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Fabricating heterojunctions with precisely controlled interfacial structures is crucial for exploring novel low-dimensional physics and for realizing high-performance devices. However, such capabilities are often constrained by contamination from the ambient environment or by the limitations of applicable methods and materials under vacuum conditions. In this study, MoS2/Au(111) heterostructures were fabricated by exfoliating MoS2 thin layers onto a crystallized Au(111) surface using a gold-assisted exfoliation method in an ultra-high vacuum environment. This method yields millimeter-sized monolayer or sub-millimeter-sized bilayers with contamination-free interfaces, which are unattainable for samples made in air. Scanning tunneling microscopy revealed that both the monolayer and the bilayer exhibit uniform and well-ordered moiré superlattices controlled by the twisting angle between the Au(111) surface and the MoS2 overlayer. The direct contact with the Au surface renders the monolayer MoS2 weakly metallic, while a less coupled bilayer is semiconducting, indicating a 0.54 eV Schottky barrier for the MoS2/Au(111) contact. This method is applicable to various combinations of van der Waals materials and metal surfaces. The uniform and controllable heterojunctions can serve as ideal model systems for exploring semiconductor–metal interfaces and atomic structures formed within.

Abstract Neural circuits with specific structures and diverse neuronal firing features are the foundation for supporting intelligent tasks in biology and are regarded as the driver for catalyzing next-generation artificial intelligence. Emulating neural circuits in hardware underpins engineering highly efficient neuromorphic chips, however, implementing a firing features-driven functional neural circuit is still an open question. In this work, inspired by avoidance neural circuits of crickets, we construct a spiking feature-driven sensorimotor control neural circuit consisting of three memristive Hodgkin-Huxley neurons. The ascending neurons exhibit mixed tonic spiking and bursting features, which are used for encoding sensing input. Additionally, we innovatively introduce a selective communication scheme in biology to decode mixed firing features using two descending neurons. We proceed to integrate such a neural circuit with a robot for avoidance control and achieve lower latency than conventional platforms. These results provide a foundation for implementing real brain-like systems driven by firing features with memristive neurons and put constructing high-order intelligent machines on the agenda.

Abstract Flexible and miniaturized photodetectors, offering a fast response across the ultraviolet (UV) to millimeter (MM) wave spectrum, are crucial for applications like healthcare monitoring and wearable optoelectronics. Despite their potential, developing such photodetectors faces challenges due to the lack of suitable materials and operational mechanisms. Here, the study proposes a flexible photodetector composed of a monolayer graphene connected by two distinct metal electrodes. Through the photothermoelectric effect, these asymmetric electrodes induce electron flow within the graphene channel upon electromagnetic wave illumination, resulting in a compact device with ultra‐broadband and rapid photoresponse. The devices, with footprints ranging from 3 × 20 µm2 to 50 × 20 µm2, operate across a spectrum from 325 nm (UV) to 1.19 mm (MM) wave. They demonstrate a responsivity (RV) of up to 396.4 ± 5.1 mV W−1, a noise‐equivalent power (NEP) of 8.6 ± 0.1 nW Hz−0.5, and a response time as small as 0.8 ± 0.1 ms. This device facilitates direct imaging of shielded objects and material differentiation under simulated human body‐wearing conditions. The straightforward device architecture, aligned with its ultra‐broadband operational frequency range, is anticipated to hold significant implications for the development of miniaturized, wearable, and portable photodetectors.

Abstract One of the main bottlenecks in the development of terahertz (THz) and long-wave infrared (LWIR) technologies is the limited intrinsic response of traditional materials. Hyperbolic phonon polaritons (HPhPs) of van der Waals semiconductors couple strongly with THz and LWIR radiation. However, the mismatch of photon − polariton momentum makes far-field excitation of HPhPs challenging. Here, we propose an In-Plane Hyperbolic Polariton Tuner that is based on patterning van der Waals semiconductors, here α-MoO3, into ribbon arrays. We demonstrate that such tuners respond directly to far-field excitation and give rise to LWIR and THz resonances with high quality factors up to 300, which are strongly dependent on in-plane hyperbolic polariton of the patterned α-MoO3. We further show that with this tuner, intensity regulation of reflected and transmitted electromagnetic waves, as well as their wavelength and polarization selection can be achieved. Our results can help the development of THz and LWIR miniaturized devices.

Two-dimensional layered materials, characterized by their atomically thin thicknesses and surfaces that are free of dangling bonds, hold great promise for fabricating ultrathin, lightweight, and flexible bipolar junction transistors (BJTs). In this paper, a van der Waals (vdW) BJT was fabricated by vertically stacking MoS2, WSe2, and MoS2 flakes in sequence. The AC characteristics of the vdW BJT were studied for the first time, in which a maximum common emitter voltage gain of around 3.5 was observed. By investigating the time domain characteristics of the device under various operating frequencies, the frequency response of the device was summarized, which experimentally proved that the MoS2/WSe2/MoS2 BJT has voltage amplification capability in the 0–200 Hz region. In addition, the phase response of the device was also investigated. A phase inversion was observed in the low-frequency range. As the operating frequency increases, the relative phase between the input and output signals gradually shifts until it is in phase at frequencies exceeding 2.3 kHz. This work demonstrates the signal amplification applications of the vdW BJTs for neuromorphic computing and wearable healthcare devices.

Two-dimensional (2D) materials have attracted great attention in the past few years and offer new opportunities for the development of high-performance and multifunctional bipolar junction transistors (BJTs). Here, a van der Waals BJT based on vertically stacked n+-MoS2/WSe2/MoS2 was demonstrated. The electrical performance of the device was investigated under common-base and common-emitter configurations, which show relatively large current gains of α ≈ 0.98 and β ≈ 225. In addition, the breakdown characteristics of the vertically stacked n+-MoS2/WSe2/MoS2 BJT were investigated. An open-emitter base-collector breakdown voltage (BVCBO) of 52.9 V and an open-base collector-emitter breakdown voltage (BVCEO) of 40.3 V were observed under a room-temperature condition. With the increase in the operating temperature, both BVCBO and BVCEO increased. This study demonstrates a promising way to obtain 2D-material-based BJT with high current gains and provides a deep insight into the breakdown characteristics of the device, which may promote the applications of van der Waals BJTs in the fields of integrated circuits.

Exploring novel nanotechnology schemes for tunable broadband vacuum photodetection devices is of great significance. Herein, a strategy to combine a field‐emission cold cathode with plasmonic nanostructures to form a plasmon‐enhanced field‐emission metasurface array is proposed. Mo nanostructures with excellent emission properties act as field‐emission cold cathode materials. Au nanospheres are applied to enhance the photocurrent of Mo nanopyramid emitters and to generate tunable resonance responses by plasmonic couplings. The response frequency and polarization can be selective in a broadband range from visible to near‐infrared, which originates from the periodic couplings of the Mo–Mo microcavities and the Au–Mo interfaces in the designed metasurface emitter arrays. The amplitude of photodetection signals is experimentally demonstrated to be tunable not only by the geometrical dimensions of the Mo nanopyramid and the number of decorated Au plasmons, but also by the applied external electrostatic fields. This plasmon‐enhanced photoresponse field‐emission process is attributed to plasmon‐mediated electron emission. Herein, a route to tunable broadband photoresponse electron‐emission nanostructures at room temperature (≈300 K) and low energy consumption for photocathode and vacuum device applications is provided in the results.

Abstract Polar van der Waals (vdW) crystals that support phonon polaritons have recently attracted much attention because they can confine infrared and terahertz (THz) light to deeply subwavelength dimensions, allowing for the guiding and manipulation of light at the nanoscale. The practical applications of these crystals in devices rely strongly on deterministic engineering of their spatially localized electromagnetic field distributions, which has remained challenging. The polariton interference can be enhanced and tailored by patterning the vdW crystal α‐MoO3 into microstructures that support highly in‐plane anisotropic phonon polaritons. The orientation of the polaritonic in‐plane isofrequency curve relative to the microstructure edges is a critical parameter governing the polariton interference, rendering the configuration of infrared electromagnetic field localizations by enabling the tuning of the microstructure size and shape and the excitation frequency. Thus, the study presents an effective rationale for engineering infrared light flow in planar photonic devices.

Abstract Nanowire field emitters have great potential for use as large-area gated field emitter arrays (FEAs). However, the micrometer-scale cathode patterns in gated FEA devices will reduce regulation of the gate voltage and limit the field emission currents of these devices as a result of field-screening effect among the neighboring nanowires. In this article, a ring-shaped ZnO nanowire pad is proposed to overcome this problem. Diode measurements show that the prepared ring-shaped ZnO nanowire pad arrays shows uniform emission with a turn-on field of 5.9 V/µm and a field emission current density of 4.6 mA/cm2 under an applied field of 9 V/µm. The ZnO nanowire pad arrays were integrated into coplanar-gate FEAs and enhanced gate-controlled device characteristics were obtained. The gate-controlled capability was studied via microscopic in-situ measurements of the field emission from the ZnO nanowires in the coplanar-gate FEAs. Based on the results of both simulations and experiments, we attributed the enhanced gate-controlled device capabilities to more efficient emission of electrons from the ZnO nanowires as a result of the increase edge area by designing ring-shaped ZnO nanowire pad. The results are important to the realization of large-area gate-controlled FEAs based on nanowire emitters for use in vacuum electronic devices.

Abstract Transition-metal dichalcogenide (TMD) semiconductors have attracted interest as photoelectrochemical (PEC) electrodes due to their novel band-gap structures, optoelectronic properties, and photocatalytic activities. However, the photo-harvesting efficiency still requires improvement. In this study, A TMD stacked heterojunction structure was adopted to further enhance the performance of the PEC cathode. A P-type WSe2 and an N-type MoS2 monolayer were stacked layer-by-layer to build a ultrathin vertical heterojunction using a micro-fabrication method. In situ measurement was employed to characterize the intrinsic PEC performance on a single-sheet heterostructure. Benefitting from its built-in electric field and type II band alignment, the MoS2/WSe2 bilayer heterojunction exhibited exceptional photocatalytic activity and a high incident photo-to-current conversion efficiency (IPCE). Comparing with the monolayer WSe2 cathode, the PEC current and the IPCE of the bilayer heterojunction increased by a factor of 5.6 and enhanced 50%, respectively. The intriguing performance renders the MoS2/WSe2 heterojunction attractive for application in high-performance PEC water splitting.

A cold cathode has many applications in high frequency and high power electronic devices, X-ray source, vacuum microelectronic devices and vacuum nanoelectronic devices. After decades of exploration on the cold cathode materials, ZnO nanowire has been regarded as one of the most promising candidates, in particular for large area field emitter arrays (FEAs). Numerous works on the fundamental field emission properties of ZnO nanowire, as well as demonstrations of varieties of large area vacuum microelectronic applications, have been reported. Moreover, techniques such as modifying the geometrical structure, surface decoration and element doping were also proposed for optimizing the field emissions. This paper aims to provide a comprehensive review on recent progress on the ZnO nanowire cold cathode and its applications. We will begin with a brief introduction on the synthesis methods and discuss their advantages/disadvantages for cold cathode applications. After that, the field emission properties, mechanism and optimization will be introduced in detail. Then, the development for applications of large-area ZnO nanowire FEAs will also be covered. Finally, some future perspectives are provided.

Understanding the effect of grain boundaries on the electrical and thermal transport properties of graphene is of both fundamental and technological importance. Here, the authors fabricate graphene films with controlled grain size, and determine the scaling laws of thermal and electrical conductivities.

China is the world’s leading country for potato production but potato is not native to China. To gain insights into the genetic diversity of potato germplasm various studies have been performed but no study has been reported for potato landraces in China. To improve the available genepool for future potato breeding programs, a diverse population containing 292 genotypes (including foreign elite lines, local landraces and cultivars) was developed and genotyped using 30 SSR markers covering the entire potato genome. A total of 174 alleles were detected with an average of 5.5 alleles per locus. The model-based structure analysis discriminated the population into two main sub-groups, which can be further subdivided into seven groups based on collection sites. One sub-group (P1) revealed less genetic diversity than other (P2) and contained a higher number of commercial cultivars possibly indicating a slight reduction in diversity due to selection in breeding programs. The P2 sub-group showed a wider range of genetic diversity with more new and unique alleles attained from wild relatives. The potato landraces, clustered in sub-population P1 may be derived from historical population imported from ancient European and International Potato Center genotypes while sub-population P2 may be derived from modern populations from International Potato Center and European genotypes. It is proposed that in the first step, the potato genotypes were introduced from Europe to China, domesticated as landraces, and then hybridized for modern cultivars.

This paper investigates the observability of first-order, second-order, and high-order leader-based multiagent systems (MASs) with fixed topology, respectively. Some new algebraic and graphical characterizations of the observability for the first-order MASs are established based on agreement protocols. Moreover, under the same leader-following framework with the predefined topology and leader assignment, the observability conditions for systems of double-integrator and high-integrator agents are also obtained. Finally, the effectiveness of the theoretical results is verified by numerical examples and simulations.

The excellent properties of silicon carbide (SiC) make it widely applied in high-voltage, high-power, and high-temperature electronic devices. SiC nanowires combine the excellent physical properties of SiC material and the advantages of nanoscale structures, thus attracting significant attention from researchers. Herein, the electron vacuum tunneling emission characteristics of an individual SiC nanowire affected by the piezoresistive effect are investigated using in situ electric measurement in a scanning electron microscope (SEM) chamber. The results demonstrate that the piezoresistive effect caused by the electrostatic force has a significant impact on the electronic transport properties of the nanowire, and the excellent electron emission characteristics can be achieved in the pulse voltage driving mode, including lower turn-on voltage and higher maximum current. Furthermore, a physical model about the piezoresistive effect of SiC nanowire is proposed to explain the transformation of electronic transport under the action of electrostatic force in DC voltage and pulsed voltage driving modes. The findings can provide a way to obtain excellent electron emission characteristics from SiC nanowires.

Plasmonic gold nanorods play important roles in nowadays state-of-the-art plasmonic sensing techniques. Most of the previous studies and applications focused on gold nanorods with relatively small aspect ratios, where the plasmon wavelengths are smaller than 900 nm. Gold nanorods with large aspect ratios are predicted to exhibit high refractive-index sensitivity (Langmir 2008, 24, 5233–5237), which therefore should be promising for the development of high-performance plasmonic chemical- and bio-sensors. In this study, we developed gold nanorods with aspect ratios over 7.9, which exhibit plasmon resonances around 1064 nm. The refractive index (RI) sensitivity of these nanorods have been evaluated by varying their dielectric environment, whereby a sensitivity as high as 473 nm/RIU (refractive index unit) can be obtained. Furthermore, we have demonstrated the large-aspect-ratio nanorods as efficient substrate for surface enhanced Raman spectroscopy (SERS), where an enhancement factor (EF) as high as 9.47 × 108 was measured using 4-methylbenzenethiol (4-MBT) as probe molecule. Finally, a type of flexible SERS substrate is developed by conjugating the gold nanorods with the polystyrene (PS) polymer. The results obtained in our study can benefit the development of plasmonic sensing techniques utilized in the near-infrared spectral region.

The temperature dependence of the field emission properties of CuO nanowires was studied from 163 to 453 K. Large current increases were observed with increasing temperature, which cannot be explained by band to band excitation or emission from the valence band. Two distinct sections were observed from the Arrhenius plot. Activation energies of 100 meV for the high-temperature range (273 to 453 K) and 26.4 meV for the low-temperature range (163 to 273 K) were obtained. Phonon-assisted and defect-assisted thermal field emission mechanisms from p-type CuO NWs were proposed to explain the observed phenomena in the two temperature ranges, which relate to the defect-induced localized states. Numerical simulation using the proposed mechanism was carried out and a good fit with the experimental results was achieved. The results suggest that defect-induced localized states play an important role in field emission from nanowires.

A detailed studies were conducted to explore the electrochromic properties and relative near infrared absorption mechanism of the newly prepared W[O.sub.3] nanowire films. The results indicate that the W[O.sub.3] nanowire films show excellent electroschromic properties, including a rapid response time and a large contrast ratio between the bleached and the colored states.

Hydrothermal syntheses of microstructures of semiconducting ZnO are reported. Top- and bottom-closed, single-crystalline hexagonal microtubes of ZnO exhibiting wide emission in the UV-visible range are successfully fabricated by a facile, template and base-free hydrothermal growth.

The field electron emission current from graphene is calculated analytically on a semiclassical model. The unique electronic energy band structure of graphene and the field penetration in the edge from which electrons emit have been taken into account. The relation between the effective vacuum barrier height and the applied field is obtained. The calculated slope of the Fowler-Nordheim plot of the current-field characteristic is in agreement with existing experiments. [ABSTRACT FROM AUTHOR]

We report our recent findings from the study of the field emission, electrical transport, and their correlation of individual single CuO nanowires grown by thermal oxidation. Typical Fowler-Nordheim (FN) plot of a single CuO nanowire exhibits an upward bending behavior with increasing applied electric field: a rare phenomenon of field emission from nanowires. The electrical transport measurement has shown that the CuO nanowire has a typical conductivity of 7.8×10-4 (Ω cm)-1. X-ray photoelectron spectroscopy study has given the energy band gap of 1.2 eV with Fermi energy level close to the top of valence band, confirming that the CuO nanowire is p-type. The upward bending FN plot can be explained using a field emission model of p-type semiconductor. [ABSTRACT FROM AUTHOR]

The image potentials of single-walled carbon nanotubes of various structures are calculated by using a quantum chemistry method. The image potentials are not sensitive to the applied fields and the structure of the tubes, but when the image potentials are included, the emission current has increased by one order.

The roles of field penetration, band bending and apex dipole in the field emitting, single-walled carbon nanotubes (SWCNTs) closed with a fullerene cap are examined. The predicted field emission performance of the H-terminated open SWCNT is shown to be slightly better than that of the closed SWCNT, as a C-H dipole is formed that has reduced the height of the tunneling barrier.

Large-Area aligned Mo nanowires are grown on stainless steel substrates by high-temperature chemical vapor deposition with the use of Mo metal. The detailed physical and chemical growth processes regarding the formation of the nanowires are investigated using mass spectroscopy, thermogravimetry and differential scanning calorimetry analysis as well as structure analysis by electron microscopy.

Quasi-aligned wurtzite AIN nanocones on catalyst-coated wafers with the preferential growth direction along the c-axis was successfully synthesized with the help of the reaction between AlCl3 vapor and NH3 gas around 700 degrees C. The unique photoluminescence and field emission properties of these novel AIN nanocones ensure their potential applications in light- and electron-emitting nanodevices.

Achieving high current emission from one-dimensional nanowire (NW) field emitters is essential for their application as X-ray sources. In this study, field emission (FE) from tungsten trioxide NWs (WO3 NWs) was studied, and defects were found to be responsible for the high electron emission current density. A high current density of 13.75 mA/cm² was achieved from large area, uniformly patterned, and defect-rich monoclinic WO3 NWs, which were grown directly on indium tin oxide (ITO) glass. Comparative investigations were carried out on the field emission properties of individual NWs with different defect concentrations. The results indicated that defect-related electrical transport was the source of such high emission current. This conclusion was further confirmed by a theoretical calculation that considered both defect-related electrical transport and Joule heating in the FE process. The conductivity induced by the defects increases with rising temperature, and this mechanism regulated the Joule heating during emission and helped to achieve high current density. Furthermore, a flat panel X-ray source device using as-grown defect-rich WO3 NWs as a cold cathode was fabricated and used to image various objects. Clear X-ray images with a spatial resolution of approximately 25 µm were obtained. [ABSTRACT FROM AUTHOR]

The vacuum breakdown critical condition of individual carbon nanotube (CNT) during field emission was investigated experimentally using the in-situ field emission combined scanning electron microscope system. The results showed that the critical breakdown electric field of CNT was related to its length and diameter. CNT which has a shorter length and larger diameter could bear higher electric field. The underlying mechanism was attributed to the heat dissipation ability of CNT. A smaller length and larger diameter CNT has better heat dissipation. The results met with the theoretical calculations and helped to understand the physics mechanism of vacuum breakdown of CNT during field emission in a visual perspective. [ABSTRACT FROM AUTHOR]

This paper reports for the first time the theoretical analysis, design, and realization of a microwave (MW) frequency multiplier based on a field emission from carbon nanotube (CNT) cold-cathode. The nonlinear characteristic of field emission from CNT cold-cathode is utilized for generating field emission current with the harmonics of input signal and achieving frequency multiplication. We demonstrated both theoretically and experimentally that an MW electric field is capable of inducting current with harmonics from CNT cold-cathode and that a direct-current (dc) electric field can effectively increase the amplitudes of the harmonics. A reentrant resonant cavity structure was designed and fabricated to deliver the desired combined MW and dc electric fields onto CNT cold-cathode and realize the MW frequency multiplier. The device has the target second harmonic at a frequency of 1.868 GHz and a third harmonic at 2.802 GHz with a driving signal at frequency of 0.934 GHz. By simply increasing dc bias, a 12.43-dB increase of the amplitude of target second harmonic is successfully obtained. With such a device, directly modulated electron beam with MW frequency harmonics is obtained. Both the principle and the design can find applications in frequency tunable vacuum electron devices. [ABSTRACT FROM AUTHOR]

In contrast to the conventional planar p-i-n photodiode and a metal-semiconductor-metal photodetector, the 3-D dual-gate photosensitive thin-film transistor (TFT) architectures presented here attain excellent photoresponse characteristics. Operating the device in the subthreshold regime further boosts the photoconductive gain as a result of light-induced decrease in the threshold voltage. This paper presents design considerations along with a performance comparison between 3-D photosensitive TFTs that have π- and FIN-shaped channels and conventional TFT with a planar channel. Our paper shows that the π-shaped structure tends to have a higher sensitivity while the FIN-shaped counterpart is more responsive with wider dynamic range. For both structures, a measured photoconductive gain of 104~106% is obtained with spectral responsivity ranging from near UV to near IR, and the photoresponse time in the range of tens of milliseconds. The 3-D dual-gate photosensitive TFT architecture appears to be very promising for large-area, low-level UV, visible, and IR detection applications. [ABSTRACT FROM AUTHOR]

Crystallinity and field electron emission characteristics of few-layer graphene (FLG) have been investigated synchronously by using in situ transmission electron microscope (TEM) to reveal their relationship. The crystallinity of a single FLG sheet is modified from polycrystalline to amorphous by TEM electron beam irradiation. In the meantime, the field electron emission measurement shows that the degradation of crystallinity has a negative effect on the field electron emission characteristics. This can be attributed to the violently decline of electrical conductivity of FLG. The results indicate that crystallinity is a key factor to the field electron emission of FLG, and thus, conditions leading to the degradation of crystallinity of FLG should be avoided [ABSTRACT FROM AUTHOR]

We report the featured gated field electron emission devices of Si nano-tips with individually integrated Si nano-channels and the interpretation of the related physics. A rational procedure was developed to fabricate the uniform integrated devices. The electrical and thermal conduction tests demonstrated that the Si nano-channel can limit both the current and heat flows. The integrated devices showed the specialties of self-enhancement and self-regulation. The heat resistance results in the heat accumulation at the tip-apex, inducing the thermally enhanced field electron emission. The self-regulated effect of the electrical resistance is benefit for impeding the current overloading and prevents the emitters from a catastrophic breakdown. The nano-channel-integrated Si nano-tip array exhibited emission current density up to 24.9 mA/cm² at a gate voltage of 94 V, much higher than that of the Si nano-tip array without an integrated nano-channel. [ABSTRACT FROM AUTHOR]

A transmission type flat-panel X-ray source in diode structure was fabricated. Large-scale patterned ZnOnanowires grown on a glass substrate by thermal oxidation were utilized as field emitters, and tungsten thin film coated on silica glass was used as the transmission anode. Uniform distribution of X-ray generation was achieved, which benefited from the uniform electron emission from ZnOnanowires. Self-ballasting effect induced by the intrinsic resistance of ZnOnanowire and decreasing of screening effect caused by patterned emitters account for the uniform emission. Characteristic X-ray peaks of W-L lines and bremsstrahlung X-rays have been observed under anode voltages at a range of 18-20 kV, the latter of which were the dominant X-ray signals. High-resolution X-rayimages with spatial resolution less than 25 μm were obtained by the flat-panel X-ray source. The high resolution was attributed to the small divergence angle of the emitted X-rays from the transmission X-ray source. [ABSTRACT FROM AUTHOR]

As one of the most important two-dimensional (2D) materials, BNnanosheets attracted intensive interest in the past decade. Although there are many methods suitable for the preparation of BN sheets, finding a cheap and nontoxic way for their mass and high-quality production is still a challenge. Here we provide a highly effective and cheap way to synthesize gram-scale-level well-structured BN nanosheets from many common graphite products as source materials. Single-crystalline multi-layered BN sheets have a mean lateral size of several hundred nanometers and a thickness ranging from 5 nm to 40 nm. Cathodoluminescence (CL) analysis shows that the structures exhibit a near band-edge emission and a broad emission band from 300 nm to 500 nm. Utilization of nanosheets for the reinforcement of polymers revealed that the Young's modulus of BN/PMMA composite had increased to 1.56 GPa when the BN's fraction was only 2 wt.%, thus demonstrating a 20% gain compared to a blank PMMA film. It suggests that the BN nanosheet is an ideal mechanical reinforcing material for polymers. In addition, this easy and nontoxic substitution method may provide a universal route towards high yields of other 2D materials. [ABSTRACT FROM AUTHOR]

A general approach to the coherent field electron emission of nanoemitters is proposed and applied to graphene. We will show that the coherence of the Dirac quasiparticles of graphene can be transmitted into the vacuum via electric-field-assisted electron emission at temperatures up to 1000 K. A dragonfly emission pattern with a dark body and two pairs of wings is predicted for the armchair edge as evidence of the pseudospin mixing and the odd parity of the n orbitals. Thus the phase information of the quantum states of the nanoemitters is revealed by the emission image. Moreover, this phenomenon leads to a novel coherent election line source that can produce interference patterns of extended objects with linear sizes comparable to the length of the graphene edge. The angular distribution of the emission and the total emission current will be given analytically. [ABSTRACT FROM AUTHOR]

A series of new aggregation-induced emission compounds with strong blue light-emitting properties derived from triphenylethylene were facilely synthesized by a Wittig–Horner reaction of bis(4-bromophenyl)methanone with diethyl 4-bromobenzylphosphonate, followed by a Suzuki reaction with arylboronic acids. Their maximum fluorescence emission wavelengths were 452–462 nm. The glass transition temperatures ranged from 70–145 °C, and the decomposition temperatures were 360–508 °C. The unoptimized device fabricated with benzofuranyl substituted compound as emitter turned on at ∼6 V, and the maximum luminance was ∼1500 cd m−2. [ABSTRACT FROM AUTHOR]

Various types of tungsten oxide nanostructures, including nanowires, nanobundles, and three-dimensional nanowire networks, have been synthesized on large-area silicon substrates by simply heating an array of tungsten filaments in a vacuum chamber. The fine structure and components of as-prepared products can been controlled by changing the tungsten filament temperature. This approach is free of catalysts and templates, and provides an economical method for large-scale preparation of various types of tungsten oxide nanostructures for applications. [ABSTRACT FROM AUTHOR]

Studies the field-emission properties of polymerized carbon nanofiber semiconductor film. Spatial distribution of emission sites of a nanofiber film; Field-emission patterns in carbon nanobells; Current-field characteristic of a carbon-nitrogen nanofiber film.