Huimin Yuan

Structures and photoluminescence properties of Alq3 1D materials prepared by an extremely facile solution method

Ultra-long crystalline Alq3 1 dimensional (1D) materials were prepared by using an extremely facile solution approach without any surfactant, SDS, anti-solvent, or other reagents. The Alq3 1D materials have smooth surfaces and pentagonal or hexagonal cross-sections. The length of the microrods have α-phase crystalline structures. The prepared Alq3 samples exhibit excellent green-light photoluminescence (PL) performance. The growth mechanism of the Alq3 1D structures were discussed. The limitation conditions of the Alq3 microrods were also studied. In addition, the influence of the volume of CHCl3 on the microrods was discussed. This controllable growth method can potentially be extended to other functional organic nanomaterials.

The structure of Mn-doped tris(8-hydroxyquinoline)gallium by extended x-ray absorption fine structure spectroscopy and first principles calculations

Metal-Mqx (M = Al, Ga, Zn, Be, and Ca, x = 2 or 3) complexes play a key role in organic spintronics and organic optoelectronics. However, the accurate structure determination of these complexes has been a challenge for a long time. Here, we report the structure of Mn-Gaq3 investigated by using first-principle density functional theory (DFT) calculations and extended X-ray absorption fine structure (EXAFS) spectroscopy. First, the structures of Mn-Gaq3 were predicted by first-principle DFT calculations. Then, all reasonable structures achieved from the calculations were used to fit the EXAFS spectra. By this method, the structure of Mn-Gaq3 is well obtained. We believe this method is also applicable to other metal-Mqx films.

Room temperature ferromagnetic properties of dysprosium-doped tris(8-hydroxyquinoline) aluminum: experimental and theoretical investigation

Room temperature ferromagnetism was observed in rare earth dysprosium (Dy)-doped tris(8-hydroxyquinoline) aluminum (Alq3) organic small molecular films. The Dy-doped Alq3 films were prepared by co-evaporating pure Alq3 and Dy powders on Si substrates in a vacuum. The maximum room temperature coercive field and the saturation magnetization are about 70 Oe and 9.5 × 10−6 emu, respectively. The structures were studied by the atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and synchrotron radiation X-ray absorption fine structure (XAFS). The magnetic properties were investigated by the MicroMag Alternating Gradient Magnetometer (AGM), Quantum Design superconducting quantum interference device (SQUID) and first-principles calculations. The room temperature ferromagnetism is ascribed to the magnetic moments induced by the Dy atom and the large energy difference between ferromagnetic and antiferromagnetic coupling.

Self-assembled tubular nanostructures of tris(8-quinolinolato)gallium(III)

We report for the first time the controllable growth of tubular nanostructures at the nanoscale of the broadly applied organic drug material, tris(8-hydroxyquinoline)gallium (Gaq3), by an extremely facile approach. The products show a relatively low turn-on field (8.5 V μm−1) and a very high maximum current density (2.3 mA cm−2). The length of the Gaq3 tubes and nanostructures can be readily manipulated and the adopted method is highly transferrable to other organic materials.

Structural properties of Alq3 nanocrystals prepared by physical vapor deposition and facile solution method

Tris(8-hydroxyquinoline) aluminum (Alq3) nanostructures are promising materials for nanooptoelectronic devices and molecular spintronics. In this paper, we report Alq3 nanocrystals prepared by both physical vapor deposition (PVD) and facile solution method. The transmission electron microscopy (TEM) and high resolution scanning electron microscope (SEM) measurements show that the Alq3 nanomaterials prepared by PVD technique are e-Alq3 nanoflowers, while the Alq3 nanostructures prepared by solution method are α-Alq3 nanorods. Our experiments indicate that the α-Alq3 nanomaterials prepared by using solution method are more suitable for the fabrication of molecular spintronic devices than that of PVD method.

Effect of oxygen on the magnetic property of Bis(8-hydroxyquinoline)copper (CuQ2): An experimental and theoretical study

The magnetic properties of bis(8-hydroxyquinoline)copper (CuQ2) were investigated by experiments and first-principles density functional theory (DFT) calculations. The as-prepared CuQ2 film shows paramagnetic behavior. After annealing in air, room temperature ferromagnetic (FM) properties were found in CuQ2 film. The Fourier transform infrared spectroscopy (FTIR) analysis indicates a new vibrational mode related to out of plane O–H bend in the annealed film. DFT calculations show that the energy difference between the FM and the antiferromagnetic (AFM) states is greatly increased after O doping, which may be responsible for the room temperature ferromagnetism in the annealed CuQ2 film.

Cu-induced spin polarization in tris(8-hydroxyquinoline) aluminum

Cu-induced spin polarization in tris(8-hydroxyquinoline) aluminum (Alq3) has been studied by first-principles calculation. The entanglement between an electron transfer from Cu to Alq3 and a structural distortion of the Alq3 molecule gives rise to a strong spin polarization in this originally nonmagnetic molecule Alq3. The calculated total magnetic moment mainly resides on the Alq3 molecule (0.6 μB), while that on Cu is moderate (0.4 μB). The finding of a spin polarization induced by the nonmagnetic element Cu is helpful for understanding of spin-related phenomenon in Alq3 and potentially enabling future magnetic-metal-free organic spintronics.