Jing Zhang

2D metal-organic framework (MOF) with matching 2D morphology, excellent stability performance, and outstanding optoelectronic performance is grown on the MXene surface through heterojunction-engineering to suppress the direct contact of reactive molecules without affecting the original advantages of MXene. The photoelectric dual gain MXene@MOF heterojunction is confirmed. This work offers a forward-looking strategy for the design of interface materials with excellent photoelectric performance.

Abstract

MXene is widely used in the construction of optoelectronic interfaces due to its excellent properties. However, the hydrophilicity and metastable surface of MXene lead to its oxidation behavior, resulting in the degradation of its various properties, which seriously limits its practical application. In this work, a 2D metal-organic framework (2D MOF) with matching 2D morphology, excellent stability performance, and outstanding optoelectronic performance is grown in situ on the MXene surface through heterojunction engineering to suppress the direct contact between reactive molecules and the inner layer material without affecting the original advantages of MXene. The photoelectric dual gain MXene@MOF heterojunction is confirmed. As a photoelectric material, its properties are highly suitable for the demand of interface sensitization layer materials of surface plasmon resonance (SPR). Therefore, using SPR as a platform for the application of this interface material, the performance of MXene@MOF and its potential mechanism to enhance SPR are analyzed in depth using experiments combined with simulation calculations (FDTD/DFT). Finally, the MXene@MOF/peptides-SPR sensor is constructed for rapid and sensitive detection of the cancer marker exosomes to explore its potential in practical applications. This work offers a forward-looking strategy for the design of interface materials with excellent photoelectric performance.

This paper delves into the integration of memristors with other sensing and controlling systems and offers a comprehensive analysis of the recent research advancements in memristor-based bionic tactile devices. It also outlines future research directions and discusses the potential application prospects of these devices, while proposing feasible solutions to the identified challenges.

Abstract

Bioinspired tactile devices can effectively mimic and reproduce the functions of the human tactile system, presenting significant potential in the field of next-generation wearable electronics. In particular, memristor-based bionic tactile devices have attracted considerable attention due to their exceptional characteristics of high flexibility, low power consumption, and adaptability. These devices provide advanced wearability and high-precision tactile sensing capabilities, thus emerging as an important research area within bioinspired electronics. This paper delves into the integration of memristors with other sensing and controlling systems and offers a comprehensive analysis of the recent research advancements in memristor-based bionic tactile devices. These advancements incorporate artificial nociceptors and flexible electronic skin (e-skin) into the category of bio-inspired sensors equipped with capabilities for sensing, processing, and responding to stimuli, which are expected to catalyze revolutionary changes in human-computer interaction. Finally, this review discusses the challenges faced by memristor-based bionic tactile devices in terms of material selection, structural design, and sensor signal processing for the development of artificial intelligence. Additionally, it also outlines future research directions and application prospects of these devices, while proposing feasible solutions to address the identified challenges.

Nature Photonics, Published online: 27 December 2023; doi:10.1038/s41566-023-01335-5

The progress made in developing light-emitting technologies that are wearable, attachable or implantable is reviewed and potential applications and challenges are discussed.

A 2D polar perovskite showing high-performance self-powered polarized photodetection is acquired. Moreover, its high phase-transition temperature (≈475 K) endows such self-powered polarized photodetection in a large temperature window of device operation. The work will shed bright light on the design of novel polar perovskites for self-powered polarized photodetection in high operating temperature to reduce the external environmental restriction.

Abstract

Polarization photodetection taking advantage of the anisotropy of 2D materials shines brilliantly in optoelectronic fields owing to differentiating optical information. However, the previously reported polarization detections are mostly dependent on external power sources, which is not conducive to device integration and energy conservation. Herein, a 2D polar perovskite (CBA)₂CsPb₂Br₇ (CCPB, CBA = 4-chlorobenzyllamine) has been successfully synthesized, which shows anticipated bulk photovoltaic effect (BPVE) with an open-circuited photovoltage up to ≈0.2 V. Devices based on CCPB monomorph fulfill a fascinating self-powered polarized photodetection with a large polarization ratio of 2.7 at room temperature. Moreover, CCPB features a high phase-transition temperature (≈475 K) which prompts such self-powered polarized photodetection in a large temperature window of device operation, since BPVE generated by spontaneous polarization can only exist in the polar structure prior to the phase transition. Further computational investigation reveals the introduction of CBA⁺ with a large dipole moment contributes to quite large polarization (17.5 µC cm⁻²) and further super high phase transition temperature of CCPB. This study will promote the application of 2D perovskite materials for self-powered polarized photodetection in high-temperature conditions.

Coupling of ferroelectricity and optical properties has emerged as a captivating aspect of material research. This work demonstrates that (3AMP)PbI₄ (3AMP = 3-(aminomethyl)pyridinium), a 2D Dion–Jacobson perovskite, not only boasts a remarkable spontaneous polarization, but also displays unique thermochromism. These findings will inspire further exploration and application of multifunctional perovskites.

Abstract

2D organic–inorganic hybrid perovskites (OIHPs) have become one of the hottest research topics due to their excellent environmental stability and unique optoelectronic properties. Recently, the ferroelectricity and thermochromism of 2D OIHPs have attracted increasing interests. Integrating ferroelectricity and thermochromism into perovskites can significantly promote the development of multichannel intelligent devices. Here, a novel 2D Dion-Jacobson OIHP of the formula (3AMP)PbI₄ (where 3AMP is 3-(aminomethyl)pyridinium) is reported, which has a remarkable spontaneous polarization value (Ps) of 15.6 µC cm⁻² and interesting thermochromism. As far it is known, such a large Ps value is the highest for 2D OIHPs recorded so far. These findings will inspire further exploration and application of multifunctional perovskites.

Somatic cells contributed by donors (human, rodent, primate) can be reprogrammed into induced pluripotent stem cells or neurons, and brain tissue/slice directly extracted from donors can be used as culture on a chip. The entire stage of neural development can be demonstrated on a chip.

Abstract

As an ideal in vitro model, brain-on-chip (BoC) is an important tool to comprehensively elucidate brain characteristics. However, the in vitro model for the definition scope of BoC has not been universally recognized. In this review, BoC is divided into brain cells-on-a- chip, brain slices-on-a-chip, and brain organoids-on-a-chip according to the type of culture on the chip. Although these three microfluidic BoCs are constructed in different ways, they all use microfluidic chips as carrier tools. This method can better meet the needs of maintaining high culture activity on a chip for a long time. Moreover, BoC has successfully integrated cell biology, the biological material platform technology of microenvironment on a chip, manufacturing technology, online detection technology on a chip, and so on, enabling the chip to present structural diversity and high compatibility to meet different experimental needs and expand the scope of applications. Here, the relevant core technologies, challenges, and future development trends of BoC are summarized.

This review introduces the cornerstone principles of electrospinning and solar fuels as well as various roles of electrospun nanofibers in developing the efficiency of photocatalytic systems. Beyond that, in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS), as a novel technique to do mechanism research on electrospun nanofibers based photocatalysts, is also systemically discussed.

Abstract

Producing solar fuels over photocatalysts under light irradiation is a considerable way to alleviate energy crises and environmental pollution. To develop the yields of solar fuels, photocatalysts with broad light absorption, fast charge carrier migration, and abundant reaction sites need to be designed. Electrospun 1D nanofibers with large specific areas and high porosity have been widely used in the efficient production of solar fuels. Nevertheless, it is challenging to do in-depth mechanism research on electrospun nanofiber-based photocatalysts since there are multiple charge transfer routes and various reaction sites in these systems. Here, the basic principles of electrospinning and photocatalysis are systemically discussed. Then, the different roles of electrospun nanofibers played in recent research to boost photocatalytic efficiency are highlighted. It is noteworthy that the working principles and main advantages of in situ irradiated photoelectron spectroscopy (ISI-XPS), a new technique to investigate migration routes of charge carriers and identify active sites in electrospun nanofibers based photocatalysts, are summarized for the first time. At last, a brief summary on the future orientation of photocatalysts based on electrospun nanofibers as well as the perspectives on the development of the ISI-XPS technique are also provided.

This study introduces a cross-wired crossbar array (cwCBA) using a Pt/Ta₂O₅/HfO₂/TiN memristor for precise physical graph representation (PGR) and dynamic node state control. The cwCBA, with enhanced PGR precision, successfully executes a dynamic path-finding algorithm with significantly lower processing complexity and analyzes complex protein–protein interaction networks, showing notable improvements in predictive accuracy over conventional methods.

Abstract

Graphs adequately represent the enormous interconnections among numerous entities in big data, incurring high computational costs in analyzing them with conventional hardware. Physical graph representation (PGR) is an approach that replicates the graph within a physical system, allowing for efficient analysis. This study introduces a cross-wired crossbar array (cwCBA), uniquely connecting diagonal and non-diagonal components in a CBA by a cross-wiring process. The cross-wired diagonal cells enable cwCBA to achieve precise PGR and dynamic node state control. For this purpose, a cwCBA is fabricated using Pt/Ta₂O₅/HfO₂/TiN (PTHT) memristor with high on/off and self-rectifying characteristics. The structural and device benefits of PTHT cwCBA for enhanced PGR precision are highlighted, and the practical efficacy is demonstrated for two applications. First, it executes a dynamic path-finding algorithm, identifying the shortest paths in a dynamic graph. PTHT cwCBA shows a more accurate inferred distance and ≈1/3800 lower processing complexity than the conventional method. Second, it analyzes the protein–protein interaction (PPI) networks containing self-interacting proteins, which possess intricate characteristics compared to typical graphs. The PPI prediction results exhibit an average of 30.5% and 21.3% improvement in area under the curve and F1-score, respectively, compared to existing algorithms.

Organic Field-Effect Transistors

In article number 2304736, Boyu Peng, Hanying Li, and co-workers utilize single-domain molecular monolayer crystals as the active channel to largely enhance the uniformity of organic field-effect transistors. The herringbone-packed white bricks represent the densely packed molecules in the molecular monolayer crystals. The whole brick layer is curved, indicating the potential of such material for further flexible electronic applications.

Both wavelength-tunable coloration and light intensity-tunable photoluminescence are independently and reliably manipulated in the thin polymer-based film. A rewritable dual-responsive encryption display that has the benefit of direct and intuitive identification of encrypted information by the human eye is presented, enabling high information security and anti-counterfeiting.

Abstract

Optical encryption using coloration and photoluminescent (PL) materials can provide highly secure data protection with direct and intuitive identification of encrypted information. Encryption capable of independently controlling wavelength-tunable coloration as well as variable light intensity PL is not adequately demonstrated yet. Herein, a rewritable PL and structural color (SC) display suitable for dual-responsive optical encryption developed with a stimuli-responsive SC of a block copolymer (BCP) photonic crystal (PC) with alternating in-plane lamellae, of which a variety of 3D and 2D perovskite nanocrystals is preferentially self-assembled with characteristic PL, is presented. The SC of a BCP PC is controlled in the visible range with different perovskite precursor doping times. The perovskite nanocrystals developed in the BCP PC are highly luminescent, with a PL quantum yield of ≈33.7%, yielding environmentally stable SC and PL dual-mode displays. The independently programmed SC and PL information is erasable and rewritable. Dual-responsive optical encryption is demonstrated, in which true Morse code information is deciphered only when the information encoded by SCs is properly combined with PL information. Numerous combinations of SC and PL realize high security level of data anticounterfeiting. This dual-mode encryption display offers novel optical encryption with high information security and anti-counterfeiting.

The evolution of local structural distortion and lattice dynamics across the charge density wave transition of GdTe₃ is studied by synchrotron X-ray pair distribution function analysis and thermoelectric properties. A large anisotropic lattice thermal conductivity is observed in GdTe₃ due to its natural heterostructure of charged and van der Waals layers, strong electron-phonon coupling, and large lattice anharmonicity.

Abstract

Structural mosaic of rare-earth tri-tellurides (RTe₃) inlaid with non-classical structural motifs like the 2D−polytelluride square nets has attracted immense attention owing to their enigmatic chemical bonding, unconventional structure, and harboring charge density wave (CDW) ground states. GdTe₃, an archetypal RTe₃, is a natural heterostructure of charged and van der Waals (vdW) layers, formed by intercalating vdW gap separated 2D square telluride nets [(Te₂)⁻]_n between the charged double corrugated slabs of n[GdTe]⁺. Here, we have investigated the evolution of structural distortions along with the electrical and thermal transport properties of GdTe₃ across its CDW transition through X-ray pair distribution function analysis, thermal conductivity measurements, Raman spectroscopy and first principles theoretical calculations. The results reveal that the unusual structure of GdTe₃ engenders a large anisotropic lattice thermal conductivity by concomitantly hampering the phonon propagation along parallel to the spark plasma sintering (SPS) pressing direction via chemical bonding hierarchy while facilitating phonon propagation along perpendicular to the SPS pressing direction through the metallic Te sheets and phason channel. The low lattice thermal conductivity is attributed to the strong vibrational anharmonicity caused by CDW-induced concerted local lattice distortions of both Gd–Te slab and Te square net, and the robust electron–phonon coupling.

The direct laser patterning (DLP) technology is proposed to construct flexible planar aqueous zinc-manganese dioxide microbatteries (MBs), which not only gets rid of the complicated manufacturing procedures and time-consuming post-treatment processes of traditional methods, but also helps the planar MBs access high areal capacity and energy density, surpassing Li/Na-based MBs and most available aqueous Zn-based MBs.

Abstract

Miniature batteries with programmable shape and scalable functions can provide new opportunities in the design of highly compatible integrated circuits and flexible microelectronics. However, achieving these energy supply devices requires the precise formation of highly active electrode materials in a high-resolution patterned area using appropriate construction protocols. Here, shape-customizable zinc-based microbatteries (MBs) using an all-direct laser patterning (DLP) technique is demonstrated. Unlike conventional processing approaches, the DLP with high spatial-resolution can not only enable template-free and efficient arbitrary customizable fabrication of geometry patterns, such as circular, papercut, tropical fish, house shapes, among others, but also spontaneously create oxygen vacancies within micro-electrode materials that are beneficial to increasing electrochemical active sites. The resultant Zn//MnO₂ MBs deliver a high areal capacity of 0.57 mAh cm⁻² and an energy density of 0.75 mWh cm⁻², surpassing most available aqueous Zn-based MBs and Li/Na-based MBs. This strategy can also be extended to other battery systems, such as Zn//Co and Zn//Ag MBs. More importantly, these micro-batteries are easily integrated into on-chip electronic systems as built-in power supply to be highly compatible with multiple sensing functionalities, which showcase accurately monitoring wrist bending, pulse beating, temperature, and moisture signals in humans.

The IoT's growth fuels research on MXene integration into textiles. The automated yarn dip coater exceeds manual methods, providing lower resistance, superior uniformity, faster speed, and reduced MXene consumption across multiple yarns. It swiftly optimizes coatings for specific applications, demonstrated on a braided Kevlar yarn for Joule heating and strain sensing in composites.

Abstract

The rise of the Internet of Things has spurred extensive research on integrating conductive materials into textiles to turn them into sensors, antennas, energy storage devices, and heaters. MXenes, owing to their high electrical conductivity and solution processability, offer an efficient way to add conductivity and electronic functions to textiles through simple dip coating. However, manual development of MXene-coated textiles restricts their quality, quantity, and variety. Here, a versatile automated yarn dip coater tailored for producing continuously high-quality MXene-coated yarns and conducted the most comprehensive MXene-yarn dip coating study to date is developed. Compared to manual methods, the automated coater provides lower resistance, superior uniformity, faster speed, and reduced MXene consumption. It also enables rapid coating parameter optimization, resulting in a thin Ti₃C₂ coating uniform over a 1 km length on a braided Kevlar yarn while preserving its excellent mechanical properties (over 800 MPa) and adding Joule heating and damage sensing to composites reinforced by the yarns. By dip-coating five different yarns of varying materials, diameters, structures, and chemistries, new insights into MXene-yarn interactions are gained. Thus, the automated dip coating presents ample opportunities for scalable integration of MXenes into a wide range of yarns for diverse functions and applications.

Dual-Microcavity Technology

In article number 2305528, Kwan Hyun Cho, Yun Seon Do, and co-workers present a dual-microcavity structure that consists of the same thickness of the R/G/B subpixels. This results in reducing the complexity of both the design and fabrication. Also, the dual-microcavity structure provides higher efficiency and high color purity in the R/G/B, simultaneously. This technology could be applied in various fields handling electroluminescent devices such as OLEDs, QLEDs, and micro-LEDs.

The mechanical properties, failures, flexible substrates, each functional layer, and recent advancement of flexible perovskite light-emitting diodes (LEDs) are summarized. A brief outlook on the challenges faced by flexible perovskite LEDs and their possible future development is also provided.

Abstract

Future displays need to be stretchable, bendable, and wearable to match consumers’ needs for convenience, portable equipment, and real-time information display. The development of flexible light source components, like flexible light-emitting diodes (LEDs), is urgently required to fulfill these needs. Metal halide perovskites, known for their excellent optoelectronic properties and ductility, are considered the most promising light-emitting materials for high-definition displays, and their outstanding advantage is that the metal halide perovskites would be achieved by solution process under low temperature (<150 °C), which is especially good for the flexible organic substrates to maintain high conductivity during fabrication of flexible LEDs. In recent years, flexible perovskite LEDs have made significant progress, but still face a great deal of difficulties, obstacles, and great challenges. Herein, the mechanical properties of perovskite materials are examined and the failures for perovskite-based flexible optoelectronic devices under strain are discussed. The authors then focus on optimizing each functional layer and the recent advancement in flexible perovskite LEDs is summarized. Finally, a brief outlook on the challenges faced by flexible perovskite LEDs and their possible future development is provided.

Nature Materials, Published online: 22 December 2023; doi:10.1038/s41563-023-01776-x

A fast-switching thermal transistor

The antimony selenide (Sb₂Se₃) films achieve the transition from (hk0) to (hk1) plane on the contact substrate of digenite (Cu₉S₅) films. The ordered arrangement of chained Sb₄Se₆ appears as (211), (221), (101), (151), (301), and (410) crystal plane by post-annealing treatment. The different crystal growth in the Sb₂Se₃ films leads to flake- and flower-like morphologies on the surface.

Abstract

Antimony selenide (Sb₂Se₃) is a promising semiconductor for photodetector applications due to its unique photovoltaic properties. Achieving optimal carrier transport in (001)-Sb₂Se₃ by the material of contacting substrate requires in-depth study. In this paper, the induced growth of Sb₂Se₃ films from (hk0) to (hk1) planes is achieved on digenite (Cu₉S₅) films by post-annealing treatment. The flake-like and flower-like morphologies on the surface of Sb₂Se₃ films are caused by different thicknesses of the Cu₉S₅ films, which are related to the (hk0) and (hk1) planes of Sb₂Se₃ surface. The epitaxial growth of Sb₂Se₃ films on (105)-Cu₉S₅ surfaces exhibits thickness dependence. The results inform research into the controlled induced growth of low-dimensional materials. The device of Sb₂Se₃/Cu₉S₅/Si has good broadband response (visible to near-infrared), self-powered characteristics, and stability. As the crystalline quality of the Sb₂Se₃ film increases along the (hk1) plane, the carrier transport is enhanced correspondingly. Under the 980 nm light irradiation, the device has an excellent switching ratio of 2 × 10⁴ at 0 bias, with responsivity, detectivity, and response time up to 17 µA W⁻¹, 1.48 × 10⁷ Jones, and 355/490 µs, respectively. This suggests that Sb₂Se₃ is suitable for self-powered photodetectors and related optical and optoelectronic devices.

Nature Electronics, Published online: 21 December 2023; doi:10.1038/s41928-023-01082-z

This Review examines the development of neuromorphic hardware systems based on halide perovskites, considering how devices based on these materials can serve as synapses and neurons, and can be used in neuromorphic computing networks.

Advanced Functional Materials, Volume 34, Issue 15, April 10, 2024.

Host-guest thermally activated delayed fluorescence nanoparticles are assembled with cell-penetrating peptides for fast biological imaging. With highly efficient long-lived fluorescence, real-time in vivo time-resolved luminescence imaging of zebrafish activity is achieved on a chopper-based wide-field microscope, avoiding the strong autofluorescence from organisms.

Abstract

Thermally activated delayed fluorescence (TADF) nanoparticles are used importantly in time-resolved luminescence imaging for eliminating the background signals from scattering and short-lived autofluorescence. However, TADF nanoparticles are seldom used for real-time time-resolved luminescence imaging, due to their limited luminescence efficiency and lifetimes. To detect delayed fluorescence, multiple excitation cycles with adequate delay times are usually required, leading to long detecting durations and low imaging speed. Herein, highly efficient red TADF nanoparticles are developed through doping a guest molecule, TPAAQ (2,6-bis[4-(diphenylamino) phenyl] anthraquinone), in a host (4,4′-bis(carbazol-9-yl)biphenyl, CBP) matrix. With a low doping concentration, the nanoparticles can exhibit obvious TADF with luminescence lifetimes over 0.1 ms and photoluminescence quantum yield up to 35%. A cell-penetrating peptide is used together with the amphiphilic compound for assembling nanoparticles, which can easily penetrate cells and greatly increase the TADF signals for luminescence lifetime imaging. Thanks to the long-lived and highly efficient TADF, real-time in vivo time-gated luminescence imaging of zebrafish is realized on a chopper-based wide-field microscope. This low-cost time-resolved luminescence imaging method showed a great potential for real-time detection of life activities in many organisms with high autofluorescence.

This review focuses on the strategies to access and manage sweat for non-invasive and long-term biomarker monitoring in wearable prototypes. The comprehensive information provided here will help researchers to develop more robust and advanced versions of sweat-based wearables that would strengthen personalized healthcare monitoring.

Abstract

Sweat is an important biofluid presents in the body since it regulates the internal body temperature, and it is relatively easy to access on the skin unlike other biofluids and contains several biomarkers that are also present in the blood. Although sweat sensing devices have recently displayed tremendous progress, most of the emerging devices primarily focus on the sensor development, integration with electronics, wearability, and data from in vitro studies and short-term on-body trials during exercise. To further the advances in sweat sensing technology, this review aims to present a comprehensive report on the approaches to access and manage sweat from the skin toward improved sweat collection and sensing. It is begun by delineating the sweat secretion mechanism through the skin, and the historical perspective of sweat, followed by a detailed discussion on the mechanisms governing sweat generation and management on the skin. It is concluded by presenting the advanced applications of sweat sensing, supported by a discussion of robust, extended-operation epidermal wearable devices aiming to strengthen personalized healthcare monitoring systems.

Nature, Published online: 20 December 2023; doi:10.1038/d41586-023-03791-z

A transistor made from atomically thin materials mimics the way in which connections between neurons are strengthened by activity. Two perspectives reveal why physicists and neuroscientists share equal enthusiasm for this feat of engineering.

Nature, Published online: 20 December 2023; doi:10.1038/s41586-023-06791-1

We report the experimental realization and room-temperature operation of a low-power (20 pW) moiré synaptic transistor based on an asymmetric bilayer graphene/hexagonal boron nitride moiré heterostructure.

Stretchable Electronics

Eutectic gallium indium (EGaIn) is an attractive conductor for stretchable electronics but its high surface energy makes sub-micrometer patterning challenging. In article number 2305967, Francisco Molina-Lopez, Jan Fransaer, and co-workers overcome this limitation by electrodeposition, a “bottom-up” approach that benefits from the resolution of mature nanofabrication methods. A record-high integration of EGaIn lines of 300 nm half-pitch is achieved. Moreover, vertical integration is enabled, leading to omnidirectionally-stretchable 3D electronics.