Phosphorescent white organic light-emitting devices (WOLEDs) with a multilayer structure were fabricated, and colour stability was studied by manipulating electron transport property of the hole-blocking layer 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene (TPBi) and the electron transporting layer 4,7-diphenyl-1,10-phenanthroline (Bphen). With 20 nm thick TPBi and 20 nm Bphen tailoring electron transport, the WOLED yielded a slight Commission Internationale de l’Eclairage coordinates variation of (−0.003, 0.007) in a wide range of bias voltages. Additionally, a peak current efficiency of 32.4 cd/A and a peak external quantum efficiency of 12.7% were also realised. It was found that the enhancement of colour stability was due to optimisation of the electron transport, by adjusting the thicknesses of TPBi and Bphen to improve the charge carrier balance.

The emission of aligned dichroic dyes in a luminescent solar concentrator (LSC) illuminated from one side with collimated light results in a non-isotropic light distribution. We develop a model to describe emission profiles for dichroic dyes aligned at a general tilt angle with respect to a lightguide surface (including planar and homeotropic alignments) for various order parameters. We compare calculations with experimental results, demonstrating the dichroic nature of the dyes can have significant impact on the surface loss of luminescent solar concentrators. Including this dichroic nature is essential in correctly simulating the preferred edge emissions demonstrated experimentally in dyes aligned planarly on the surface of a lightguide.

AlInN thin films were synthesized on Si substrates by using stacked elemental layers (SEL) technique. Three stacking sequence Al/InN, Al/InN/Al/InN and Al/InN/Al/InN/Al/InN were prepared on Si (1 0 0) substrates by reactive RF sputtering of In target in Ar-N2 and DC sputtering of Al target in Ar atmosphere at room temperature. Annealing of the deposited stacks was carried out at 400 °C for 6 h in a three zone tube furnace. Structural properties of the annealed films were investigated using X-ray diffraction (XRD) whereas the surface analysis of the films was carried out using field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). XRD results show the formation of wurtzite AlInN thin films which become more obvious with increasing the stacked layers. FESEM analysis reveals drops-like polycrystalline films structure with randomly oriented grains whereas the AFM results show a decrease in the surface roughness with increasing stacking sequence. The formation of more prominent AlInN films with increase of stacking layers is attributed to a uniform interaction among the top and bottom Al and InN multilayers as a result of the annealing.

SnO2-Fe2O3 composite thin films were deposited on quartz substrate at 650 °C by pulsed laser deposition with Fe2O3 content varying between 0 and 50 wt.%. The effect of increasing Fe2O3 content on structural, optical and electrical properties of SnO2-Fe2O3 films were investigated. X-ray diffraction analysis indicates that the nature of deposited composite films can be tune from crystalline to amorphous with increase in the Fe2O3 content. X-ray photoelectron spectroscopy studies confirm the presence of SnO2 and Fe2O3 in the microstructure. Atomic force microscopy studies of the deposited films indicate that RMS roughness vary between 114.4 and 1.48 nm. The average optical transmittance decreases from 92 to 72% with increasing Fe2O3 content of the deposited films. The optical bandgap was decreased from 3.69 to 3.31 eV with increase in Fe2O3 content. The minimum resistivity was observed 3.71 × 10−2 Ω cm for the 30 wt.% Fe2O3 composite film. The low resistivity and high transmittance in the visible region enables these films suitable for optoelectronic applications.

ZnO nanopowders with different 3d transition metal (TM) doping (TM = Mn, Fe, Co, Ni) were synthesized by a new protocol based on slow hydrolyse of zinc acetate dissolved in methanol and supercritical drying in ethyl alcohol. The prepared Zn1−xTMxO (x = 0.25) nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), optical absorption and electron paramagnetic resonance spectroscopy (EPR). The results demonstrated that the TM dopant significantly affects the structural and magnetic properties of the samples. From the XRD spectra, the lattice parameters, average crystallite size and microstrain values were obtained. All ZnTMO nanoparticles show an expansion of the lattice parameters compared those of the bulk samples. Unit cell volume was minimized with Fe doping and increased as the atomic number of the dopant moved away from Fe. The XRD pattern indicates the formation of hexagonal wurtzite phase of ZnO for all the TM dopants. Electron microscopy characterization showed that the size of the Zn1−xTMxO particles is about 25 nm did not change significantly for the different dopants. Optical absorption measurements show that band gap energies of the TM-doped ZnO nanoparticles are around 3.2 eV. The Urbach energy of the ZnTMO nanopowders varies with the TM dopant. From magnetic measurements we observed the presence of room temperature ferromagnetic order in our TM-doped ZnO samples. EPR spectra confirm that TM ions were mainly incorporated as TM2+, occupying the Zn2+ sites in the wurtzite structure of ZnO. Room temperature ferromagnetic order was observed only in Ni- and Co-doped ZnO samples, whereas Mn- and Fe-doped powders showed only antiferromagnetic and paramagnetic interactions, respectively. The correlation between the structural and magnetic properties as a function of the TM dopant is discussed.

Crystallization of Lennard-Jones nanoparticles has been studied by molecular dynamics (MD) simulations. Spherical models with free surface are cooled from the melt to crystalline state. In the cooling process, thermodynamics, structural properties and atomic mechanism of the crystallization are investigated. We found that crystallization in nanoparticles follows the Ostwald’s step rule like that found in the past. Due to free surface contribution, the solidification exhibits non-homogeneous behavior which proceeds in different manners between core and surface: homogeneous crystallization in the core and heterogeneous one in the surface layer of nanoparticles. It is due to the discrepancy between structures of two parts: highly ordered structure dominates in the core region while the surface exhibits defective one with a high fraction of undercoordinated sites. Also, our results are consistent with previous ones about the free surface-induced phenomena.

The geometries, binding energies, electronic structures and magnetic properties of TMCn clusters (TM = Fe, Co, Ni, n = 9–15) have been systematically investigated with the generalized gradient approximation (GGA) based on all-electron density functional theory. Optimization results indicate that TMC9 clusters prefer linear structures with the TM atom at one end, while monocyclic planar structures are predicted to be the most favorable for TMCn (n = 10–15) clusters. The calculated second-order energy differences and fragmentation energies indicate that the magic numbers for stability appear at n = 10, 12, 14 for FeCn, and n = 11 and 14 for CoCn and NiCn, implying that these clusters possess relatively higher stability. Mülliken population analysis shows that charge always transfers from the TM atoms to C atoms. The magnetic moment of TMCn clusters mainly is located mainly on the TM atom. The 3d electrons in the TM atom play a dominant role in the determination of the magnetism of the TM atom.

TiO2 nanotubes were synthesized via electrochemical anodization of Ti foil at 60 V for 1 h in a bath with electrolytes composed of ethylene glycol containing 5 wt.% of NH4F and 1 vol.% of H2O2. The incorporation of optimum Cu2+ ions (1.30 at.%) into TiO2 nanotubes were prepared by using wet impregnation method to improve their photocatalytic methyl orange degradation and Pb(II) heavy metal removal. The small Cu2+ ions were successfully diffused into lattice of TiO2 nanotubes by conducting post-annealing treatment at 400 °C for 4 h in argon atmosphere after wet impregnation. In this manner, optimum Cu2+ ions played a crucial role in suppressing the recombination of charge carriers by forming inter-band states (mismatch of the band energies) within the lattice of Cu-TiO2. The experimental results showed that a maximum of 80% methyl orange removal and 97.3% Pb(II) heavy metal removal at pH 11 under UV irradiation for 5 h. Besides, it was noticed that photocatalytic Pb(II) heavy metal removal was strong dependence on pH of the solution because of the amphoteric character of Cu-TiO2 in an aqueous medium.

The resolution of classical imaging is limited by the Rayleigh diffraction limit, whereas ghost imaging can overcome this diffraction limit and enhance the resolution. In this paper, we propose a super-resolution thermal ghost imaging scheme based on deconvolution, which can further improve the imaging resolution. Because the traditional thermal ghost imaging result is the convolution between the original image of the object and the correlation function, we can use deconvolution algorithm to decrease the effect of convolution and enhance the imaging resolution. Actually, the correlation function of ghost imaging system is just the point spread function (PSF) of classical imaging system. However, PSF is hard to obtain in classical imaging system, and it is easy to obtain in ghost imaging system. So deconvolution algorithm can be easily used in the ghost imaging system, and the imaging resolution can increases 2–3 times in practice.

Nanostructured ZnO thin films with different precursor concentrations (0.5–0.8 M) have been deposited on glass substrates by sol-gel dip coating technique. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV-visible spectrophotometer, and m-lines spectroscopy have been employed to investigate the effect of solution concentration on structural, morphological, optical and waveguiding properties of the ZnO thin films. XRD spectra have shown that all the films are polycrystalline and exhibit the wurtzite hexagonal structure. SEM micrographs and AFM images have revealed that morphology and surface roughness of the thin films depend on sol concentration. The UV-visible transmittance results show a high transparency in the visible range and a shift of the maximum transmittance to the higher wavelength with increasing sol concentration. Waveguiding properties such as refractive index, number of propagating modes and attenuation coefficient measured at 632.8 nm wavelength by m-lines spectroscopy indicate that our ZnO slab waveguides are single mode and demonstrate optical losses estimated around 1.5 decibel per cm (dB/cm) for the thin film prepared with a sol concentration of 0.7 M.

The study is about the effect of H2 addition into N2 on the density of radiative species in the plasma and in the late afterglow of microwave flowing discharges at low gas pressure (2–10 torr). Intensities of radiative N2(B, C), N2+(B) neutral and ion molecules, H atoms and NH radicals were measured in the plasma and in the late afterglows for the N2(B) state. The results are discussed from the main kinetic reactions in the N2-H2 plasma and afterglow. From the intensity of N2, 1st pos. at 580 nm and after calibration by NO titration, the N-atom density in the afterglow can be determined. The variations of the N-atom density with H2 into N2 in the late afterglow are examined for several gas pressures (2–10 torr) at fixed microwave power (100 W) and flow rate (1 slm). The activity of the late afterglow has been measured on paper surfaces, outlining the influence of a few H2 into N2.

This paper studies the influence of inert gas additions He, Ar, Kr and Xe on breakdown voltage within dielectric barrier discharge reactor with oxygen feed gas. The density-normalized effective ionization coefficients αeff/N are calculated for inert gas/O2 mixtures, the critical reduced field E/Ncr is obtained where the electron ionization exactly balances the attachment. Adding inert gases would lead to the decreasing critical reduced field strength E/Ncr due to the enhancement of effective ionization coefficient. In addition, inert gas additions have shown to reduce the breakdown voltage. Moreover the numerical breakdown voltage values and the experimental data are plotted for the sake of comparison and results show that calculated results are in agreement with the experimental values. Parametric study offers substantial insight in plasma physics, as well as in ozone generation applications.

First principle calculations are employed scheme to investigate the electronic structures and mechanical properties of AlCu3 with divacancy defects using the pseudopotential plane wave method. The defect crystal is constructed by removing the nearest Al or Cu atoms to form the double point vacancies. Calculated lattice constants agree well with the experimental data. Moreover, structural stabilities of crystals containing divacancy are reduced. Results reveal that the crystal with double Cu vacancy defects is more stable than that of Al. Calculations of defect formation energies indicate that the divacancy of Cu is easier to exist in AlCu3. Divacancy defects play an important role to improve the mechanical properties of AlCu3 and corresponding ductility, stiffness and plasticity are increased. Furthermore, chemical bonds become weaker since the divacancy are introduced. Hybridizations between orbits of crystals are analyzed to account for the interactions in perfect and defect structures. Accordingly, implications of these findings on the mechanism of divacancy are discussed.

For a solution droplet in equilibrium with the atmospheric environment, a relationship exists between radius and concentration, which allows to express the saturation ratio of the droplet as a function of either one of these two parameters. The curves showing the complete behaviour of saturation ratio as a function of radius, for various sizes of NaCl nuclei, were previously presented for both wholly and partially dissolved salt. Here, the dependence of saturation ratio on droplet concentration, rather than on its radius, is examined and plotted for various NaCl nuclei. The occurrence of an analogous, but X-shaped, hysteresis phenomenon, characterizing the behaviour of the solution concentration in a growing-shrinking cycle of a solution droplet under changing humidity, is evidenced and discussed. An insoluble spherical core is assumed to be always present inside the condensation nucleus, so that the onset of the sudden salt re-crystallization is triggered at a well defined concentration value.

In this research the effect of electric field on two groups of wet and dry Pisum sativum seeds growth was studied. To generate the required electric field a parallel-plate capacitor with round copper plates of 30 cm diameter was used. The experiments were performed once in fixed exposure duration of 8 min in variable DC electric field of 0.25–1.5 kV/m. The other experiments were performed in variable fields of 50–125 kV/m in fixed exposure duration of 8 min, in two groups of AC and DC electric fields. The experiments were repeated three times. In each experiment 10 seeds were used and there was a sham exposed group for comparison, too. After application of electric field, the seeds were kept for six days in the same growth chamber with the temperature of 25 ± 1 °C and 12 h light/12 h darkness. On the 6th day length of stems and height of roots were measured. After doing statistical analysis, in low intensities of DC electric field, the highest significant increase of mean growth (The average of stem length and the height of roots) was seen in 1.5 kV/m in wet seeds. In high intensities of DC and AC electric fields, the highest significant increase of mean growth was seen in AC electric field of 100 kV/m in wet seeds.