We report the charge generation layer (CGL) structure comprising of Li2CO3 doped bathocuproine (BCP:Li2CO3)/MoO3 doped 4,4-N,N-bis [N-1-naphthyl-N-phenyl-amino]biphenyl (NPB:MoO3)/MoO3 doped 4,4′-N,N′-dicarbazole-biphenyl (CBP:MoO3) for tandem organic light emitting diodes (TOLEDs). Compared to the TOLED using the conventional CGL structure of BCP:Li2CO3/20 nm CBP:MoO3, the one using the CGL structure of BCP:Li2CO3/5 nm NPB:MoO3/15 nm CBP:MoO3 showed increased electrical and luminous properties, mostly because the introduction of the higher-conductivity NPB:MoO3 relative to CBP:MoO3 could improve the current conduction in the CGL structure. Whereas, the performance of the CGL structure of BCP:Li2CO3/x nm NPB:MoO3/20- x nm CBP:MoO3 decreased with x increasing, mostly due to the fact that the CBP:MoO3 became depleted of mobile holes upon contacting p-doped NPB: the smaller thickness of CBP:MoO3, the worse conductivity for it. We provide some in-depth insights on designing the high-performance CGLs for TOLEDs.

The characteristic parameters of initiating defects in HfO2/SiO2 high-reflector film at wavelength of 1064 nm are investigated through the combined application of laser-conditioning process and the multispot damage threshold test. The laser damage tests before and after laser-conditioning are carried out within three different spot diameters. The damage threshold and the density are considered to characterize the initiating defects which are shown to be susceptible to laser damage. These characteristic parameters are obtained through fitting the damage data with the spot size effect. The influence of laser-conditioning effect on the initiating defects is analyzed. The initiating defects are specified by a Gaussian distribution after laser-conditioning. It is discussed the essential roles of the initiating defects to the damage threshold of the film. The investigation on characteristic parameters of initiating defects has potential to be applied in the mechanisms of laser induced damage and laser-conditioning, as well as in the direction the preparation of the films.

We reported material characterization of the nano-structured TiO2 thin films prepared by the sol-gel dip-coating process on glass substrates. The dependence of the structural, morphological and optical properties of the synthesized films on the fabrication parameters such as withdrawal velocity and annealing temperature were investigated by the techniques of X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV-visible spectrophotometry. The results indicate that for the TiO2 films annealed at 500 °C there exhibits (1 0 1) XRD peak corresponding to the anatase phase of TiO2. The latter is consistent with the recorded Raman signal observed at 142 cm-1 (Eg mode) and 391 cm-1 (B1g mode), respectively. From the analyses made on the SEM micrographs and AFM images, it was revealed that the morphology and surface roughness of the thin films would depend on the withdrawal speed and the heat treatment temperature. The UV-visible spectroscopy analyses show that all the films were transparent in the visible region with an average transmittance of more than 70%. With an increase on the dip-coating speed from 1 cm/min to 3 cm/min, we observed a spectral red shift of the absorption edge from 3.76 eV to 3.71 eV, indicating a decrease in the bandgap energy (Eg) of the films.

Hydrogen doping in the bulk of anatase TiO2 was studied by density functional theory approach. Our results show that hydrogen atom prefers the interstitial sites which are closer to the oxygen atoms. Investigation of the electronic structures of different hydrogen doped systems indicates the increment of Fermi energy and bond length, affecting the instability of the system. Hydrogen doping in the anatase TiO2 structure injects electron in the lower region of the conduction band, around the Ti states, leading Ti4+ toward Ti3+, while having no effect on the band gap energy value of TiO2. Therefore, the observed hydrogen induced band gap narrowing in TiO2 samples could be due to the structural disorders generated in the hydrogenation process. The hydrogen storage capacity of approximately 3 H atoms per supercell (Ti32O64) is also obtained, which is promising for renewable energy storage issue.

The dynamical processes of a low-energy carbon ion collision with the graphene sheet supported by diamond at three impact positions are studied by using empirical potential molecular dynamics simulations. The energy transformation and the structural evolution have been studied. Five types of processes are observed: adsorption, hybridization, defects formation in diamond, atom emission and transmission. We find that the irradiation damage is closely related to the incident energy and impact position. In our simulations, as the projectile collides at a graphene atom, it transfers most of its energy to the primary knock-on atom, and defects are created in graphene. When the projectile moves perpendicular towards the center of a C-C bond in the graphene sheet, the energy transferred from the projectile to the atoms associated with the bond increases firstly and then decreases with the increasing incident energy, and the graphene sheet remains two-dimensional crystal structure after collision when the incident energy is larger than 360 eV. While the impact location is the center of a hexagonal ring on the graphene sheet, the energy transferred from the projectile to the atoms of the target ring is very small regardless of how large is the incident energy, and the graphene sheet is able to keep perfect crystal structure when the incident energy is larger than 34 eV.

We propose a comprehensive description of the strain configuration induced by the lattice mismatch in a core-shell nanowire with circular cross-section, taking into account the crystal anisotropy and the difference in stiffness constants of the two materials. We use an analytical approach which fully exploits the symmetry properties of the system. Explicit formulae are given for nanowires with the wurtzite structure or the zinc-blende structure with the hexagonal/trigonal axis along the nanowire, and the results are compared to available numerical calculations and experimental data on nanowires made of different III–V and II–VI semiconductors. The method is also applied to multishell nanowires, and to core-shell nanowires grown along the 〈0 0 1〉 axis of cubic semiconductors. It can be extended to other orientations and other crystal structures.

In this work, optical properties of colloidal silica crystals are investigated theoretically. Numerical calculations are discussed and compared to experimental measurements. The existence of photonic band gap (or stop band) is inferred by analyzing the transmission spectra and dips of low transmission are typically correlated with photonic band gaps. The position of the main dip in simulated spectra matches the pseudo photonic band gap expected by the calculated photonic band gap diagram. Positions of stop band show a strong dependence on the diameter of silica spheres. We note that positions of the main dips deduced from simulated and measured spectra are very near. Good agreement between measured and theoretical results is then reported.

Microstrip ring resonator (MSRR) is an efficient technique for electromagnetic material characterization in microwave bands. Ferrites constitute important class of materials for microwave devices, especially for RF passive components. The aim of the work was to characterize ferrite materials using the frequency response of MSRRs. A theoretical analysis of the problem has been developed to find a relation between the ring resonance frequencies and the electromagnetic properties of ferrite such as effective permittivity and permeability. The measurements made on YIG (101) from 1 to 30 GHz are found to be in good agreement with the theoretical results. And the MSRR technique applied on ferrite materials has been validated.

The author reports that the spatial luminescent distribution from Cu substrate is in special sync with the Cu substrate morphology in terms of suspended formation of the deposited graphene fabricated via chemical vapor deposition. Moreover, the Raman 2D and G peak position of the graphene relatively shift to high frequency on the even Cu foil domain, showing more compressive strain than the uneven region. The author can reveal that the reducing compressive strain by virtue of the uneven Cu domains in order to minimize the interaction between graphene and Cu substrate has one of the important roles in forming suspended graphene. Current mapping in small dimension additionally shows that the current flow is mostly detected at the nano-terrace regions than the even, further substantiating the significance of the detailed underlying Cu substrate morphology. The author can also shows the correlation between the graphene strain revealed via 2D peak shift on Cu surface and the sheet resistance value of graphene on PET substrate, suggesting the degree of suspended formation of the graphene on Cu may be one of the important factors in increasing electrical performance on PET substrate.

The paper presents the measurement and computation of the corona onset voltages, electric field and ion current density profiles of a new “Tri-electrode system” intended for electrostatic separation applications. Unlike the well-known “dual cylinder-wire electrode system”, the new system utilizes an extra adjustable wire in order to provide the means for a more efficient ion charging current; necessary for separation of different granular mixtures. An experimental setup is constructed to model the present multi-electrode arrangement. The measurements are carried out for wire diameters between 0.3–1.0 μm and for different geometrical parameters. Without resorting to the commonly used Deutch’s assumption, a computational scheme is developed to solve the corona equations and to compute the associated ionized field quantities of the system. Mapping of the ion flow field patterns demonstrates the impact of this assumption on the solution’s accuracy. The computed results were found to be in good agreement with experiments. The configuration offers a more efficient charging process and separation in comparison with earlier separators’ designs.

The behaviour of DC corona discharge in air that is free of particulate matter with the wires-to-plane geometry was analysed in this work. The formulae I = KV (V − V0) and I = A (V − V0)m commonly used for the current-voltage characteristics were used to determine the various corona parameters for the two polarities of the corona discharge. Using curve fitting, it has been shown that the geometric factors K and A and the exponent m are strongly affected by the number n of the discharging wires. However, the corona inception voltage determined from the measurements is weakly influenced when n is small, and it remained constant for n > 5 discharging wires. As for the breakdown voltage of the discharge, it is practically independent of the number n. Furthermore, it was verified that the two formulae above can be used for both negative and positive corona in multiple wires-to-plane geometries.

The scanning of parts in eddy current testing can lead to a large amount of measurement data (predictors). Partial least square (PLS) regression is a mean to reduce the dimensionality of the subsequent inverse problem by projecting the predictors in a latent subspace of reduced dimension maximizing the covariance between the projection and the responses which have to be estimated. In a second step, a regression model is elaborated linking the responses to the latent variables. PLS was originally developed in the field of chemical analysis. In this paper, the PLS method is applied in the field of eddy current testing for the characterization of minute cracks. It is tested firstly on simulated data and then on experimental data. It is found that the reconstruction of the area of minute cracks is made possible by PLS.

Numerical and experimental investigations of a broadband vibration energy harvester with triple-well are presented. The nonlinear restoring force of the tristable oscillator is experimentally identified as a high order polynomial that depends on the relative spacing and locations of the magnets in the magnetically coupled piezoelectric cantilever. Simulations and experiments are performed at different harmonic excitation levels ranging from 10 to 35 Hz. The tristable energy harvester possesses the unique jump characteristics of oscillation center stemming from excitation level and initial displacements. Its broad frequency range of 15.1–32.5 Hz is obtained from the transition among three wells. It is also demonstrated that the tristable nonlinear oscillator will be more helpful to improve the broadband performance for harvesting vibration energy under low frequency excitations.

The extended Korteweg-de Vries (eKdV) equation is an important model for the description of internal solitary waves (ISWs) in shallow seas. The N-soliton solution of the eKdV equation is investigated by Hirota bilinear method. Direct simulation of the eKdV equation is performed for several ISWs phenomena including polarity conversion, packets and collisions by virtue of the N-soliton solution. Synthetic aperture radar (SAR) image simulations of those phenomena are also presented. Furthermore, the comparison between the simulated SAR image and the observed SAR image in the South China sea is provided, which shows that the N-soliton solution may describe various ISWs phenomena.