)₃ ] has been used as a single source precursor for the deposition of Al₂ O₃ . Thin films were deposited via aerosol assisted chemical vapour deposition (AACVD), with toluene as the solvent, and were analysed using SEM, EDX and XPS.

Si(bzimpy)2 – a hexacoordinate silicon pincer complex for electron transport and electroluminescence

We demonstrate the feasibility of hexacoordinate silicon complexes with dianionic pincer ligands as electron transport and electroluminescent components of organic electronic devices.

Thermal, dielectric characteristics and conduction mechanism of azodyes derived from quinoline and their copper complexes

A novel series of (5-(4'-derivatives phenyl azo)-8-hydroxy-7-quinolinecarboxaldehyde) (AQLn) (n=1, p-OCH3; n=2, R=H; and n=3; p-NO2) and their complexes [Cu(AQLn)2]·5H2O are synthesized and investigated. The optimized bond lengths, bond angles and the calculated quantum chemical parameters for AQLn are investigated. HOMO-LUMO energy gap, absolute electronegativities, chemical potentials, and absolute hardness are also calculated. The thermal properties, dielectric properties, alternating current conductivity (σac) and conduction mechanism are investigated in the frequency range 0.1-100kHz and temperature range 293-568K for AQL1-3 and 318-693K for [Cu(AQL1-3)2]·5H2O complexes. The thermal properties are of ligands (AQLn) and their Cu(II) complexes investigated by thermogravimetric analysis (TGA). The temperature and frequency dependence of the real and the imaginary part of the dielectric constant are studied. The values of the thermal activation energy of conduction mechanism for AQLn and their complexes [Cu(AQLn)2]·5H2O under investigation are calculated at different test frequencies. The values of thermal activation energies ΔE1 and ΔE2 for AQLn and [Cu(AQLn)2]·5H2O decrease with increasing the values of frequency. The ac conductivity is found to be depending on the chemical structure of the compounds. Different conduction mechanisms have been proposed to explain the obtained experimental data. The small polaron tunneling (SPT) is the dominant conduction mechanism for AQL1 and its complex [Cu(AQL1)2]·5H2O. The quantum mechanical tunneling (QMT) is the dominant conduction mechanism for AQL2 and its complex [Cu(AQL2)2]·5H2O. The correlated barrier hopping (CBH) is the dominant conduction mechanism for AQL3 and its complex [Cu(AQL3)2]·5H2O, and the values of the maximum barrier height (Wm) are calculated.

Synthesis and photophysical properties of aluminium tris-(4-morpholine-8-hydroxyquinoline)

Aluminium tris(4-morpholinyl-8-hydroxyquinoline) has been synthesized and characterized. The photoluminescence measurements showed that the new derivative is blue shifted and has relative photoluminescence quantum yield two times higher compared to the pristine Al tris(8-hydroxyquinoline). Deferential scanning colorimetric studies revealed that the newly synthesized Alq3 derivative in this work is amorphous material with the highest transition glass temperature value among the reported amorphous Alq3 derivatives.