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The safety of animal-origin foods has a major influence on human health. Although the use of veterinary drug additives (VDAs) significantly promotes the normal growth and development of animals against diseases, the excessive consumption of VDAs is always the most worrying part. Thus, realizing a direct and prompt detection of solid VDAs is highly desirable. In this study, we incorporated a functional unit of triazolo [4,5-c] pyridine (TP) in polymer semiconductors. The theoretical simulation demonstrates that TP can effectively form hydrogen bonding with the VDA molecules. Furthermore, highly sensitive polymeric field-effect transistors (PFETs) are fabricated through the configurational design of low-dimensional polymer networks (LDPNs). The conducting channel and hydrogen bonding sites of the LDPN-based PFETs could be directly exposed to the analytes, thereby effectively capturing VDA molecules and converting the stimuli into electrical signals. The obtained PFET-based solid sensors showed highly sensitive and stable detection of melamine powders at a low operation voltage of −5 V. The detection limit realized is lower than the international standards in animal feeds (2.5 ppm). These results demonstrate the promising applications of PFETs for high-efficiency and low-power-consumption sensors for solid detection or biological diagnosis.

ConspectusPolymer-based organic field-effect transistors (OFETs) have attracted great attention owing to their significantly improved performance and the recently emerged prospects for broad applic...

Lightweight steel-aluminum structures have broad application prospects because of their lowering weight characteristics, however, the corrosion of welding-brazing joints in steel-aluminum structures is less concerned or studied. In this paper, the corrosion behavior of the laser-MIG (metal inert gas) hybrid welding-brazing joints of steel-aluminum is investigated through the tests and analysis of salt spray, immersion, and electrochemistry. The salt spray and immersion tests show that obvious galvanic corrosion occurs at the welded joints, in which the aluminum side is seriously corroded while the steel side is not corroded. The open-circuit potential (OCP) values of the aluminum alloy and the weld metal are similar (approximately −0.48 V), and the stainless steel has a higher OCP value of −0.33 V. The corrosion resistance of the weld metal is lower than aluminum- and steel-based materials. The corrosion resistance of the joints is controlled by the aluminum alloy part of the two metals based on the OCP and electrochemical impedance spectroscopy (EIS) analysis. A possible corrosion process schematic for the physical/chemical properties of a welding-brazing joint immersed in a sodium chloride solution is proposed according to EIS.

Two-dimensional (2D) materials have attracted great attention in recent years because of their unique dimensionality and related properties. Chemical vapor deposition (CVD), a crucial technique for thin-film epitaxial growth, has become the most promising method of synthesizing 2D materials. Different from traditional thin-film growth, where strong chemical bonds are involved in both thin films and substrates, the interaction in 2D materials and substrates involves the van der Waals force and is highly anisotropic, and therefore, traditional thin-film growth theories cannot be applied to 2D material CVD synthesis. During the last 15 years, extensive theoretical studies were devoted to the CVD synthesis of 2D materials. This Perspective attempts to present a theoretical framework for 2D material CVD synthesis as well as the challenges and opportunities in exploring CVD mechanisms. We hope that this Perspective can provide an in-depth understanding of 2D material CVD synthesis and can further stimulate 2D material synthesis.

Cyclopenta[b]thiopyran, isomeric to benzo[b]thiophene while isoelectronic to azulene, is involved as a building block to construct soluble organic semiconductors for field-effect transistors. Two series of angular-shaped heteroarenes based on cyclopenta[b]thiopyran, that is, Cn-SS (n = 4, 6, 8, 10) with different linear alkyl groups and C8-SS-Clm (m = 2, 3, 4) with chlorides substituted at different positions, have been straightforward synthesized. The obtained seven S-heteroarenes exhibit intriguing and similar photophysical and electrochemical properties, such as near-infrared absorption and high-energy levels of the highest occupied molecular orbitals. Nevertheless, the S-heteroarenes with identical π-conjugated skeletons demonstrate completely different molecular packing structures, which is proofed to be the key determinate factor for the charge carrier mobilities. Upon the engineering of the pendant alkyl lengths, the highest hole mobility in the Cn-SS series is achieved for C8-SS (1.1 cm2 V-1 s-1) with moderate alkyl length. The further incorporation of chlorides on C8-SS results in the shortened intermolecular H···S contacts and the interplane distances. Most interestingly, when chlorine-containing chloroform and chlorobenzene are used as crystallization solvents, single crystals of C8-SS-Clm with different packing structures are produced owing to the intermolecular interactions among the solute and solvent molecules. Upon further engineering of the chlorination position and the crystallization solvent, the maximum hole mobility in the ambient air improves to 2.7 cm2 V-1 s-1 for C8-SS-Cl2 crystallized from chlorobenzene, suggesting that the introduction of the accessible chlorides is a feasible pathway to engineering the crystal structures and controlling the charge transport characteristics.

Temperature-insensitive properties are attractive for most electronics, including polymeric semiconducting devices. Especially, polymeric field-effect transistors (FETs) with high mobility have been important research targets due to their broad applications. However, polymeric FETs with stable charge transport operating at extremely cold or hot zones are faced with enormous challenges. In this study, the polyacrylonitrile was found to significantly tune the sizes of pre-aggregates of polymers in solutions and the crystallinity of the polymeric films. The orientation of 5–25 μm linear grains in the films were prepared through the bar-coating process with polyacrylonitrile as an additive, which stabilized the electron mobility over a wide range of temperatures. The linear-grain morphology of the film contributed to reducing the holes and grain boundaries in the transport paths of carriers. Typically, the top-gate FETs based on P(NDI2OD-T2) displayed a stable electron transporting behavior from 200 to 460 K, with mobility greater than 3.5 cm2V−1s−1.

We propose and demonstrate an optical fiber vector curvature sensor based on a long-period fiber grating (LPFG) inscribed in Panda type polarization-maintaining fiber (PMF) using CO2-laser heating and tapering system. The uniform heating approach removes the necessity of CO2-laser exposure alignment along the axis of PMFs during grating fabrication. A serial of PMF-LPFGs with grating period from 350 to 490 $\mu \text{m}$ with a step of 20 $\mu \text{m}$ have been fabricated experimentally. The curvature response of the fast and slow axis resonance dips for the LPFG with a period of 450 $\mu \text{m}$ was investigated in the curvature range from 0 to 4.137 m−1 at four bending orientations. The maximum curvature sensitivities were measured to be 9.26 and −6.89 nm/m−1 for the fast and slow axis LP15 modes, respectively. The sensor can achieve 2-dimensional bending direction recognition. The proposed grating has potential application as a vector curvature sensor.

The increasing use of pesticides has raised concerns about the risks of exposure to pesticides. Rapid, simple and sensitive detection of pesticides is still a challenge in the current analytical technology. Herein, a perfluorinated copper phthalocyanine (F16CuPc) organic field-effect transistor (OFET) modified by β-cyclodextrin (β-CD) was used to detect boscalid molecules in solution. As a molecular carrier, β-CD will capture boscalid to form an inclusion complex. The hydroxyl group in β-CD and the carbonyl group in boscalid form a dipole–dipole interaction with F16CuPc, which induces more carriers in the device channel, which finally manifests as a significant increase in the maximum current of the device. When using β-CD as the modification layer, the detection limit of the device can be as low as 2.40 × 10−11 g L−1, which is 5 orders of magnitude lower than the internationally permitted MRL value.

Large scale synthesis of high-efficiency bifunctional electrocatalyst based on cost-effective and earth-abundant transition metal for overall water splitting in the alkaline environment is indispensable for renewable energy conversion. In this regard, meticulous design of active sites and probing their catalytic mechanism on both cathode and anode with different reaction environment at molecular-scale are vitally necessary. Herein, a coordination environment inheriting strategy is presented for designing low-coordination Ni2+ octahedra (L-Ni-8) atomic interface at a high concentration (4.6 at.%). Advanced spectroscopic techniques and theoretical calculations reveal that the self-matching electron delocalization and localization state at L-Ni-8 atomic interface enable an ideal reaction environment at both cathode and anode. To improve the efficiency of using the self-modification reaction environment at L-Ni-8, all of the structural features, including high atom economy, mass transfer, and electron transfer, are integrated together from atomic-scale to macro-scale. At high current density of 500 mA/cm2, the samples synthesized at gram-scale can deliver low hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) overpotentials of 262 and 348 mV, respectively.

Atomically thin solid-state channels enabling selective molecular transport could potentially be used in a variety of separation and energy conversion applications. The density of channels, their height, distance and edge structure are the key factors that dramatically impact the selective transport performance. However, such channels with small constrictions and atomic precision have been limited to proof-of-concept demonstrations based on microscale two-dimensional (2D) crystal stripes. Here, we report the engineering of highly ordered, scalable monolayer graphene crystallite arrays by chemical vapor deposition (CVD) method with a modified anisotropic etching approach. The size, shape, distance and edge structure of the graphene crystallite arrays in a large area could be delicately controlled through tailoring the synthetic parameters. This array structure can act as pillars to prop up a smooth single-crystal graphene film, and the fabricated integrated angstrom-size (3.4 A) channels allow water transport but exclude hydrated ions, demonstrating potential in selective ionic sieving and nanofiltration practice.

In 2004, graphene was successfully prepared by micromechanical exfoliation of graphite, which attracts wide attention in the scientific research community. After that, related research of two-dimensional (2D) materials has received continuous exploration. In particular, academia and industry have paid tremendous attention and high expectations on graphene, owing to its remarkable and tunable physical, electrical, optical, magnetic properties and its potential applications in various fields. These practical applications include high performance electronics and optoelectronics, such as field effect transistors, transparent and flexible electrodes, spintronic devices, solar cells and so on. However, as is well-known, the practical commercial applications are based on mature and repeatable preparation of materials. Great achievements have been made in developing synthesis techniques, including micromechanical exfoliation, epitaxial growth, chemical vapor deposition (CVD), chemical exfoliation, arc discharge, segregation growth and bottom-up synthesis and so on. Among these methods, CVD method is regarded as the most versatile platform to obtain high quality, large area, and controllable number of layers with good repeatability and low cost for real commercial applications. Up to now, the past decade has witnessed significant developments in the field of CVD graphene synthesis. Herein, we present the development of this field by firstly introducing the origin of graphene and the background of CVD method. Then, the main achievements in the development of graphene since 2008 are presented from the point of view of controllable preparation. The CVD synthesis of graphene is focused mainly on four aspects: the selection and modification of catalytic substrates, the manipulation of reaction conditions, bandgap engineering and clean transfer. The selection of catalytic substrate plays a critical role in the controllable preparation of graphene by CVD method. The representative catalytic mechanisms of different substrates for growing graphene are introduced, followed by various modifications of catalytic metal substrates. Besides, surface morphology and microstructure of substrates have a great impact on the quality and uniformity of as-grown graphene. Thus, due to the disadvantages of non-uniform surface energy, defects, wrinkles and impurities on the surface of solid metal, the introduction of liquid copper catalytic system helps to better control the nucleation uniformity and optimize the graphene growth. Moreover, the preparation of large-area monocrystalline metal foils for obtaining large-scale single-crystal graphene was also reviewed. In order to avoid the disadvantages such as the damage, wrinkle and polymer pollution of graphene associated with transfer process occurred in the cases of using metal substrates to grow graphene, direct synthesis of graphene on dielectric substrates is presented with focuses on two basic controls of nucleation density and growth rate. A series of techniques such as reaction medium regulation, substrate surface modification, and plasma-assisted growth, the introduction of gaseous metals and direct preparation of graphene on liquid glass are introduced. The development of graphene vertical and planar heterostructures with hexagonal boron nitride is also presented. Moreover, the disadvantage of graphene limits its application in logic circuits due to its zero bandgap without an acceptable on/off ratio, and three main ways to open graphene bandgap are discussed including doping, the preparation of a large area of AB stacking bilayer graphene and engineering graphene nanoribbons. After that, a brief introduction of transfer method used in graphene post-processing is given. Finally, we summarize the problems existing in the field, and the future opportunities and challenges are discussed.

In this article, we present detailed investigation of the high-performance long-period fiber gratings (LPFGs) based surrounding refractive index (SRI) sensors. A comprehensive design approach is proposed to optimize the sensitivity in a specific SRI range by combining adequately both dispersion turning point (DTP) and mode transition (MT) effects. The SRI sensitivity enhancement induced by the DTP and the MT is discussed respectively. The relative importance of the mechanisms in different SRI range is revealed. The mode transitions of the HE1,18 and HE1,20 are investigated in a single LPFG, where two high sensitivity ranges are obtained. The atomic layer deposition (ALD) technology is used to deposit the titanium dioxide (TiO2) nano-film on the LPFG surface. The SRI sensitivities of 1 × 104 nm /RIU in the SRI range 1.336–1.3397 and 4.2 × 104 nm/RIU in the range 1.4526–1.4561 are achieved, respectively. The experimental results are well consistent with the theoretical analysis.

Organic semiconductors for electronic devices have attracted much attention in scientific research and industrial applications. In the past few decades, functional organic field-effect transistors (OFETs) have developed rapidly, especially OFETs with memory function. Here, through a detailed introduction of the background, memory mechanism and structure construction, we make a comprehensive summary of memory applications based on OFETs. Further, we describe four types of OFET memories, i.e. floating-gate OFET memory, electret OFET memory, ferroelectric OFET memory, and optoelectronic OFET memory. Finally, we put forward challenges in the development of OFET memory and look forward to the future trend of the development of OFET memory.

Developing efficient and durable electrocatalysts with uniform sizes for the hydrogen evolution reaction (HER) in the entire pH range and seawater is critical for scalable and sustainable hydrogen production. Herein, we report a supramolecular starch-assisted confinement–assembly–pyrolysis (SCAP) strategy for the synthesis of ultrasmall Rh2P nanoparticles with high dispersion and low loading anchored on N,P-doped porous carbon (NPC). The Rh2P/NPC composite exhibits an unprecedented HER activity with small overpotentials at 10 mA cm−2 (40 mV in 0.5 M H2SO4 and 17 mV in 1 M KOH), as well as superior stability in both acidic and alkaline media. In addition, the Rh2P/NPC catalyst also exhibits an excellent HER performance in the entire pH range. Especially, the Rh2P/NPC catalyst shows an electrocatalytic HER activity superior to that of a 20% Pt/C catalyst in natural seawater, especially under large current densities. It only needs 160, 341 and 411 mV versus RHE to achieve current densities of 10, 100, and 300 mA cm−2, respectively. To the best of our knowledge, this Rh2P/NPC material is the best electrocatalyst reported thus far for seawater electrolysis. Moreover, the Rh2P/NPC catalyst also shows good stability over a wide range of current densities. All these results indicate that the Rh2P/NPC catalyst can be used as a robust catalyst for hydrogen production via direct seawater electrolysis. In situ X-ray absorption spectra revealed the strong interaction between the Rh–P site and H2O during the HER catalytic process in 1 M KOH, revealing the positive role of the Rh–P site in the HER. Theoretical calculations demonstrate that the strong synergistic effects between Rh2P nanoparticles and NPC modify the electronic structure to accelerate the HER kinetics. More interestingly, the SCAP strategy not only yields a robust and pH-universal HER catalyst, but also enables a general, green, and gram-scale synthesis of other metal phosphides.

As one of the basic units of optoelectronic devices, organic field-effect transistors (OFETs) are not only promising candidates for understanding the intrinsic charge transport mechanism of organic semiconductors (OSCs), but are also attractive for various applications, such as active-matrix displays, logic circuits, photodetectors, sensors and so on. Shrinking the active layer thickness in OFETs to a few molecular layers (MLs) or even down to a monolayer is a very attractive strategy in many aspects: (1) minimize material consumption while maintaining equal or even better charge transport properties, (2) reduce bulk injection resistance for the possible realization of Ohmic contact and short channel devices, (3) enhance phototransistor performance, (4) improve sensing performance, etc. In this review, we first comprehensively summarized the effect of active layer thickness on OFET performances in thin-film and single crystal devices in terms of mobility (μ) and contact resistance (Rc). Then the phototdetector and sensor applications of OFETs toward ultrathin two-dimensional (2D) molecular materials at the monolayer limit are discussed with emphasis on the high performance of monolayer molecular crystal (MMC) based devices. Finally, the challenges and perspectives regarding the controllable preparation of MMCs and corresponding devices applications are discussed.

It is of great interest to link Raman scattering to the properties of disorders in graphene membranes, which provides an effective characterization method to probe atomic scale defects. The built-in stress effect on the defect densities of substrate-supported monolayer graphene membranes around wells is investigated. First, a modified phenomenological model is developed to depict the relationship between built-in stresses and defect-activated Raman intensities. To validate the rationality of the modified model, Raman spectroscopy is used to characterize stretched graphene membranes on different patterned substrates with micro-scale wells. The experimental data indicate that the intensity ratio of D mode to G mode ID/IG increases with the Raman test point approaching the well edge. According to the modified model, the increase of ID/IG means the rise of defect densities, which originates from the propagation of initial defects in graphene membranes under built-in tension. The underlying mechanism of defect density increasing phenomenon is that the built-in stresses provide the energy for defect propagations in stretched graphene membranes. Theoretical and experimental comparison well validates the rationality of the modified model. The work can provide a theoretical foundation for Raman characterization method of defect propagations in stretched graphene and applications of defective graphene-based nanodevices.

We demonstrate a L-band all-fibre erbium-doped laser mode-locked by nonlinear polarisation rotation. The use of a single gain segment with appropriate length and dispersion and a L-band optimised Brewster fibre grating as an in-fibre polariser enables the generation of 64-fs pulses at 1.59µm.

Facile synthesis and post-processing of covalent organic frameworks (COFs) under mild synthetic conditions are highly sought after and important for widespread utilizations in catalysis and energy storage. Here we report the synthesis of the chemically stable aza-fused COFs BPT-COF and PT-COF by a liquid-phase method. The process involves the spontaneous polycondensation of vicinal diamines and vicinal diketones, and is driven by the near-equilibrium growth of COF domains at a very low monomer concentration. The method permits in situ assembly of COFs and COF-GO hybrid materials and leads to the formation of a uniform conducting film on arbitrary substrates on vacuum filtration. When used as electrocatalysts, the as-prepared membranes show a fast hydrogen evolution reaction (HER) with a low overpotential (45 mV at 10 mA cm-2 ) and a small Tafel slope (53 mV dec-1 ), which are the best among metal-free catalysts. Our results may open a new route towards the preparation of highly π-conjugated COFs for multifunctional applications.

Effective screening of infectious diseases requires a fast, cheap, and population-scale testing. Antigen pool testing can increase the test rate and shorten the screening time, thus being a valuable approach for epidemic prevention and control. However, the overall percent agreement (OPA) with polymerase chain reaction (PCR) is one-half to three-quarters, hampering it from being a comprehensive method, especially pool testing, beyond the gold-standard PCR. Here, a multiantibodies transistor assay is developed for sensitive and highly precise antigen pool testing. The multiantibodies capture SARS-CoV-2 spike S1 proteins with different configurations, resulting in an antigen-binding affinity down to 0.34 fM. The limit of detection reaches 3.5 × 10-17 g mL-1SARS-CoV-2 spike S1 protein in artificial saliva, 4-5 orders of magnitude lower than existing transistor sensors. The testing of 60 nasopharyngeal swabs exhibits ∼100% OPA with PCR within an average diagnoses time of 38.9 s. Owing to its highly precise feature, a portable integrated platform is fabricated, which achieves 10-in-1 pooled screening for high testing throughput. This work solves the long-standing problem of antigen pool testing, enabling it to be a valuable tool in precise diagnoses and population-wide screening of COVID-19 or other epidemics in the future.

Direct SARS-CoV-2 nucleic acid testing with fast speed and high frequency is crucial for controlling the COVID-19 pandemic. Here, direct testing of SARS-CoV-2 nucleic acid is realized by field-effect transistors (FETs) with an electro-enrichable liquid gate (LG) anchored by tetrahedral DNA nanostructures (TDNs). The applied gate bias electrostatically preconcentrates nucleic acids, while the liquid gate with TDNs provides efficient analyte recognition and signal transduction. The average diagnosis time is ∼80 s, and the limit of detection approaches 1-2 copies in 100 µL of clinical samples without nucleic acid extraction and amplification. As such, TDN-LG FETs solve the dilemma of COVID-19 testing on mass scale that diagnosis accuracy and speed undergo trade-off. In addition, TDN-LG FETs achieve unamplified 10-in-1 pooled nucleic acid testing for the first time, and the results are consistent with PCR. Thus, this technology promises on-site and wide population COVID-19 screening and ensures safe world-reopening.

Organic-inorganic hybrid perovskites exhibit superior optoelectrical properties and have been widely used in photodetectors. Perovskite photodetectors with excellent detectivity have great potential for developing artificial photonic synapses which can merge data transmission and storage. They are highly desired for next generation neuromorphic computing. The recent progress of perovskite photodetectors and their application in artificial photonic synapses are summarized in this review. Firstly, the key performance parameters of photodetectors are briefly introduced. Secondly, the recent research progress of photodetectors including photoconductors, photodiodes, and phototransistors is summarized. Finally, the applications of perovskite photodetectors in artificial photonic synapses in recent years are highlighted. All these demonstrate the great potential of perovskite photonic synapses for the development of artificial intelligence.

The fast spread of SARS-CoV-2 has severely threatened the public health. Establishing a sensitive method for SARS-CoV-2 detection is of great significance to contain the worldwide pandemic. Here, we develop a graphene field-effect transistor (g-FET) biosensor and realize ultrasensitive SARS-CoV-2 antibody detection with a limit of detection (LoD) down to 10-18 M (equivalent to 10-16 g mL-1) level. The g-FETs are modified with spike S1 proteins, and the SARS-CoV-2 antibody biorecognition events occur in the vicinity of the graphene surface, yielding an LoD of ∼150 antibodies in 100 μL full serum, which is the lowest LoD value of antibody detection. The diagnoses time is down to 2 min for detecting clinical serum samples. As such, the g-FETs leverage rapid and precise SARS-CoV-2 screening and also hold great promise in prevention and control of other epidemic outbreaks in the future.

In this paper, we proposed a novel narrowband filter based on long-period gratings (LPGs) in a triangular tri-core fiber (TCF). Both ends of TCF were connected with single-mode fibers (SMFs) to form SMF-TCF-SMF (STCS) fiber structure. The mode coupling properties of the STCS fiber structure without and with LPGs were investigated theoretically. The 3 dB bandwidths of transmission peaks in TCF-LPGs reduced with grating period number increasing from 35 to 90. With period number of 90, the 3 dB bandwidth could be achieved to be the narrowest of 9.11 nm. This novel narrowband filter could be applied in the fields of narrow-linewidth fiber laser and optical fiber communications.

Ambipolar polymer semiconductors are potentially serviceable for logic circuits, light-emitting field-effect transistors (LFETs) and polymer solar cells (PSCs). Although several high-performance ambipolar polymers have been developed, their optoelectronic devices are generally processed from toxic chlorinated solvents. To achieve the commercial applications of organic FETs (OFETs), the polymers should be processed from nonchlorinated solvents, instead of chlorinated solvents. However, most conjugated polymers show poor solubility in nonchlorinated solvents. It is of great importance to develop ambipolar polymers that can be processed from nonchlorinated solvents. Here, we develop a nonchlorinated solvent processed polymer named poly[7-fluoro-N, N′-di(4-decyltetradecyl)-7′-azaisoindigo-6′,6″-(thieno[3,2-b]thiophene-2,5-diyl)-7‴-fluoro-N″, N‴-di(4-decyltetradecyl)-7″-azaisoindigo-6,6‴-([2,2″-bithiophene]-5,5″-diyl)] (PITTI-BT) by designing a monomer with a large molar mass. The polymer displays good solubility in p-xylene (PX). Well-aligned films of PITTI-BT are achieved by an off-center spin-coating (SC) method. Based on the high-quality films, the OFETs fabricated from PX solution achieve record ambipolar performance with hole and electron mobilities of 3.06 and 2.81 cm2 V−1 s−1, respectively. The combination of nonchlorinated solvents and good alignment process offers an effective and eco-friendly approach to obtain high-performance ambipolar transistors.

Intrinsically stretchable organic field-effect transistors (STOFETs) that behave much like skin, have garnered widespread attention and demonstrated potential to more comfortable wearing electronics. Despite considerable efforts being exerted in stretchable hybrid polymeric semiconductors to achieve high-mobility and high-stretchability STOFETs, carbon nanotubes (CNTs) as ideal electrode materials, its interfacial quality seldom attracts research interests. Herein, we demonstrate a novel and general strategy on flexible CNT-based heterojunction electrodes by pentacene modification layer to enable high-performance and functional STOFETs. Pentacene transition layer can reduce the surface roughness and tune the heterogeneity of functional groups on the CNT thin film, as well as enhance the compatibility and van der Waals contact between CNT electrodes and organic semiconductors. The experimental results reveal that the carrier mobility of the resulting STOFETs increases by 2-3 times and the subthreshold slope decreases by 5 times compared with unmodified devices. The on-current/off-current ratio reaches nearly 107, which is approximately 1000 times as high as unmodified devices, and the highest value for stretchable organic transistors reported so far. Furthermore, STOFETs with heterojunction electrodes demonstrate better performance homogeneity and higher strain-independent capability. Noteworthy, these are the first intrinsically stretchable organic phototransistors (STOPTs) with superior photoswitching performances and high strain tolerance developed.

A semiconducting photoresist contributes to precise and reliable manufacture of highly integrated organic electronics., Owing to high resolution, reliability, and industrial compatibility, all-photolithography is a promising strategy for industrial manufacture of organic electronics. However, it receives limited success due to the absence of a semiconducting photoresist with high patterning resolution, mobility, and performance stability against photolithography solution processes. Here, we develop a comprehensive semiconducting photoresist with nano-interpenetrating structure. After photolithography, nanostructured cross-linking networks interpenetrate with continuous phases of semiconducting polymers, enabling submicrometer patterning accuracy and compact molecular stacking with high thermodynamic stability. The mobility reaches the highest values of photocrosslinkable organic semiconductors and maintains almost 100% after soaking in developer and stripper for 1000 min. Owing to the comprehensive performance, all-photolithography is achieved, which fabricates organic inverters and high-density transistor arrays with densities up to 1.1 × 105 units cm−2 and 1 to 4 orders larger than conventional printing processes, opening up a new approach toward manufacturing highly integrated organic circuits and systems.

Sensors based on graphene are promising devices for chemical and biological detection owing to their high sensitivity, biocompatibility, and low costs. However, for chiral recognition, which is very important in biological systems, graphene sensors remain unable to discriminate enantiomers. Here, using chiral pesticide molecules as an example, we realized a highly sensitive graphene chiral sensor by modification with acetylcholinesterase (AChE). Quantum chemical simulations indicate that the inhibition effect of the enantiomer on AChE was transferred to graphene, which allowed for the electrical detection of chiral molecules. Under an operating voltage of 1 V, the sensitivity of the device reached 0.34 μg/L and 0.32 μg/L for (+)/(-)-methamidophos, respectively, which is much higher than by circular dichroism (6.90 mg/L and 5.16 mg/L, respectively). Furthermore, real-time, rapid detection was realized by combining with smartphones and wireless transmission.

Stretchable organic field-effect transistors (STOFETs) employing organic semiconductors as active layers are highly attractive ongoing from health monitoring to biological research owing to some favorable advantages over their inorganic counterpart, including light weight, low cost, solution processing, high flexibility and simple adjustment of functionalities through molecular design. Although the development of STOFETs with original electrical performances under large mechanical deformation remain rudimentary, major efforts have recently been devoted to the investigation on STOFETs, and remarkable advances in stretchable components and novel fabrication methods have been achieved. A detailed overview of the advantages, challenges and current achievements in STOFETs was given including stretchable electrodes, semiconductors, dielectrics and substrates. Furthermore, conclusions and prospects for the future development of STOFETs with both high stretchability and superb electrical performances fabricated using intrinsically stretchable components are proposed.

Organic thin-film transistor (OTFT) has attracted considerable research interest in the past decades because of its great potential on flexible electronic applications. So far, there is still a big challenge to integrate high electrical properties and mechanical bending stability in single OTFT via a simple approach. A type of dielectric material possessing excellent flexibility, insulating property, compatibility with multiple organic semiconductors, and easy maneuverability are desirable. In this letter, the OTFT based on polyphenyleneoxide (PPO) dielectric, selected out from 10 different kinds of common polymers, shows invariant high mobility of around 1.5 cm2/Vs even after 5000-times mechanical bending with a small bending radius of merely 4 mm. Whereas the mobilities of OTFTs based on other polymeric dielectrics, such as PS and PMMA, obviously decrease within 100-times bending. Subsequently, flexible oscillators have also been fabricated based on PPO dielectric, which show negligible change on electrical performance after 500-times mechanical bending.

二维六方氮化硼是一种理想的石墨烯电学器件介电层材料, 然而, 制备低成本和高质量的氮化硼材料仍是一个挑战. 本文使用等离子体化学气相沉积法, 500°C下在铜箔衬底上制备了三角形的BN晶畴及其薄膜. 通过使用锡箔纸包裹原料的方法避免了残留原料在BN表面的沉积. 当BN作为石墨烯场效应晶体管的介电层时, 基于石墨烯的场效应器件空穴与电子的迁移率分别为10500和4750 cm2 V‒1 s‒1, 明显优于在高温条件下制备的BN作为介电层的石墨烯器件, 间接表明了该方法可得到高质量的BN. 另外, 本工作也揭示了氮化硼的质量对石墨烯场效应器件的性能至关重要.

Organic field-effect transistors (OFETs) have received significant interest due to potential applications from low-cost active circuit to wearable health care devices. Organic semiconductors as one of the key components in OFETs have drawn great attentions during last decades. Among them, antiaromatic and quinoidal materials have become the most intensively studied semiconductors. Therefore, this review describes the chemical structures and efficiency characteristics of π-conjugated materials through antiaromaticity and quinoid strategy for OFETs. In addition, rational designs and synthetic methods for these materials will be summarized, and a practical guideline for accelerating the development of high-performance semiconducting materials and devices will be provided.

Due to ultra-high reactivity, direct determination of free radicals, especially hydroxyl radical (•OH) with ultra-short lifetime, by field-effect transistor (FET) sensors remains a challenge, which hampers evaluating the role that free radical plays in physiological and pathological processes. Here, we develop a •OH FET sensor with a graphene channel functionalized by metal ion indicators. At the electrolyte/graphene interface, highly reactive •OH cuts the cysteamine to release the metal ions, resulting in surface charge de-doping and a current response. By this inner-cutting strategy, the •OH is selectively detected with a concentration down to 10−9 M. Quantitative metal ion doping enables modulation of the device sensitivity and a quasi-quantitative detection of •OH generated in aqueous solution or from living cells. Owing to its high sensitivity, selectivity, real-time label-free response, capability for quasi-quantitative detection and user-friendly portable feature, it is valuable in biological research, human health, environmental monitoring, etc., Field effect transistors based on graphene hold promise for future sensing applications. Here, the authors report a free radical sensor in which the •OH radical cuts cysteamine to release Cd2+ from the electrolyte/graphene interface and selectively detects •OH with a concentration down to 10−9 M.

Lead halide based organic-inorganic hybrid perovskite (HPVK) materials combine the advantages of solution processing, high absorption coefficient, long charge diffusion length, and high mobility of inorganic framework. The recent interest in this field is mainly focused on solution-processable HPVK for energy conversion and different types of optoelectronics. The performance of HPVK optoelectronics is rivaling now that of conventional devices, but the stability of the HPVK device is now a major challenge in the field where chemists are expected to play more active roles. This Perspective summarizes the progress in the understanding of mechanism of the HPVK formation, and various applications in different fields such as solar cells, light-emitting diodes, lasers, photodetectors, and field-effect transistors. A personal view of the past developments and future challenges is also provided.

Summary Compared with traditional silicon electronics, electronic devices based on organic field-effect transistors (OFETs) offer unique advantages, including mechanical flexibility, solution processability, and tunable optoelectronic properties. During the past several years, impressive advances have been made in OFETs, particularly in conjugated polymer-based FETs. Numerous FETs based on high-performance polymers have been developed thanks to the efforts of material design and device optimization. A remarkable mobility of more than 10 cm2 V−1 s−1 has been achieved in OFETs, which provides a promising opportunity for applications in flexible displays and wearable devices. This review describes the recent progress of this field from four aspects: basic knowledge, material design strategies, solution-processable techniques, and functional applications of OFETs. In addition, the current challenges and future outlook of this field are briefly discussed.

Direct and sensitive short-wavelength ultraviolet (UVC) dosimeters could provide a safer disinfection environment against viruses. We developed direct, quantitative, specific and highly sensitive UVC dosimeters based on DNA nanostructure-modified graphene field-effect transistors. Detectable doses of the dosimeters range from 0.005 to 6 kJ m−2 and such dosimeters have at least 5 times better sensitivity than the current direct UV dosimeters.

Background:RBMS3 (RNA-binding motif, single-stranded-intervacting protein 3) acts as a tumor-suppressive gene in a number of human cancers, however, its role in breast cancer is not fully understood. This study aimed to investigate the expression and clinicopathological significance of RBMS3 in breast cancer.Methods:A total of 998 breast cancer tissue samples in The Cancer Genome Atlas (TCGA) database with survival outcomes were divided into high RBMS3 expression and low expression groups using the median as the cutoff. Clinicopathological characteristics and prognosis were compared between the 2 groups.Results:TCGA showed that RBMS3 mRNA was downregulated in breast cancer tissues, and RBMS3 downregulation was correlated with poor prognosis. Immunohistochemistry staining of 127 paraffin-embedded breast cancer tissues showed that RBMS3 protein was localized in the cytoplasm and nucleus; however, nuclear staining was present in 90.0% of normal breast tissues but only 28.3% of breast cancer tissues. Decreased RBMS3 protein expression was significantly correlated with estrogen receptor (ER)-negative status and death at final follow-up. Patients with lower RBMS3 protein expression had substantially shorter survival than those with higher RBMS3 expression. Univariate and multivariate analysis indicated that the combination of RBMS3 expression and ER status (a variable designated as “cofactor”) was an independent prognostic factor in patients with breast cancer (hazard ratio [HR] = 0.420, 95% confidence interval [CI]: 0.223-0.791, P = 0.007).Conclusion:RBMS3 downregulation was correlated with poor prognosis in breast cancer patients, and the combination of RBMS3 expression and ER status was an independent prognostic factor.

ConspectusSince the rise of two-dimensional (2D) materials, synthetic methods including mechanical exfoliation, solution synthesis, and chemical vapor deposition (CVD) have been developed. Mechanical exfoliation prepares randomly shaped materials with small size. Solution synthesis introduces impurities that degrade the performances. CVD is the most successful one for low-cost scalable preparation. However, when it comes to practical applications, disadvantages such as high operating temperature (∼1000 °C), probable usage of metal catalysts, contamination, defects, and interstices introduced by postgrowth transfer are not negligible. These are the reasons why plasma-enhanced CVD (PECVD), a method that enables catalyst-free in situ preparation at low temperature, is imperatively desirable.In this Account, we summarize our recent progress on controllable preparation of 2D materials by PECVD and their applications. We found that there was a competition between etching and nucleation and deposition in PECVD, making it highly controllable to obtain desired materials. Under different equilibrium states of the competition, various 2D materials with diverse morphologies and properties were prepared including pristine or nitrogen-doped graphene crystals, graphene quantum dots, graphene nanowalls, hexagonal boron nitride (h-BN), B-C-N ternary materials (BCxN), etc. We also used mild plasma to modify or treat 2D materials (e.g., WSe2) for desired properties.PECVD has advantages such as low temperature, transfer-free process, and industrial compatibility, which enable facile, scalable, and low-cost preparation of 2D materials with clean surfaces and interfaces directly on noncatalytic substrates. These merits significantly benefit the as-prepared materials in the applications. Field-effect transistors with high motilities were directly fabricated on graphene and nitrogen-doped graphene. By use of h-BN as the dielectric interfacial layer, both mobilities and saturated power densities of the devices were improved owing to the clean, closely contacted interface and enhanced interfacial thermal dissipation. High-quality materials and interfaces also enabled promising applications of these materials in photodetectors, pressure sensors, biochemical sensors, electronic skins, Raman enhancement, etc. To demonstrate the commercial applications, several prototypical devices were studied such as distributed pressure sensor arrays, touching module on a robot hand for braille recognition, and smart gloves for recording sign language. Finally, we discuss opportunities and challenges of PECVD as a comprehensive preparation methodology of 2D materials for future applications beyond traditional CVD.

Free-Piston Energy Converter (FPEC) eliminates the crank connecting rod mechanism to realize variable compression ratio. This characteristic gives FPEC multi-fuel adaptability to achieve clean fuel power generation and higher efficiency. However, the lack of crank connecting rod mechanism makes FPEC susceptible to interference, and it is difficult to achieve stable operation. This paper focuses on the control method of Linear-Generator System (LGS) and the design of LGS controller. The LGS controller is composed of force controller and current controller. In Matlab / Simulink, we established the mathematical models of FPEC, where the LGS controller successfully realized the stable operation of FPEC with the target compression ratio, under the conditions of combustion fluctuations and external interference. And the tolerance of actual compression ratio is within 1%. Therefore, the control method is effective, and we can assume that FPEC as a range extender for hybrid vehicles has promising future adoption.

Research on aqueous solution sensor has immense demand in biological sensing applications. While traditional organic field-effect transistors (OFETs) have shown promising prospect in the field of sensing, their application in the aqueous solution sensing far lag behind since the aqueous environment strongly limits the organic materials to work. Here, we design, somewhat counterintuitively, an approach to increase the affinity of OFET to aqueous solution by adding amphiphilic molecule in the hydrophobic semiconductor. This method enables the aqueous solution sensing of the OFET through providing a good wettability between the OFET and the aqueous environment. Benefiting from this, the OFET can detect glucose aqueous solution in the human blood range (0.5–2 mg/mL) and the strongest response derived from the variation of mobility is as high as 5600% when applied 1 mg/mL glucose solution. Under a curvature radius of 7.5 mm, the OFET still maintains the sensitivity to glucose down to 0.5 mg/mL. The sensing performance is tunable through changing the amphiphilic molecule with different Hydrophile-Lipophile Balance value and introducing dielectric material in semiconductor. In addition, the selective detection to aqueous solutions of glucose, raffinose, starch, and lactic acid is realized. Portable real-time detection is achieved by integrating the OFET with wireless transmission and a smartphone. When the glucose concentration exceeds the limit, a red-light signal can be triggered as a warning. The work develops a simple approach for OFET to achieve aqueous solution detection.

A heterocycloarene derivative (S-Octulene) possessing two sulfur atoms was conveniently synthesized through Bi(OTf)3-catalyzed cyclization from a macrocyclic tetramethoxyethenylated precursor. The physical properties of S-Octulene and its supramolecular host-guest interaction with C60 and C70 were investigated by fluorescence titration and 1H NMR. The solution-processed organic field-effect transistor (OFET) measurements demonstrated that S-Octulene behaved as a p-type semiconductor with a hole mobility exceeding 0.01 cm2 V-1 s-1. Our findings pave a new path to design novel heterocycloarenes for the development of host-guest chemistry and organic semiconductors.

Recently, twisted two-dimensional (2D) bilayers have attracted intense interest due to the emergence of exotic physics in moiré superlattices arising from strong interactions between electrons in the two misaligned lattices. Accurate determination and control of crystallographic orientation is vital to construct twisted 2D bilayers. Here, we demonstrate a very simple method to visualize crystallographic orientation in various 2D crystals by directly imaging

Organic single crystalline semiconductors are highly desired for fabrication of integrated electronic circuits, yet the uniform growth and efficient patterning of them is a huge challenge. Here, a general solution procedure named soft-template-assisted-assembly method (STAA method) is developed to prepare centimeter-scale monolayer molecular crystal (MMC) arrays with precise regulation over their size and location via capillary confinement crystallization process. It is remarkable that the field-effect mobility of the array is highly uniform, with variation less than 4.4%, which demonstrates the most uniform organic single crystal arrays ever reported so far. Simulations based on fluid dynamics were carried out to understand the function mechanism of this method. Thanks to the ultrasmooth crystalline orientation surface of MMCs, high-quality p-n heterojunction arrays can be prepared by weak epitaxy growth of n-type material atop the MMC. The p-n heterojunction FETs show ambipolar characteristics and the corresponding inverters constructed by these heterojunctions exhibit a competitive gain of 155. This work provides a general strategy to realize the preparation and application of logic complementary circuits based on patterned organic single crystals. This article is protected by copyright. All rights reserved.

The exploration of highly active and stable noble-metal-free electrocatalysts for hydrogen and oxygen evolution reaction is a challenging task to achieve sustainable production of H2 through water splitting. Herein, we present the design and synthesis of a novel three-dimensional(3D)-networked heterogeneous nickel phosphide/sulfide electrocatalyst consisting of Ni2P strongly coupled with Ni3S2 in situ grown on Ni foam. Benefiting from the strong interfacial coupling effects between Ni2P and Ni3S2, large surface area, highly conductive Ni foam support, and the unique 3D open configuration, the optimal 3D-networked hybrid electrode exhibits superior electrocatalytic activity with extremely low overpotentials of 80 and 210 mV to deliver a current density of 10 mA cm−2 for HER and OER in 1.0 M KOH, respectively. Assembled as an electrolyzer for overall water splitting, this electrode delivers an impressive low onset potential of only 1.45 V and gives a current density of 10 mA cm−2 at a very low cell voltage of 1.50 V, which is dramatically superior to the current state-of-the-art electrocatalysts. In combination with density functional theory (DFT) calculations, this study demonstrates that the strong coupling interactions between Ni2P and Ni3S2 synergistically optimize the electronic structure and tune the hydrogen (or water) adsorption energy, thus significantly enhancing the overall electrochemical water-splitting activity. Our work might shed some new lights on the design and fabrication of efficient and robust three-dimensional hybrid electrode materials for a variety of electrochemical applications.

The commercialized aluminum electrolytic capacitors (AECs) currently used for alternating current (AC) line-filtering have low specific capacitances, making them usually the largest components in electronic circuits. Herein, an ultrathin free-standing graphene nanomesh film (GMF) with uniform and dense nanoholes has been successfully fabricated by an in-situ carbothermal reduction strategy on the basis of spontaneously assembled graphene hybrid film. Due to the carbothermal reduction reaction between carbon atoms of graphene and the metal oxide nanoparticles in-situ generated during assembly process, in-plane nanopores are generated within graphene film. The pore size and density of GMF can be conveniently tuned by annealing temperature. With large ion-accessible surface area, efficient ion diffusion and electron transport pathways, the typical GMF-based electrochemical capacitor (EC) exhibits a high volumetric capacitance of up to 7.6 F cm−3 at 120 Hz, unprecedented power density of up to 3000 W cm−3, ultrafast frequency response with a phase angle of −82.3°, and a short resistor-capacitor time constant of 0.32 ms at 120 Hz, as well as long-term cycling stability. The performances of these ECs are superior to those of the state-of-the-art carbon-based ECs for this purpose; thus, it is promising to replace commercialized AECs for AC line-filtering in future electronics.

The construction of highly active and stable non-noble-metal electrocatalysts for hydrogen and oxygen evolution reactions is a major challenge for overall water splitting. Herein, we report a novel hybrid nanostructure with CoP nanoparticles (NPs) embedded in a N-doped carbon nanotube hollow polyhedron (NCNHP) through a pyrolysis–oxidation–phosphidation strategy derived from core–shell ZIF-8@ZIF-67. Benefiting from the synergistic effects between highly active CoP NPs and NCNHP, the CoP/NCNHP hybrid exhibited outstanding bifunctional electrocatalytic performances. When the CoP/NCNHP was employed as both the anode and cathode for overall water splitting, a potential as low as 1.64 V was needed to achieve the current density of 10 mA·cm–2, and it still exhibited superior activity after continuously working for 36 h with nearly negligible decay in potential. Density functional theory calculations indicated that the electron transfer from NCNHP to CoP could increase the electronic states of the Co d-orbital a...

n-Channel organic light-emitting field-effect transistors (OLETs) based on perylene diimide (PDI-C13) with improved air stability were fabricated using a short channel length and thermal annealing. Both shortening of channel length and thermal annealing improved source–drain current; thermal annealing facilitated charge injection and improved PLQY of the PDI-C13 film. The light-emitting mechanism of OLETs was elaborated: that is, the OLETs were lateral organic light-emitting diodes in nature, the gate voltage (VGS) modulated light intensity by controlling electron density, and the light intensity was a quadratic function of VGS. This is the first example of n-channel OLETs that can operate in air.

This paper proposes a new approach for investigating the mechanism of the formation of the active phase of a hydrodesulfurization (HDS) catalyst via crystalline polyoxometalate (POM) precursors. The proposed strategy induces the crystallization of small Ni–Mo–O clusters in an impregnating solution by the coordinate bonding and supramolecular interaction of organic ligands to form POMs. By exploiting the “ligand-induced self-assembly” strategy, two Ni–Mo binary POMs with different frameworks, namely, Mo2Ni and PMo11Ni, were isolated from the impregnating solution by means of 4,4′-bpy. The sulfidation process of the precursors and the formation mechanism of the NiMoS active phase were fully characterized by a multi-technique approach that comprised, in particular, in situ FT-IR spectroscopy, XRD and Raman spectroscopy for different degrees of sulfidation. The results of the characterization revealed the structure-directing effects (framework effect, promoting effect and ligand effect) of the POM precursors on the structure of the active phase and even its HDS performance. MoS2 was formed at 200 °C from Mo2Ni, and the Ni species interacted with the edges of MoS2 to form the NiMoS active phase, whereas PMo11Ni formed MoS2 at 300 °C. The structure-directing effects enabled a higher content and better dispersion of the NiMoS active phase, which explains the higher HDS reactivity of sulfided Mo2Ni. The bottom-up self-assembly approach not only provides a better understanding of the composition of the impregnating solution and the formation mechanism of the NiMoS active phase but also sheds light on the rational design and controllable preparation of NiMoS catalysts with high performance.

Optoelectronic skin is acknowledged as the world current cutting-edge technology in the fields of wearable healthcare monitoring, soft robotics, artificial retinas, and so on. However, the difficulty in preparing stretchable photosensitive polymers and the high-crystallization nature of most reported photosensitive materials (such as perovskites) severely restrict the development of skin-like optoelectronic devices. Herein, a surface energy-induced self-assembly methodology is proposed to form easily transferrable and flexible perovskite quantum dot (PQD) films with a worm-like morphology. Furthermore, intrinsically stretchable phototransistors (ISTPTs) are fabricated based on an stretchable photosensitive layer heterojunction consisting of the worm-like PQD films and hybrid polymer semiconductors. The obtained ISTPTs display highly sensitive response to high-energy photons of X-ray (with a detection limit of 79 nGy s-1 , that is 560 times lower than commercial medical chest X-ray diagnosis) and ultraviolet (with photosensitivity of 5 × 106 and detectable light intensity of 50 nW cm-2 among the highest performance of reported photodetectors). In addition, these ISTPTs demonstrate desirable e-skin characteristics with high strain tolerance, high sensing specificity, high optical transparency, and desirable skin conformability. The surface energy-induced self-assembly methodology for the preparation of ISTPTs is a critical demonstration to enable low-cost and high-performance optoelectronic skins. This article is protected by copyright. All rights reserved.

The electron source still remains a major challenge for continuous-wave (CW) X-ray free-electron lasers (FELs). In this paper, we study the feasibility of an injection line based on a DC and superconducting radio-frequency (SRF) combined photocathode injector. We present a detailed investigation on the longitudinal phase space evolution of the electron beam along the injection line. We also analyze the main issues determining the high-order energy spread and current skewness. Based on the analysis, we propose to use a harmonic cavity as the buncher for the injection line. Simulation shows that an extracted electron beam with a normalized RMS emittance of 0.37 μ m, an RMS bunch length of 1.0 mm, a high-order RMS energy spread of 2.75 keV, and a current skewness of 0 can be obtained at the bunch charge of 100 pC. This study is meaningful to the design of the injection lines for short-wavelength CW FELs, including those based on normal-conducting very-high-frequency (VHF) guns or DC guns.