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There is a requirement for the development of methods for the preparation of well-controlled polymers with aggregation-induced emission (AIE) properties. This requirement directed this current work towards a robust synthetic route, which would be applicable for preparation in water and the presence of many types of functional groups. Herein, aqueous Cu-mediated living radical polymerization (LRP) has been optimized to provide facile and rapid access to a diverse range of water-soluble AIE polymers at sub-ambient temperatures. Homo-, block and statistical copolymerization all proceeded to a near full monomer conversion (≥99%) within 1 or 2 h and exhibited narrow dispersity, even when DP was targeted up to 1000. This excellent control associated with this polymerisation technique and the high-end group fidelity achieved were further demonstrated by linear first order kinetics and successful in situ block copolymerization, respectively. Fine-tuning the monomer sequence and composition of poly(N-isopropylacrylamide) (PNIPAM) copolymers allows for different lower critical solution temperature (LCST) and fluorescent thermoresponsive nanoparticles, which spontaneously self-assembled to varying sizes in water as determined by a combination of techniques (DLS, SAXS and TEM). Additionally, the fluorescence intensity was demonstrated to depend on the polymer concentration, architecture of the side chains and temperature. Particularly, PNIPAM-containing polymers were resistant to reduction in thermo-induced emission. The good biocompatibility, photostability and high specificity make them promising candidates as lysosome-specific probes for application in bioimaging.

The key problems restricting the wide development of Ti3AlC2 material are the low hardness and strength. In this paper, MAX phase Ti3(Al,Si)C2 solid solutions with different Si doping were successfully synthesized using an in-situ reaction of Ti–Al–C system by powder metallurgy route. The phase structures and microstructures of the as-synthesized Ti3(Al,Si)C2 solid solutions were analyzed, the mechanical properties were tested, and the fracture surface morphologies were characterized. The results show that doping Si can prevent the lath-like structure of MAX phase from coarsening. When doping 0.2 mol Si, the as-synthesized Ti3Al1.0Si0.2C2 sample offers fine microstructure and has excellent performance. Its Vickers hardness, flexural strength and the fracture toughness are 5.52 GPa, 546 MPa, 7.51 MPa m1/2, respectively. The fracture mode is transgranular cleavage fracture. During propagation, the main crack deflects and branches obviously. The crack extends in a zigzag like path, accompanied by transgranular fracture. When suffering external force, the particular layered structure of Ti3(Al,Si)C2 can absorbs and dissipates more energy through hybrid deformation modes such as extrusion, kink, fold, interlaminar separation and tearing. With this complex and mixed fracture mode, the crack propagation were effectively prevented, and its flexural strength and fracture toughness were enhanced.

Background Poly(3,4-ethylenedioxythiophene):poly-(styrenesulfonate) (PEDOT:PSS) is a promising conductive polymer for the flexible piezoresistive pressure sensor. However, intrinsic hydrophilicity is detrimental to its structural stability under moisture. The present study aims to enhance piezoresistive pressure sensors' stability to achieve the highly-reliable electronic device applications. Method ITO/PEDOT:PSS/ITO piezoresistive pressure sensors with an interdigitated electrode (IDE) structure and different metallic interfacial layers were fabricated. Au layer was introduced between PEDOT:PSS sensing membrane and indium tin oxide (ITO) electrode as a reaction-inhibited interfacial coating of piezoresistive pressure sensors. Significant findings After a measurement time interval of 6 months, the interface reaction suppressed significantly, resulting in low sensitivity deviation (9.22%) and improved durability (400 cycles). The devices are completely sealed using polyethylene terephthalate packaging, avoiding humidity absorption in PEDOT:PSS films successfully. The packaged ITO/PEDOT:PSS/ITO piezoresistive pressure sensors with a double-sided 10-nm-thick Au interfacial layer is a promising candidate for use in highly reliable pressure sensing applications.

Although remarkable improvement has been achieved in stretchable strain sensors, challenges still exist in aspects including intelligent sensing, simultaneous data processing, and scalable fabrication techniques. In this work, a strain-sensitive device is presented by fabricating a CsPbBr3 quantum dots (QDs) floating-gate field-effect transistor (FET) sensing array on thin polyimide (PI) films. The FET exhibits an excellent on/off ratio (>103) and a large memory window (>2 V). With the introduction of CsPbBr3 QDs as the trapping layer, an additional UV response is obtained because of the photogenerated charge carriers that significantly enhance the source-drain current (IDS) of the device. At each electrical state, the IDS varies with the strains and the sensing range is from compressive +12.5% to tensile -10.8%. Excellent data retainability and mechanical durability demonstrate the high quality and reliability of the fabricated sensors. Furthermore, synapse functions including long-term potentiation (LTP), long-term depression (LTD), etc., are emulated at the device level. Linearity factor changes of LTP/LTD in different sensing scenarios demonstrate the reliability of the device and further confirm the different sensing mechanisms with/without UV illumination. Our results exhibit the potential of transistor-based devices for multifunctional intelligent sensing.

The effect of natural aging on mechanical properties and bake hardening behaviors of Al-Mg-Si alloys was quantitatively investigated by a series of tensile experiments along the rolling direction. The natural aging period is from three days to three months after heat treatment. As the results, within three months, along the rolling direction, 0.2% offset yield strength and ultimate tensile strength respectively increased from 97 MPa to 145 MPa, 210 MPa to 248 MPa. The strain hardening exponent n-value and the increment of yield strength after bake hardening respectively decreased from 0.2804 to 0.2186, 127 MPa to 89 MPa. The percentage elongation after fracture varies from 22% to 24% during natural aging and varies from 13% to 16% after bake hardening. A large amount of detailed data has been given, which quantitatively describes the change in mechanical properties and bake hardening behaviors of Al-Mg-Si alloys during natural aging.

It is of great significance to develop multifunction-integrated photoelectric synaptic devices with the simple structure to imitate the functions of eyes. In this work, we reported the multimodal photoelectric neuromorphic thin film transistors (TFTs) with single gate and two input terminals using sorted semiconducting single-walled carbon nanotubes (sc-SWCNTs) mixed with lead-free perovskite (CsBi3I10) and lightly n-doped silicon as active layers and gate electrodes. The results showed that optical and electrical responses of SWCNT TFTs could increase 26 and 23 times after addition of CsBi3I10 under the same pulse sequence stimulation, respectively. Apart from emulating a series of typical synaptic functionalities, an artificial neural network based on SWCNT phototransistors was simulated to be trained for the recognition of handwritten digits in the Modified National Institute of Standards and Technology with the maximum accuracy of about 85.46%. Moreover, our synaptic devices can imitate traditional Pavlovian conditioning, and show NOR logic, reproducible flash memory functions under the optical and electrical programming stimulations. It is noted that the erasing voltage (3 V, 0.2 s) is one of the best value among the reported phototransistor memory. Furthermore, our synaptic devices can work well after more than 150 programming/erasing operation cycles and over 40 days testing.

Summary Memristive devices offer desirable voltage-regulated conductance switching and promise to address zettabyte storage challenges in the big-data era. Generally, most of these reported devices use amorphous solids, where the structural and compositional inhomogeneity is regarded as the origin of stochastic variability. Self-assembling peptide crystals with solution-processed fabrication, controllable morphologies, and structural stability are therefore a promising candidate to address the reliability issues. Here we report a planar diffusive memristor that possesses reliable switching characteristics based on a quasi-one-dimensional crystallized material: diphenylalanine (FF) microrod (MR). This element offers a preferential ion migration path, confining conductive filaments in a defined crystalline surface and therefore reducing programming stochasticity. Ion transport confinement along FF MR was observed via in situ electrostatic force microscopy technique. Additionally, FF MR memristor with high switching uniformity and reproducible relaxation dynamic provides an ideal hardware platform for reliable nociceptor emulation and hardware identification of four-bit decimal numbers.

Photocatalysis has been regarded as a promising process for pollution removal and green energy. TiO2 nanofibers synthesized by the hydrothermal method presents high crystalline and performs excellently due to the efficient charge transport. For practical use, we designed an autoclave with a 1,000 cm3 of Teflon-liner inside and stainless steel outside for the hydrothermal synthesis of Ag/TiO2 NFs. Various parameters of the process, including reaction temperature, doping concentration, and calcination temperature, were investigated to provide a reliable and optimal process. Through the hydrothermal reaction, TiO2 particles transformed into sodium titanate nanorods, and further refilled the hollow channel. With the proton exchange using diluted hydrochloric acid, the precipitated Ag nanoparticles were leached but appeared again on the surface of Ag/TiO2 nanofibers after the calcination. Silver incorporation enhanced the absorption in the visible region and precipitated onto the TiO2 NFs surface after the optimal calcination, constructing the heterostructure. It dominated the photocatalytic performance of pollutant degradation and water splitting. The unveiling of silver surface precipitation gives a clear illustration in the scaled-up hydrothermal method of Ag/TiO2, providing an efficient way for nanomaterial fabrication.

Inspired by the TM−N4 coordination environment and the promising hydrogen adsorption property of the Ti–C4 unit, four novel TM6C24N24 (TM = Sc, Ti) cages with six TM−N4/TM−C4 units are designed simultaneously for the first time in this paper. Their stabilities are studied by using DFT calculations and confirmed by MD simulations. Sc6C24N24(N4) and Ti6C24N24(N4) can absorb 30 hydrogen molecules and keep the original structures intact. The average hydrogen adsorption energy is 0.13–0.26 eV for Sc6C24N24(N4)-6nH2 (n = 1–5), and 0.09–0.23 eV for Ti6C24N24(N4)-6nH2 (n = 1–5). The hydrogen storage capacities are 6.30 wt % and 6.20 wt %, respectively. Besides, the 30H2 can be readily adsorbed on Sc6C24N24(N4) under 160 K and 100% desorbed at 270 K under 0.1 MPa. The desorption temperature could increase if the pressure becomes higher. Sc6C24N24(C4)/Ti6C24N24(C4) complexes are higher in energy than corresponding Sc6C24N24(N4)/Ti6C24N24(N4). They are not suitable as room-temperature hydrogen storage materials due to the structural deformation in the hydrogen storage process.

Using structural phase transitions to enhance electrochemical properties without has received wide attention due to its large active area and excellent electron transport capacity. In this work, hollow C@SnS2/SnS nanocomposites were successfully synthesized from hollow C@SnS2 by controlling the temperature and time of the phase transitions. It is found that this hollow C@SnS2/SnS nanocomposite can serve as electrocatalyst, showing excellent oxygen evolution reaction performance. The Sn (IV) heterostructure easily accepts electrons in water and plays a crucial role in the oxygen evolution reaction. Meanwhile, the low-valence Sn (II) can maintain a stable structure in the electrochemical reaction and thus exhibits good electrochemical performance with an overpotential of 380 mV, at the current density of 10 mA cm−2, and a low Tafel slope of 63 mV dec−1, which is far lower than that of pure SnS or SnS2.

Nonvolatile memory is distinguished for the application in many electronic products due to its excellent charge storage ability. Nevertheless, as the device dimensions are scaled down, floating gate memory encounters various challenges: the increasing leakage current leading to a serious reliability issue and the decreasing of charge density. Hence, metal nanoparticle‐based floating gate memory has been proposed and become a promising candidate for nonvolatile memories due to its outstanding operation speed, excellent scalability, and favorable reliability. This review briefly introduces the classification of memory devices. The operation mechanisms, fabrication and characterization of metal nanoparticle‐based floating gate memory are discussed based on research activities reported in recent years.

Fused (hetero)cyclic polymers are important functional polymers with wide applications in photoelectronic fields due to their unique photophysical properties. However, traditional synthetic methods toward such polymers normally require limited and expensive fused aromatic substrates, elaborate reaction control, complicated operation procedures, and painful isolation. These synthetic difficulties greatly restrict their accessibility. C–H-activated polyannulations of acetylenic monomers offer a facile and efficient way for the synthesis of fused (hetero)cyclic polymers by utilizing inert C–H as potential functional groups. With this strategy, complex fused (hetero)cycles can be generated in-situ in polymer backbones from simple and readily available reactants. Herein, recent progress on alkyne-based polyannulations derived from C–H activated reactions will be summarized with representative examples. The properties and functionalities of the obtained fused (hetero)cyclic polymers will also be introduced.

This article provides a review of current development and challenges in memristor modeling. We review the mechanisms of memristive devices based on various classifications and survey the progress of memristive models and simulations. Except for classical models in theory, different modeling architectures are compared, including first-principle, modular dynamics and the finite element tools like COMSOL and MATLAB. Challenges and strategies for memristors with non-ideal mechanisms, including large parameter variations, modeling algorithms and simulation roadblocks are also discussed.

Cellulose nanocrystals (CNCs) are the most commonly used natural polymers for biomaterial synthesis. However, their low dispersibility, conductivity, and poor compatibility with the hydrophobic matrix hinder their potential applications. Therefore, we grafted sulfate half-ester and carboxylic functional groups onto CNC surfaces (S-CNC and C-CNC) to overcome these shortcomings. The effect of the dopants, surfactant ratios, and properties of CNCs on the thermal stability, conductivity, and surface morphology of polyaniline (PANI)-doped CNC nanocomposites were investigated through emulsion and in situ polymerization. The higher electrical conductivity and well-dispersed morphology of SCNC–PANI30 (1.1 × 10−2 S cm−1) but lower thermal stability than that of CCNC–PANI30 (T0: 189 °C) nanocomposites are highly related to dispersibility of S-CNCs. However, after 4-dodecylbenzenesulfonic acid (DBSA) was added, the conductivity and thermal stability of SCNC/PANI increased up to 2.5 × 10−1 S cm−1 and 192 °C with almost no particle aggregation because of the increase in charge dispersion. The proposed biodegradable, renewable, and surface-modified S-CNC and C-CNC can be used in high-thermal-stability applications such as food packaging, optical films, reinforcement fillers, flexible semiconductors, and electromagnetic materials.

Dielectric polymers with high electrostatic energy storage capability are the enabling technology for advanced electronics and electric power systems. However, the development of dielectric polymers is rather limited by their undesired discharged energy density (Ue) due to the intrinsic low dielectric constant (K). Although large improvements of K can be achieved in dielectric polymers by introducing high filling ratios (>10 vol%) of high-K inorganic fillers, this approach has had only limited success in enhancing energy density due to the negative impact on the breakdown strength (Eb) and charge–discharge efficiency (η). Herein, we report that the incorporation of ultralow amounts ( 87% at 800 MV m−1. The improvement ratios of K (∼69%) and Eb (∼60%) reported in this work represent the record values in linear dielectric polymer composites with low filler content (≤5 vol%). The observed dielectric enhancement is rationalized by the significant contributions of the interface including enhanced polymer chain mobility and induced interfacial dipoles as revealed in the interphase dielectric model and interface simulations based on density functional theory (DFT). The improved mechanical strength and raised interface charge barriers are responsible for the high Eb. This contribution paves a new avenue for designing scalable polymer-based dielectric materials exhibiting high energy densities and efficiencies and provides fundamental insights into the dielectric behaviors at the interfaces in polymer nanocomposites.

Recently, mainstream silicon (Si)-based materials and complementary metal oxide semiconductor (CMOS) technology have been used in developing extremely tiny sized (of a few nanometers) devices. However, with the reduction of transistor characteristic dimensions, many new challenges such as the short channel effect and high heat dissipation problems have emerged. Two-dimensional transition metal dichalcogenides (2D TMDs) are deemed the most promising semiconductor materials to conquer the challenge of the short channel effect owing to their excellent properties, including high mobility and atomic thickness. Nevertheless, Fermi-level pinning (FLP) occurs when TMDs are in direct contact with metal electrodes, which causes an uncontrollable Schottky barrier and a high contact resistance, limiting the device performance. In this review, we summarize the recent progress on how to circumvent FLP between 2D TMDs semiconductors and metals. Firstly, the related concepts, aiming to get an in-depth understanding of FLP are introduced. Secondly, we discuss the factors contributing to FLP in detail and the strategies of Fermi-level depinning according to these factors. Finally, we present a summary and outlook, which will provide a guideline for suppressing FLP in the process of fabricating high-performance 2D TMD devices.

Resistive random access memories (RRAMs) based on the electrochemical metallization mechanism (ECM) have potential applications in high-density data storage and efficient neuromorphic computing. However, the high variability of ECM devices still hinders their application in artificial intelligence owing to the random formation of conductive filaments (CFs). Here, we demonstrate 2D covalent organic framework (COF) RRAM with electroforming-free resistive switching behavior, low spatial/temporal variations, and excellent retention capability up to 105 s. The one-dimensional channels of the oriented COF-5 film can not only confine the shape of filaments but also modulate the transition direction of Ag ions. Moreover, alcohol vapors could activate the device to achieve gas-mediated multilevel resistive switching since COF materials can absorb small molecules through host guest interactions to vary the conductivity. An alcohol gas recognition system constructed by integrating the COF RRAM as a sensor and filter part with the k-nearest neighbors (KNN) algorithm as a classifier was demonstrated with a recognition accuracy of 87.2%. Furthermore, the effect of alcohol inhibition stimulation in the human nervous system is successfully emulated by the COF RRAM.

The saturation of Moore's law and the finality of Dennard scaling highlight the need for new data-storage approaches employing different physical mechanisms. Due to the low operation voltage, multibit storage and cost-effective manufacturability, memristive devices are considered to be one of the most attractive alternatives to conventional silicon-based memory. Typically, memristive devices can be switched to a low resistance state or a high resistance state by electrical SET/RESET operations, respectively. Recent years have witnessed a surge of research interest in optoelectronic memories, where tunable switching characteristics, coexistence of volatile and non-volatile behaviours, multilevel programming capability and programming/erasing steps can be achieved optically. In this work we introduce an electro-photoactive memristive device based on natural melanin with favorable electrical and optical properties. The device shows reproducible bipolar resistive switching with a low SET voltage (0.2 V) and an ON/OFF ratio over 104. The SET voltage can be easily tuned from 0.2 V to 1.2 V by varying the wavelength or the intensity of the optical input. Due to this phototunable switching characteristic, light-driven switchable NAND and NOR operations have been realized on a melanin-based circuit.

Resistive random access memory (RRAM) based on hybrid organic–inorganic halide perovskite (HOIP) materials has recently gained significant interest due to its low activation energy of ion migration. HOIP RRAM has been reported to exhibit outstanding performance, but they still suffer from issues of high operating voltage and poor uniformity. Here, we provide an efficient method for improving the resistive switching characteristics of HOIP RRAM by integrating an Au tip in the bottom electrode to regulate the growth of conductive filaments (CFs). The Ag/polymethylmethacrylate/CH3NH3PbI3/Au tip/indium tin oxide RRAM exhibits a lower set voltage of −0.11 V, a larger ON/OFF ratio of 108, excellent durability (up to 4 × 103 times), low power consumption, and good non-volatility. Moreover, the time-dependent resistive switching characteristics were investigated by a statistical analysis of the data on the turn-on time based on the Weibull distribution. Tests using transmission electron microscopy, electron energy depletion spectroscopy, and energy dispersive spectroscopy have demonstrated that the formation and rupture of CFs occur mainly in the CH3NH3PbI3 layer and that the CFs should be composed of Ag atoms and I vacancies. Our research offers a strategy for enhancing the stability of perovskite devices and promoting the application of low-power, high-density non-volatile memory devices.

Neuromorphic computing inspired by the functions of human brain has attracted much attention in the research area of artificial intelligence. Herein, we report an optoelectronic synapse based on a polyvinylpyrrolidone (PVPy)-upconverting nanoparticle (UCNP) hybrid floating gate transistor. The UCNP-based synaptic transistor exhibits a remarkable near-infrared (NIR)-induced de-trapping behaviour as well as a long retention time. Furthermore, our device is employed to successfully emulate various synaptic functions including postsynaptic current with different duration times and pulse amplitudes, paired-pulse facilitation/depression, transition from short-term plasticity to long-term plasticity and learning-forgetting-relearning processes. Overall, this work may open up a new opportunity for NIR optoelectronic synapses.

The introduction of aggregation-induced emission (AIE) moieties into polymers results in smart materials with AIE characteristics, expanding their scope of applications. Herein, well-defined polymers with controlled molecular weight, low dispersity, and high end-group fidelity are produced via copper(0)-mediated reversible-deactivation radical polymerizations (Cu(0)-RDRPs). An AIE-containing initiator tetraphenylethene bromoisobutyrate (TPEBIB) has been synthesized, fully characterized, and utilized for the construction of different polyacrylate homopolymers and block copolymers bearing the TPE group with a range of molecular weights and architectures. All of the polymers exhibited AIE behavior. Notably, the hydrophobic TPE-poly(

Here, we report all-polymer polysiloxane composites that overcome the long-standing processing problems of silica-reinforced silicone rubbers. Polystyrene fillers are dispersed with styrene/dimethy...

A facile alkyne-based multicomponent polymerization route was developed for the construction of solution-processable fluoropolymers with multiple functionalities. The palladium-catalyzed one-pot po...

Hydrogen evolution reaction (HER) plays a key role in combating an ever-growing imbalance and adverse climatic issues. Thus far, Pt-based catalysts are treated as “the Holy Grail” for HER and none ...

Photothermal therapy (PTT) has emerged as one of the most promising cancer therapeutic tools owing to its advantages of minimal invasiveness, convenient operation, and low toxicity. Imaging techniq...

A rotor retaining sleeve is usually essential in high-speed permanent magnet (PM) motors to firmly retain the magnets and ensure the rotor integrity. The structure and material of retaining sleeve have a significant effect on rotor losses, especially on the rotor eddy current loss. On the other hand, heat dissipation from the rotor is difficult, therefore, any excessive rotor loss may lead to over temperature and cause irreversible demagnetization of the magnets. In this article, the influence of retaining sleeve with different structures and materials on the rotor eddy current loss in high-speed PM motors will be comprehensively investigated, with both 3-D finite element method simulations and experiments. Particularly, the proposed experiments are carried out with a stationary rotor. The study reveals that the equivalent conductivity of the retaining sleeve has a significant influence on the rotor eddy current loss, and countermeasures can be made accordingly so as to reduce the rotor eddy current loss.

In order to clarify the effects of the proportion of raw powders, heating temperature and holding time on the purity and properties of MAX phase Ti3AlC2, powder mixtures of Ti, Al and C powder with different ratio were prepared by planetary ball mill and heated under different conditions by spark plasma sintering. The microstructures and phase structures of the as-synthesized samples were characterized, the correlation between the mechanical properties and microstructure and fracture mechanism were investigated systematically. The results show that with the proportion of raw powders Ti:Al:C = 3:1.2:2, the sample heated at 1300 °C for 60 min has the highest purity 97.23 wt% of MAX phase. It has a compact and uniform lath-like structure with the length-thickness ratios of 3–5 and excellent comprehensive mechanical properties: the Vickers hardness, bending strength and fracture toughness are 5.26 GPa, 500 MPa and 7.35 MPa∙m1/2, respectively. The experimental results show that among the three factors, the proportion of raw powders has the greatest influence on purity of Ti3AlC2 phase, followed by heating temperature and holding time. The fracture morphologies of the tested samples demonstrate that under the action of external force, extrusion and kink occurred in the layered structures of Ti3AlC2 phase. These two forms of energy dissipation lead to the bending strength and fracture toughness of Ti3AlC2 are higher than that of traditional ceramics.

Perovskite solar cells (PSCs) have earned considerable attention and are candidates against the inevitable energy crisis. Even though various successful PSCs have emerged, increasing the PCE by reinforcing charge collection is still a critical issue. The manipulation of carriers between the perovskite active layer and the electron extraction layer (EEL) is essential. Here, we prepared a tin-doped TiO2 (Sn/TiO2) EEL that presented two main polymorphs, anatase and rutile, and successfully fabricated a high-performance planar PSCs. Besides, the band alignment between EEL and perovskite active layer could be optimized by tuning the Sn doping concentration and the ratio of anatase and rutile phases. The intrinsic conductivity, interface morphology, band alignment, and charge carrier dynamic were characterized and the relationship to the photovoltaic performance was clarified. As the Sn ions being doped into TiO2 structure, EEL presented the mixed TiO2 rutile/anatase phase, directly narrowing the bandgap and promoting mobility. Furthermore, the adjustment of the band structure can facilitate electronic transitions. Finally, a promising planar PSC with Sn/TiO2 phase junction EEL achieved a champion PCE of 15.4%.

As the power density of the electronics is on increasing, improving the heat dissipation performance of electronic packaging materials will play a positive role in promoting the performance of modern electronics. In this work, the three-dimensional carbon fiber (CF)-MXenes foam, in which the vertically aligned CF constructed the heat transport paths, were prepared by simple freeze-drying method. As a result, the thermal conductivity (TC) of CF-M/epoxy composites was improved to an ultra-high level (9.68 W/mK) at 30.2 wt% hybrid fillers, increasing by 4509% enhancement compared with that of neat epoxy. In addition, the thermal properties of composites, such as glass transition temperature (Tg), coefficient of thermal expansion (CTE) were investigated. All the results indicated that the CF-MXenes/epoxy composite was supposed to be a promising heat dissipation material and will be used in the field of electronic packaging.

Azide-alkyne click polymerization has become a powerful tool for polymer synthesis. However, the click polymerization between internal alkynes and azides is rarely utilized to prepare functional polymers. In this work, the polymerization reactions of activated internal alkyne monomers of tris(2-butynoate)s (1) with tetraphenylethene-containing diazides (2) were performed in dimethylformamide (DMF) under simple heating, affording four hyperbranched poly(methyltriazolylcarboxylate)s (hb-PMTCs) with high molecular weights (Mw up to 2.4 × 104) and regioregularities (up to 83.9%) in good yields. The hb-PMTCs are soluble in common organic solvents, and thermally stable with 5% weight loss temperatures up to 400 °C. They are non-emissive in dilute solution, but become highly emissive in aggregated state, exhibiting aggregation-induced emission characteristics. The polymers can generate fluorescent photopatterns with high resolution, and can work as fluorescent sensors to detect nitroaromatic explosive with high sensitivity.

Spatiotemporal learning and inference in parallel mode is the key advantage for neuromorphic computing, which mimics the human brain architecture. Here, a memtransistor was fabricated with a self-assembled layer of 3-aminopropyltriethoxysilane (APTES) to mimic the synaptic behavior. The aggregates due to the hydrogen bonding between APTES molecules during the self-assembled process could form a defect in the interface. In the memtransistor, the holes could be captured effectively through not only the gate electrode, but also the drain electrode, resulting in controlled carrier concentration in the channel. An obvious hysteresis window was found by applying the operation voltage to the drain electrode. To study the competitive and the cooperative behavior, a multi-terminal memtransistor was prepared, and these synaptic behaviors could be successfully imitated. Finally, an artificial neural network based on the weight updating method was simulated to discriminate the numbers, and the total accuracy reached 96.42%. The results demonstrated that the APTES-based memtransistor had potential applications in synaptic electronics.

Antimonene, which is similar to two-dimensional (2D) phosphorene, has recently gained considerable attention because of its thickness-dependent energy band structure. However, unlike phosphorene, undoped antimonene has an indirect bandgap only at the monolayer limit. In this work, an electrochemical sodium doping strategy was proposed to tune the energy band structure of antimonene. First-principles calculations indicated that a direct bandgap of 0.88 eV formed in 5.55% Na-doped antimonene, while undoped antimonene had an indirect bandgap of 2.38 eV. Optical and electrical measurements provided clear evidence for such a reconstruction of the energy band. We experimentally demonstrated p-type conduction in antimonene quantum dots (QDs)-based field-effect transistors. Furthermore, the induced direct bandgap enabled electric-field control of the surface-enhanced Raman scattering on plasmonic-free antimonene QDs. This allowed for detection of rhodamine 6G with a detection limit down to the sub-femtomolar level. Our study highlights the potential of doped antimonene as an emerging 2D semiconductor.

With the rapid application of artificial intelligence in daily life and work, the traditional von Neumann architecture device faces the limitation of scalability and high energy consumption. These limitations can be overcome by in-memory computing based on analog resistance switch devices, but the resistive switching behavior depends on the formation and rupture of filaments with spatial and temporal variation. According to the filamentary switching mechanisms, conductive filaments play an irreplaceable role in the resistive switching process, and the stochastic filaments are the main cause of nonuniform performances and variation. Therefore, an efficient way to solve these problems is by controlling the filaments. In recent years, researchers have made many efforts to control the filaments, resulting in numerous feasible methods being invented. Herein, departing from the filamentary mechanisms, the strategies of filament control are discussed from the aspects of electrode optimization, switching layer optimization and channel design. Meanwhile, the challenges of promotion in device performance and application in neuromorphic computing and outlook for future research directions are also discussed.

Natural biomaterials are potential candidates for the next generation of green electronics due to their biocompatibility and biodegradability. On the other hand, the application of biocomposite systems in information storage, photoelectrochemical sensing, and biomedicine has further promoted the progress of environmentally benign bioelectronics. Here, we mainly review recent progress in the development of biocomposites in data storage, focusing on the application of biocomposites in resistive random-access memory (RRAM) and field effect transistors (FET) with their device structure, working mechanism, flexibility, transient characteristics. Specifically, we discuss the application of biocomposite-based non-volatile memories for simulating biological synapse. Finally, the application prospect and development potential of biocomposites are presented., Graphical abstract

Inexpensive and flexible organic resistive memory can be easily fabricated, scaled and stacked. Owing to these advantages, organic resistive memory is considered as a very promising technology capable of substituting current inorganic semiconductor-based memory technology. It has attracted a lot of attention from the scientific and engineering communities. In this mini-review, the recent state-of-the-art developments related to organic small molecules for resistive random-access memory (RRAM) have been emphasized. We first describe the general characteristics of RRAM devices, their typical structures, fabrication, classification, and switching mechanisms. Next, we discuss the usage of RRAM devices in next-generation computing. In particular, we discuss the use of organic small molecules and their composites in RRAM with various functionalities. Finally, the current challenges and developing trends of performance improvement for organic small molecule-based RRAM are discussed.

Flexible dielectric polymers and nanocomposites have attracted intensive attention owing to their high electrical breakdown strength, high power density and excellent cycle reliability which are highly demanded for electrostatic energy-storage systems and devices. However, achieving concurrently high discharged energy density (Ue) and discharge efficiency (η) without impairing polymer-endowed mechanical and processing advantages remains a great challenge. In this work, a strategy of doping diminutive CdSe/Cd1−xZnxS quantum dots (QDs) with a dual-ligand structure into a polymer is demonstrated, by which high Ue and η together with largely enhanced mechanical properties are obtained simultaneously. Contrary to conventional sense, a high dielectric constant (K, 17.8 at 1 kHz) is obtained by adding less than 1 volume percent of QDs into the polymer while both the polymer and QDs are intrinsically low-K materials (

Memristor devices have been of great interest over the past decade for the implementation of brain-inspired memory and computing owing to their inherent multistage memory, exquisite structure and higher integration. Herein, a CsPbBr3 QD-based protocol was constructed to exhibit analog memristive characteristics. The field-driven charge trapping/detrapping process was accelerated in the highlighted asymmetric electrode configuration to enable persistent dual direction current modulation, which serves as a basis for synaptic weight variation in the human brain. Significantly, the synaptic functions of long-term potentiation (LTP), long-term depression (LTD) and spike-timing-dependent plasticity (STDP) have been emulated on the device level. Furthermore, light signal-facilitated paired-pulse facilitation (PPF) behavior was validated with in situ atomic force microscopy (AFM) based on electrical techniques. These results may pave a new way to produce memristive devices with advanced implications for future neuromorphic computing.

Aggregation-induced emission (AIE) has attracted increasing attention in recent years in the search for luminescent materials with biomedical and optoelectronic applications. Understanding of its underlying mechanisms is fundamental for the rational design of new AIE materials. In the present work, density functional theory (DFT) calculations were carried out for a set of organic fluorophores which have been recently studied as candidates for color converters in visible light communication. Three of them were (Z)-4-benzylidene-2-methyloxazol-5(4H)-one derivatives combined with an electron-donating moiety of trimethylamine, tetraphenylethene or dimethoxy-tetraphenylethene (TPA-BMO, TPE-BMO or DM-TPE-BMO, respectively). The fourth compound was a diaminomaleonitrile-based Schiff base combined with a dimethylamine moiety (DMA-AM). Our calculations suggested that the restriction of the intramolecular vibration (RIV) mechanism is responsible for the AIE effect observed for TPE-BMO and DM-TPE-BMO in the solid state. On the other hand, the uncommon photophysical behavior reported for DMA-AM (including the AIE phenomenon) in the solid state was related to excitonic coupling effects. Fluorescence spectroscopy experiments confirmed the presence of strongly-coupled DMA-AM aggregates in the solid state. Finally, some electronic properties related to the semiconductor behavior were investigated to explore the potential of applying these fluorophores in light-emitting electronic devices. It must be highlighted that the largest electron-transfer rate constant was calculated for TPE-BMO using the semi-classical Marcus theory, while the largest hole-transfer rate constants were obtained for DMA-AM and TPA-BMO.

The development of efficient multi-component polymerizations from handy monomers to synthesize multifunctional polymers with complicated structures is an attractive but challenging research topic. In this work, a facile, one-pot, three-component polymerization route for in situ generation of polymers with aggregation-induced emission (AIE) characteristics has been developed. Under the catalysis of NiCl2, polycoupling of dihaloarenes, internal diynes, and Grignard reagents proceeded efficiently, generating poly(tetraarylethene)s (PTAEs) with high number average molecular weights (Mn up to 16 800) in high yields (up to 93%) in only three hours. The obtained PTAEs show typical AIE characteristics due to the in situ-generated AIEgen units, tetraphenylethene, in the polymer backbone. Utilizing the AIE property, aggregate-state PTAE could serve as an efficient fluorescent chemosensor for picric acid and Ru3+ with amplified sensitivity, and the quenching constants reached 2.33 × 106 L mol−1 and 6.85 × 104 L mol−1, respectively. Furthermore, the polymer thin films showed modulable refractive indices under UV irradiation in the wide wavelength region of 400–900 nm, presenting great potential in optical fiber applications. Well-resolved 2D fluorescent patterns can also be generated by photo-oxidation of the thin films of PTAEs under UV irradiation through a copper photomask. This work provides another successful example of an in situ generation strategy for functional AIE polymers, broadening the scope of the monomer library.

Memristors that possess massive memory capacity and outstanding processing efficiency concurrently are vitally important to surmount the limitation of Moore's law and traditional Von Neumann bottleneck. Specifically, memristors are capable of integrating various functionalities such as information storage and processing into just one unit to obtain high electrical performance and thereby satisfy the contemporary needs. Here, a multifunctional polymer memristor with combined data storage and processing abilities on the basis of novel solution-processed poly(9,9-dioctyl-9H-fluorene)-alt-1,3-bis(2-ethylhexyl)-(5,7-di(thiophen-2-yl)-4H,8H-benzo[1,2-c:4,5-c′]dithiophene-4,8-dione)-alt-((2,4-pentanedionato)bis(2-(thiophen-2-yl)-pyridine)iridium) (PFTBDD-IrTPy) is demonstrated for the first time. As confirmed by field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) as well as density functional theory (DFT) calculations, the memristive behavior of the multifunctional device is attributed to the synergetic electrochemical metallization and charge transfer effect. Associated with these cation regulating and charge transfer characteristics, our polymer memristor is capable of achieving diverse functionalities comprising multilevel data storage, biological synaptic emulation, Boolean logic function as well as basic arithmetic operations and commutative law of addition, subtraction, multiplication and division. These experimental results will accelerate the development of metal complex polymer based memristors for various electronic applications.

The controlled direct electrical contact (DEC) of an enzyme with the electrode is vital to the design of a bioelectronic device. DNA scaffolds are controllable and programmable but using them to control the DEC of horseradish peroxidase (HRP) with electrodes has not been reported. In this work, porous carbon nanotubes (PCNT), which had excellent electron transfer capability, were synthesized and used as the electrode substrates for the DEC of HRP via target DNA-regulated DNA tweezers (DTs). Target DNA served as fuel can switch the DTs to regulate the distances between the enzyme and PCNT dynamically to control the electrons' transfer efficiency. Our work of direct, unmediated electrical ''wiring'' of enzymes on PCNT controlled by DTs precisely not only expanded the rule set of electrical contact of the enzyme but also had the potential to provide universal platforms to recognize other species through simply altering the related capture. We envision that our platform would inspire the development of artificial unmediated bio-controlled biosensors.

The development of autonomous materials with desired performance and built-in visualizable sensing units is of great academic and industrial significance. Although a wide range of damage indication methods have been reported, the “turn-on” sensing mechanism by damaging events based on microcapsule systems, especially those relying on chemical reactions to elicit a chromogenic response, are still very limited. Herein, a facile and metal-free polymerization route with an interesting reaction-induced coloration effect is demonstrated. Under the catalysis of 1,4-diazabicyclo[2.2.2]octane (DABCO), the polymerizations of difunctional or trifunctional activated alkynes proceed very quickly at 0 oC in air. A series of polymers composed of stereoregular enyne structure (major unit) and divinyl ether structure (minor unit) are obtained. Both the catalyst and monomers are colorless while the polymerized products are deep-colored. This process can be applied for the damage visualization of polymers using the microencapsulation technique. Microcapsules containing the reactive alkyne monomer are prepared and mixed in a DABCO-dispersed polymer film. The mechanical damage of this composite film can be readily visualized once the reaction is initiated from the ruptured microcapsules. Moreover, the newly formed polymer automatically sealed the cracks with an additional protection function.

Two-dimensional MXene has enormous potential for application in industry and academia owing to its surface hydrophilicity and excellent electrochemical properties. However, the application of MXene in optoelectronic memory and logical computing is still facing challenges. In this study, an optoelectronic resistive random access memory (RRAM) based on silver nanoparticles (Ag NPs)@MXene-TiO2 nanosheets (AMT) was prepared through a low-cost and facile hydrothermal oxidation process. The fabricated device exhibited a typical bipolar switching behavior and controllable SET voltage. Furthermore, we successfully demonstrated a 4-bit in-memory digital comparator with AMT RRAMs, which can replace five logic gates in a traditional approach. The AMT-based digital comparator may open the door for future integrated functions and applications in optoelectronic data storage and simplify the complex logic operations.

The development of facile and efficient polymerizations toward functional polymers with unique structures and attractive properties is of great academic and industrial significance. Here we develop a straightforward C–H-activated polyspiroannulation route to in situ generate photoresponsive spiro-polymers with complex structures. The palladium(II)-catalyzed stepwise polyspiroannulations of free naphthols and internal diynes proceed efficiently in dimethylsulfoxide at 120 °C without the constraint of apparent stoichiometric balance in monomers. A series of functional polymers with multisubstituted spiro-segments and absolute molecular weights of up to 39,000 are produced in high yields (up to 99%). The obtained spiro-polymers can be readily fabricated into different well-resolved fluorescent photopatterns with both turn-off and turn-on modes based on their photoinduced fluorescence change. Taking advantage of their photoresponsive refractive index, we successfully apply the polymer thin films in integrated silicon photonics techniques and achieve the permanent modification of resonance wavelengths of microring resonators by UV irradiation., Photoresponsive polymers are receiving great attention due to the increasing demands on smart optical and biological materials. Here, the authors report a C–H-activated polyspiroannulation route to in situ generate photoresponsive spiro-polymers with potential applications in photopatterning and silicon photonics techniques.