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Benefiting from their high concentration of in-plane nitrogen element, superior chemical/thermal stability, tunable electronic band structure and environmental friendly feature, graphite-like carbon nitride (g-C3N4) as a new promising metal-free material has drawn numerous attention in photo-/electric-catalysis. Comparing to the regulation of band structure in photocatalysis, the deliberately synthesis of g-C3N4 electrocatalysts is mainly focused on the construction of catalytic sites and the modulation of the charge transfer kinetics. Herein, this work reports a rapid method for synthesizing ultrafine g-C3N4 quantum dots (QDs) via electrochemical exfoliation using Al3+ ions. The uniform g-C3N4 QDs with smaller lateral dimension and thickness are collected due to the higher charge density and stronger electrostatic forces of Al3+ ions in the lattice of host materials as compared to the conventional univalent alkali cations. The as-obtained g-C3N4 QDs exhibit average lateral dimension and thickness of 3.5 nm and 1.0 nm, respectively, as determined by the TEM and AFM measurements. Also, the presence of the rich C/N defects is verified by the UV-vis spectra. Encouragingly, the ultrafine g-C3N4 QDs exhibit superior hydrogen evolution reaction (HER) performance with an ultra-low onset-potential closely approaching to 0 V, and a low overpotential of 208 mV at 10 mA/cm2, as well as a remarkably low Tafel slope (52 mV·dec-1) in acidic electrolyte. Taking the fabrication of the ultrafine g-C3N4 QDs with rich C/N defects as an example, this work provides a simple and feasible way to exfoliate 2D layered materials into low-dimensional nanomaterials towards highly-efficient electrocatalysis, as well as the exploration of their fascinating physic-chemical properties.

The flexible aluminum silicate nanofibers separators are prepared by electrospinning method. The results suggest the presence of amorphous phase in aluminum silicate fibers, and the diameters of fibers are mostly in the range of 100~200 nm. The porosity and BET specific surface area of aluminum silicate nanofibers separator with 150 μm thickness are 56.1% and 113.5 m2/g, greater than that of commercial PP separator. When tested in supercapacitors, their ionic conductivity and ion diffusion resistance are 0.041 S/cm and 1.09 Ω, better than that of the commercial PP separator (0.029 S/cm and 2.74 Ω). The specific capacitance of supercapacitors prepared with aluminum silicate nanofibers of 150-μm thickness as separator is up to 150 F/g, which is higher than that of the commercial PP separator (65 F/g). The cyclic and rate performances of supercapacitors prepared with aluminum silicate nanofibers separator are also improved significantly. Compared with commercial PP separator, the aluminum silicate nanofibers separator shows outstanding thermal stability and flame resistance. Hence, the obtained aluminum silicate nanofibers separator has good practical application prospect in supercapacitor.

A superflexible hydrophobic silica-based aerogel (FHSA) was prepared via a facile sol-gel process and ambient pressure drying method. The FHSA was treated at different temperatures varying from -196 to 450 °C to evaluate its thermal and mechanical performances. The evolutions of the physical property, hydrophobicity, microstructure, pore structure, and chemical structure of the FHSA with the various treatment temperatures were investigated comprehensively. The structure of the FHSA did not show an obvious change after treatment in the liquid nitrogen. The bulk density of the FHSA increased from 0.047 to 0.077 g cm-3 when the thermal treatment temperature increased from 25 to 450 °C. The specific surface area and pore volume of the FHSA increased with the treatment temperature owing to the decomposition of the organic moieties. The Fourier transform infrared spectra showed that the methyl groups in the FHSA had excellent thermostability up to 400 °C. The water contact angles of the FHSA after treatment at -196, 25, 200, 300, 350, 400, and 450 °C were 131, 151, 162, 150, 132, 119, and 34°, respectively. The thermal conductivity of the FHSA at a low temperature of -10 °C was 0.022 W m-1 K-1. The reversible deformation rate of the FHSA was more than 80% within 100 compression cycles. After treatment in liquid nitrogen, the reversible deformation rate of the FHSA remained at 50%. The synthesis method of the FHSA is simple, the resulting FHSA showed good performance both in thermostability and flexibility, and it is promisingly applied for thermal insulation and sealing in ultralow-temperature environments.

A new material of Ag-SnO2/rGO aerogel is fabricated by the sol-gel method and freeze-drying technique. The SnO2 particles are tightly arranged on the rGO sheets to form a p-n heterojunction, and the rGO aerogel possesses abundant pore structures for effective adsorption. Besides, the Ag particles are dispersed on the surface as a catalyst to improve the internal electron mobility, further promoting the gas-sensing performance. To be noted, the Ag-SnO2/rGO aerogel can exhibit a response of 2.13 towards 50 ppm NO2 at RT instead of heating conditions, and shows a cyclic capacitance property of redox. Moreover, the non-linear growth between gas concentration and response is observed, which proves the chemical adsorption that results in the high selectivity.

The aim of this paper is to study the differences of the aggregation structure, physical properties and chemical composition of different parts of ramie fiber, as well as segmented degumming processes applying to those different parts. The ramie was divided into three parts, namely the root, the middle and the head and then the traditional two-step alkali method was adopted for degumming. It has been observed that the linear density and breaking strength reduced gradually from the root to head and the friction coefficient of the head was the largest. X-ray diffraction measurement found that the crystallinity of the middle fiber was the highest. Fourier transform infrared spectroscopy revealed that the component content of different parts was not the same and there was much more gum content on the head, which was also confirmed by scanning electron microscopy. To shorten the degumming process and reduce the energy consumption that the two-step segmented degumming caused, the one-step optimization process was explored. The results illustrated that by using one-step optimization segmented degumming, the residual gum content of the head, the middle and the root were 2.55%, 2.17% and 2.12%, respectively. By using two-step degumming, the residual gum contents were 2.16%, 1.97% and 2.07%, respectively. Contrasting one-step degumming and two-step degumming, it could be concluded that the head and the middle parts were suitable for two-step degumming while the root part was suitable for one-step degumming.

The aim of this paper is to study the hygroscopic behavior of hygroscopic exothermic fiber-based materials and to obtain a better understanding of the thermal performance of these fibers during the moisture absorption process. The temperature distribution of different kinds of hygroscopic exothermic fibers in the process of moisture absorption, observed by infrared camera, demonstrated two types of heating performance of these fibers, which might be related to its hygroscopic behavior. Based on the sorption isotherms, a Guggenheim-Anderson-de Boer (GAB) multi-layer adsorption model was selected as the optimal moisture absorption fitting model to describe the moisture absorption process of these fibers, which illustrated that water sorption capacity and the water&ndash, fiber/water&ndash, water interaction had a significant influence on its heating performance. The net isosteric heats of sorption decreased with an increase of moisture content, which further explained the main factor affecting the heat dissipation of fibers under different moisture contents. The state of adsorbed water and water vapor interaction on the fiber surface were studied by simultaneous thermal analysis (TGA-DSC) measurement. The percentage of bound and unbound water formation at low and high humidity had a profound effect on the thermal performance of fibers. It can therefore be concluded that the content of tightly bound water a strong water&ndash, fiber interaction was the main factor affecting the heating performance of fibers at low moisture content, and the content of loosely bound water reflected that water sorption capacity was the main factor affecting the heating performance of fibers at high moisture content. This was further proven by the heat of desorption.

The setaria viridis-like TiN fibers with efficient electromagnetic wave absorption in the whole X and Ku bands were prepared by electrospinning and hydrothermal methods. The results of XRD, Raman, and XPS suggested the presence of cubic TiN phase with TiOxNy solid solution form in fibers. The nanoneedles uniformly grew on the fibers’ surfaces along the (2 0 0) plane of cubic TiN crystal and formed a setaria viridis-like morphology. The bionic hierarchical structure gave rise to a large number of interfaces and pores, which would provide the suitable impedance matching, multiple reflections and scatterings, conductivity loss, and Debye relaxation through the synergistic effect. Hence, the superior absorption properties were achieved in the whole X and Ku bands by adjusting the fibers’ filler loading. The optimal reflection loss could reach −45.8 dB (X-band) at a thickness of 1.38 mm and −47.8 dB (Ku-band) at the thickness of 1.11 mm as the fibers absorbent contents were 20 wt% and 15 wt%, respectively. Furthermore, the effective absorption bandwidth covered the entire X and Ku bands with a thin thickness of 1.0–2.0 mm.

Si3N4 aerogel, which is one of the most promising materials for application as high-temperature thermal insulation, is synthesized by the urea-assisted sol-gel technique, followed by the supercritical drying, carbonization, carbothermal reduction and carbon combustion processes. The effects of heat treatment temperatures on the physicochemical and textural evolution of mesoporous Si3N4 aerogel are investigated. Si3N4 aerogel is formed when the heat treatment temperature increases to 1500 °C, whereas it transforms into SiC phase with a further higher temperature of 1600 °C. The SEM analysis confirms the existence of Si3N4 nanoparticles, and the particle size of Si3N4 nanoparticles is around 20–40 nm, with pore size around 20–40 nm. The XPS measurement reveals that Si3N4 aerogel is composed of 74.4% Si3N4 phase, with lower content of 25.6% SiO2. Si3N4 aerogel possesses a large BET specific surface area of 519.6 m2/g, which results from the mesoporous pores left after carbon combustion. This value is much larger than that of the conventional Si3N4 porous ceramics and Si3N4 nano materials ever reported. The BJH adsorption average pore diameter of Si3N4 aerogel is around 11.8 nm, with a large pore volume of 3.5 cm3/g. Si3N4 oxidation with forming amorphous SiO2 layer on the surface is observed by the TG measurement. Moreover, the resulting Si3N4 aerogel shows low bulk density of 0.075 g/cm3, as well as low thermal conductivity of 0.045 W/(m·K) at room temperature. The mechanism of Si3N4 formation is based on the VS growth between C, SiO2 and N2. The structures evolution and formation mechanism of Si3N4 aerogel are also investigated in this study.

A plasmonic waveguide system composed of metal-insulator-metal (MIM) stub coupled with circular cavity resonator was proposed to produce ultra sharp Fano resonances, which resulted from the coupling between the ultra narrow discrete resonances and the ultra broad spectrum of the plasmonic circular cavity and stub resonator, respectively. The spectral line shapes of the Fano resonances can be easily adjusted by changing the structure parameters. And the transmittance of the system can sharply decrease from peak (“on state”) to valley (“off state”) with wavelength shifts of only about 8 nm. Due to the sharp phase change of the ultra asymmetric Fano resonance, a maximum group index of about 180 can be realized. Also, the ultra sharp spectrum contributes to a highly efficient plasmonic refractive index sensor, which can yield a linear sensitivity of 1277 nm/RIU and figure of merit of about 2.1 × 104. The proposed structure may have potential applications in nanoscale filter, slow light, and refractive index sensor.

A low cost polymer sampled waveguide Bragg grating which can be fabricated by using the simple contact lithography is proposed. By using the contact lithography and reactive ion etching, the sampled Bragg grating structures were fabricated on the waveguide bottom cladding, where a channel waveguide was fabricated on top of it as the waveguide core to form the polymer sampled waveguide Bragg grating working at around 1550 nm. The measured transmission and reflection spectra of the fabricated polymer sampled waveguide Bragg grating exhibit multiple dips and peaks, respectively. And the wavelength interval among the peaks is 0.376 nm, which shows good agreement with the theoretical predictions.

Although the power conversion efficiency (pce) of small-area polymer solar cells (pscs) has now surpassed 10% upon various optimizations, it is still a challenge to improve the performance of large-area device partially due to the problems encountered in film morphology optimization and incompatibility of using these optimizations for size scale-up. herein, we reported a method to effectively improve the morphology of photoactive layer and thus device efficiency under ambient atmosphere by using spray coating technique. it was found that by finely adjusting the parameters of the instrument, and the properties of the "electronic ink'', the dynamics of solvent evaporation after film deposition could be controlled. by resorting to a few techniques for morphology characterization, it confirmed that the resulting blend film showed desirable vertical phase separation where polymer enriched near the anode and pcbm adjacent to the cathode. the graded composition is beneficial for the efficient charge transportation as well as eventual charge collection. by using pbdt-tfq/pc71bm composite as an example, the exceptional high pces of 4.6% and 4.1% were achieved for the devices with the size of 1.0 and 10.2 cm(2), respectively. in comparison to conventional device fabrication process, this method is not only simple without additional treatment steps, but also dramatically increases the device efficiency, which opens a new way for fabricating highly efficient large-area pscs. (c) 2015 elsevier b.v. all rights reserved.

Waveguide ring resonators (WRRs) operating at a telecom window of 1.4∼1.6 μm based on asymmetric Au-(Pb, La)(Zr, Ti)O3-Au structure is proposed and investigated. Electro-optical control of such WRRs is conducted by introducing epitaxial (Pb, La)(Zr, Ti)O3 (PLZT) thin films as the core layer deposited between the upper and lower gold slabs with different widths. The long-term reliability, large electro-optic (EO) coefficients, and spontaneous polarization properties of PLZT thin films have ensured high performance of our WRRs. It has been demonstrated that the footprint of WRR can be fabricated less than 20 μm2 with the radius of ring resonator around 1 μm through combining PLZT thin films with surface plasmons (SPs). Furthermore, the large extinction ratio (∼43 dB), as well as comparatively low insertion loss (

In-situ carbon-thermal reduction of cobalt oxide nanoparticles supported on carbon nanotubes was studied by cobalt 2p3d resonant inelastic X-ray scattering (RIXS). The in-situ 2p X-ray absorption spectroscopy (XAS) and RIXS measurements were performed at 500, 600, and 700 °C, where four consistent excitation energies were used for RIXS acquisitions. After 700 °C reduction, the XAS spectrum shows a cobalt metal-like shape, while the RIXS spectra reveal the minority cobalt monoxide phase. The holistic fit on both XAS and RIXS data reveals the respective contributions from metal and monoxide. We show that the relative precision to determine the monoxide content changes from ∼5.6% in XAS results to better than 0.8% in the RIXS analysis, suggesting that RIXS is a useful tool to track the oxidation state of nanoparticles under in situ conditions. We determined a relative radiative ratio (P) factor of approximately 5, where this factor gives the ratio between the relative strengths of the radiative decay channels compared to the nonradiative channels in CoO and Co metal.

This paper proposes a green energy-saving maintenance room.The maintenance room can solve most of the problems faced by most cement product curing rooms during use. For example, poor insulation performance and low level of automation.according to the specific requirements of the maintenance of room temperature and humidity, a cement room temperature and humidity control system was designed to detect and control the temperature, humidity and other parameters of the cement product curing room. The temperature field during the operation of the green energy-saving room through ANSYS was analyzed. The results showed that the optimum temperature of solar hot air blowing in the curing room was 70°C.

By means of the transfer-matrix method, the effects of parameter modulation on the quality of near-field imaging in one-dimensional photonic crystal consisting of alternately left-handed material and right-handed material are investigated. Based on analyses of the recovery rate and phase shift, the results show that the imaging quality is not obviously affected by the minor changes of layer thickness. In addition, by modulating the material parameters of the left-handed material, it is found that for both the real part and the imaginary part, the system is more sensitive to the permeability than the permittivity for the TE wave. For the TM wave, it is reverse. These properties are very useful to fabricate left-handed material photonic crystals in practice.

We fabricate the hybrid films of colloidal CdSe/ZnS quantum dots (QDs) and poly(9-vinylcarbazole) (PVK) sandwiched between two electrodes. The voltage and temperature dependences of the electroluminescence (EL) are measured. The quantum-confined Stark effect of colloidal QDs is clearly observed. To explore the mechanism in the QD EL, hybrid films are fabricated with different concentrations of colloidal QDs. Electrons and holes are proposed to be separately transported in QDs and PVK, respectively.

We synthesize colloidal CdSe/CdS core/shell quantum dots with different shell thicknesses, and there are five samples including CdSe core dots, and CdSe/CdS core/shell dots with 1–4 CdS layers. X-ray diffraction and Raman measurements indicate that the stress in CdSe core becomes stronger with the increasing shell thickness, and the optical measurements show that when the shell becomes thicker, the photoluminescence quantum yield is enhanced, and the radiative decay is also expedited. The temperature-dependent optical spectra are measured. The relation between the microstructure and the optical properties is discussed.

We present the results of point-contact spectroscopy measurements on high-quality epitaxial MgB2 thin films with injected current along the c-axis. The temperature and field dependences of π-band properties with the field parallel to (H||) or perpendicular to (H⊥) the c-axis are investigated in detail. When a magnetic field is applied, either parallel or perpendicular to the c-axis, the density of the quasiparticle state (DOS) of the π-band proliferates quickly with increasing field, while the gap amplitude of the π-band decreases slowly, which is different from the recent theoretical calculations, showing a field dependent competition between the interband scattering and the pair-breaking effects.

Single-negative materials based on photonic crystal with multiple defect layers are designed and the free modulation of defect modes is studied. The results show that the multi-defect structure can avoid the interference between the defect states. Therefore, the designed double defect modes in the zero effective-phase gap can be adjusted independently by changing the thickness of different defect layers. In addition, the two tunable defect modes have the omnidirectional characteristics. This multi-defect structure with above-mentioned two advantages has potential applications in modern optical devices such as tunable omnidirectional filters.

A newly synthesized 1,3,4-oxadiazole derivatives have been studied using a femtosecond Ti:sapphire laser system. The series molecules present strong three-photon absorption and frequency upconversion fluorescence at wavelengths from 1205nm to 1575nm. Furthermore, there is no proportional relationship between three-photon absorption cross sections and the chemical structure transformation from monomer, dimer to trimer. Effective charge-transfer distance by π-conjugation bonds may be the contributing factor. In the experimental design, the far-field intensity distribution of femtosecond laser beam has been taken into account. We give the optimized analytical solution of nonlinear transmission in a three-photon absorption (3PA) process when the incident beam has a Gaussian transverse spatial profile.

Nanocombs with a disc cap structure of ZnO have been synthesized on Si substrates by using pure Zinc powders as the source materials based on a vapour-phase transport process. The morphology and the microstructure are investigated by a scanning electron microscopy and x-ray diffraction. Based on the transmission electron microscopy and selected area electron diffraction analysis, the growth directions of three representative parts, nanoribbon stem, nanorod branch and nanodisc cap of the nanocomb are revealed. The growth mechanism of the disc-capped nanocombs is discussed based on the self-catalyzed vapour-liquid-solid process.

Surface-enhanced Raman scattering (SERS) is a powerful and non-destructive analytical technique tool for chemical and biological sensing applications. Metal-free SERS substrates have recently been developed by using semiconductor nanostructures. The optical property of TiN film is similar to that of gold. Besides that, its good chemical inertness and thermodynamic stability make TiN thin film an excellent candidate for SERS. In order to investigate its SERS activity, the TiN thin film was successfully prepared via direct nitridation of the sol-gel derived TiO 2 thin film on the quartz substrate using ammonia gas as reducing agent. The crystallite structures and morphology of TiN thin film were determined by XRD, RAMAN and FE-SEM. The results show that the thin film obtained is cubic titanium nitride with a lattice parameter of 4.2349 A. The surface of TiN thin film is rough and with the particles of 50 nm in average sizes. The thickness of TiN thin film is about 130 nm. The TiN thin film displays a surface Plasmon resonance absorption peak at around 476 nm, which can lead to a strong enhancement of the EM field on the interface. The Raman signal of the probe molecule R6G was greatly enhanced through TiN thin film substrates. The enhancement factor is about 4.1×10 3 and the detection limit achieves 10 -6 M for R6G. The TiN thin film substrate also shows a good reproducibility of SERS performance. The results indicate that TiN thin film is an attractive material with potential application in SERS substrates.

A modulation frequency multiplexed dual diode-laser system is developed for simultaneous detection of the two most common fire gas products CO and CO2. Simultaneous detection is achieved by modulating each laser at different frequencies, demodulating the signal by a pair of lock-in amplifiers for each gas. Laser beams are combined and detected by one detector after passing through an identical optical path. The experimental results show little performance degradation associated with modulation frequency multiplexing, and no cross-talk between the two multiplexed detection channels is measured.

The behaviour of a high efficient double-pass discrete Raman amplifier with 80nm bandwidth was studied theoretically and experimentally. In this Raman amplifier, by using a one-end gilt fibre as the broadband reflector, signals and multi-pump are simultaneously reflected to propagate through the gain fibre for a second time in the opposite direction of the input. An increase in net gain of more than 150% has been achieved compared with that in the typical co-pumped Raman amplifier. The advantages of this new configuration have been studied by comparing with the currently existing Raman amplifier configurations. Also, the influencing factors for the gain increase have been analysed, including the pump-to-pump Raman interactions and the length of gain fibre.

One-dimensional photonic crystals with two or more structural defects are studied. We observed an interesting characteristic of transmission band structure of photonic crystals with defects using the transmission-matrix-method simulation. The transmission states in the wide photonic band gap caused by defects reveal degeneracy and split in certain conditions. Every split state is contributed by coupling of all defects in a photonic crystal. Using the tight-binding method, we obtain an approximate analytic expression for the split frequency of photonic crystals with two structural defects.

One effective method for suppression of coupling from guided optical modes into cladding modes in an optical fibre Bragg grating is to use cladding mode suppression fibre. In this specially engineered fibre, the grating is written into the core and the inner cladding, both of which are photosensitive. A theory is presented in this paper to analyse the spectral characteristics of this kind of gratings. A fibre Bragg grating was experimentally fabricated with this kind of photosensitive fibre (PS-RMS-50 from StockerYale). It is shown both theoretically and experimentally that such gratings exhibit strong suppression of the coupling between core mode and cladding mode. The experimental result is in good agreement with the theoretical analysis.

High vacuum is required for Vacuum Pressure Impregnation (VPI) process of large coils used in cryogenic. The defects such as dry spots and over rich resins should be minimized in large superconducting coils used. Both sealing problems associated with the mold and over rich resin problems are eliminated by using vacuum bag mold method with which we can simplify the design of vacuum mold.

Monte Carlo simulation is performed to study the adsorption properties of polymers on an attractive surface. Annealing method is adopted to simulate the adsorption characteristics and conformational changes of polymer chains driven by an external driving force F. In simulations using cooperative motion algorithm, the ensembles of monomers located at lattice sites are connected by non-breakable bonds. When the external force is F=0, the finite-size scale method can be used to determine the critical adsorption temperature (Tc) of the polymer chain on the attractive surface, but when the external force is F>0, the dependence of the average number of surface contacts M> on the chain length N is unrelated to temperature T. Therefore, Tc cannot be obtained by the finite-size scale method. However, the pseudo-critical adsorption temperature Tc can be estimated by a function of the average number of surface contacts M> and the temperature T for the chain length N=200. And then Tc decreases with external force F increasing. The phase diagram is obtained for the polymer chain between the desorbed state and the adsorbed state under temperature T and external driving force F. Furthermore, the influence of the external driving force on the conformation of the polymer chain is analyzed by the mean square radius of gyration of polymer chains. The critical adsorption point Tc can be checked roughly by the minimum location of the mean square radius of gyration or by the variation of its components in the Y and Z direction perpendicular to the external force. With the increase of the external force F for adsorbed polymer, the temperature T can determine whether polymer is changed from the adsorption state to the desorption state and where the force is located at the transformation. There are two different cases, that is, the polymer can be desorbed at the temperature Tc* TTc and the polymer cannot be desorbed at T Tc*. In this paper, we discuss these two cases for the adsorption of polymer on the attractive surface:weak and strong adsorption. In the first case, the adsorption is strongly influenced by the external driving force. By contrast, in the strong adsorption, the adsorption is weakly influenced by the external force. Our results unravel the dependence of adsorption of polymer on external driving force, which is also consistent with the phase diagram of adsorption and desorption of polymer chains.

The HT-7U superconducting tokamak is a full-superconducting magnetically confined fusion device, The toroidal magnet system of HT-7U is a very important part of the device. In VPI (Vacuum-Pressure Impregnation) process the magnet coils must be heated and degassed before impregnating and must be heated to the gel temperature and then the curing temperature, and keep the two kinds of temperatures for a long period of time after impregnating. Thus the heating method of VPI is critical. In this paper, a hybrid method of combining the internal and external heating for the coils is analyzed, especially the possibility of the internal heating method is proved.

Tris (8-hydroxyquinoline) aluminium (Alq3) nano-structured films are fabricated by the gas evaporation method, and their fluorescent properties are investigated in detail. Compared with the conventional amorphous Alq3 films, the fluorescent efficiency of the nanostructure films is enhanced to a certain extent.

An all-thin-film (ATF) electrochromic device for modulating the optical transmittance is manufactured using magnetron sputtering. The devices consists of MoO3 as the main electrochromic layer, LiBO2+Li2SO4(LiBSO) as the ion conductor layer, and NiOx as the complementary electrochromic layer. Glass covered with indium tin oxide (ITO) is used as the substrate and the ITO film is used as the bottom electrode. The ITO film deposited o the top of the devices is used as the other electrode. The structure and morphology of the films are characterize by x-ray diffraction (XRD) and scanning electron microscopy (SEM). The devices exhibit good optical properties with low transmittance values in the coloured state, and the optical modulation is measured by spectrophotometer in the wavelength range from 400 to 800 nm. The average visible light transmittance reaches 50.2% and 3.7% i bleached and coloured state, respectively. The results indicate that such a monolithic system has great potential to be applied in smart windows.

A symmetrical π-shaped metamaterial is investigated. Numerical simulations exhibit the negative-refractive property of this structure. The complex refractive index n, wave impedance z, effective permittivity and effective permeability μ have been retrieved from the simulated S parameters. The negative-refractive band lies between 11.2GHz and 13.05GHz. The frequency band with high transmission with low loss occurs between 11.95GHz and 12.5 GHz, which is helpful for practical applications. The mechanism of the electromagnetic resonance is also revealed.

Employing an organic dye salt of trans-4-[p-[N-methyl-N-(hydroxymethyl)amino]styryl]-N-methylphridinium tetraphenylborate (ASPT) as the active layer, 8-hydrocyquinoline aluminium (Alq3) as the electron transporting layer and N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine (TPD) as the hole transporting layer, respectively, we fabricate a multi-layered organic light-emitting diode and observe the colour tunable electroluminescence (EL). The dependence of the EL spectra on the applied voltage is investigated in detail, and the recombination mechanism is discussed by considering the variation of the hole-electron recombination region.