Abstract: It is of great significance to develop clean and new energy sources with high-efficient energy storage technologies, due to the excessive use of fossil energy that has caused severe environmental damage. There is great interest in exploring advanced rechargeable lithium batteries with desirable energy and power capabilities for applications in portable electronics, smart grids, and electric vehicles. In practice, high-capacity and low-cost electrode materials play an important role in sustaining the progresses in lithium-ion batteries. This review aims at giving an account of recent advances on the emerging high-capacity electrode materials and summarizing key barriers and corresponding strategies for the practical viability of these electrode materials. Effective approaches to enhance energy density of lithium-ion batteries are to increase the capacity of electrode materials and the output operation voltage. On account of major bottlenecks of the power lithium-ion battery, authors come up with the concept of integrated battery systems, which will be a promising future for high-energy lithium-ion batteries to improve energy density and alleviate anxiety of electric vehicles.

Abstract: Graphene oxide (GO) was initially developed to emulate graphene, but it was soon recognized as a functional material in its own right, addressing an application space that is not accessible to graphene and other carbon materials. Over the past decade, research on GO has made tremendous advances in material synthesis and property tailoring. These, in turn, have led to rapid progress in GO-based photonics, electronics and optoelectronics, paving the way for technological breakthroughs with exceptional performance. In this Review, we provide an overview of the optical, electrical and optoelectronic properties of GO and reduced GO on the basis of their chemical structures and fabrication approaches, together with their applications in key technologies such as solar energy harvesting, energy storage, medical diagnosis, image display and optical communications. We also discuss the challenges of this field, together with exciting opportunities for future technological advances. As the most common derivative of graphene, graphene oxide has emerged as a new frontier material with tremendous applications to photonics, electronics and optoelectronics in the past decade. This Review highlights the state of the art and future prospects for this fast-growing field.

Abstract: Organic electrochemical transistors (OECTs) and OECT-based circuitry offer great potential in bioelectronics, wearable electronics and artificial neuromorphic electronics because of their exceptionally low driving voltages (<1 V), low power consumption (<1 µW), high transconductances (>10 mS) and biocompatibility1-5. However, the successful realization of critical complementary logic OECTs is currently limited by temporal and/or operational instability, slow redox processes and/or switching, incompatibility with high-density monolithic integration and inferior n-type OECT performance6-8. Here we demonstrate p- and n-type vertical OECTs with balanced and ultra-high performance by blending redox-active semiconducting polymers with a redox-inactive photocurable and/or photopatternable polymer to form an ion-permeable semiconducting channel, implemented in a simple, scalable vertical architecture that has a dense, impermeable top contact. Footprint current densities exceeding 1 kA cm-2 at less than ±0.7 V, transconductances of 0.2-0.4 S, short transient times of less than 1 ms and ultra-stable switching (>50,000 cycles) are achieved in, to our knowledge, the first vertically stacked complementary vertical OECT logic circuits. This architecture opens many possibilities for fundamental studies of organic semiconductor redox chemistry and physics in nanoscopically confined spaces, without macroscopic electrolyte contact, as well as wearable and implantable device applications.

Abstract: This article provides an introduction to Electromagnetic Compatibility (EMC) for power electronics. It provides a description of the EMC requirements, EMC theory, EMC measurements, EMC mitigation and the international standards that are applied. Only a brief description is provided in each case with cited references provided for more detailed explanations. This is article introduces Electromagnetic Compatibility for power electronics. It first defines the requirements for EMC in terms of legal and technical requirements and the usual accepted routes for meeting the requirements. The EMC technical terminology is then elaborated. There are then articles on the theory of interference and the main mitigation techniques including the use of filters. Practical considerations are also outlined including EMC measurement techniques. In all cases suitable references are given where more details can be found.

Abstract: The emergence of plastic electronics satisfies the increasing demand for flexible electronics. However, it has caused severe ecological problems. Flexible electronics based on natural materials are increasing to hopefully realize the “green” and eco‐friendly concept. Herein, recent advances in the design and fabrication of green flexible electronics are reviewed. First, this review comprehensively introduces various natural materials and derivatives, focusing particularly on fibroin and silk, wood and paper, plants, and biomass. Second, fabrication techniques for modifying natural materials, including physical and chemical methods, are presented, after which their merits and demerits are thoroughly discussed. Green flexible electronics based on natural materials, comprising electrical wires/electrodes, antennas, thermal management devices, transistors, memristors, sensors, energy‐harvesting devices, energy‐storage devices, displays, actuators, electromagnetic shielding, and integration systems, are described in detail. Finally, perspectives on the existing challenges and opportunities to employ natural materials in green flexible electronics are presented.

Abstract: Gallium nitride (GaN) devices are revolutionarily advancing the efficiency, frequency, and form factor of power electronics. However, the material composition, architecture and physics of many GaN devices are significantly different from silicon and silicon carbide devices. These distinctions result in many unique stability, reliability and robustness issues facing GaN power devices. This paper reviews the current understanding of these issues, particularly those related to dynamic switching, and their impacts on system performance. Instead of delving into reliability physics, this paper intends to provide power electronics engineers the necessary information for deploying GaN devices in existing and emerging applications, as well as provide references for the qualification evaluations of GaN power devices. The issues covered in this paper include the dynamic instability of device parameters (e.g., on-resistance, threshold voltage, output capacitance), the device robustness in avalanche, overvoltage and short-circuit conditions, the device's switching reliability and lifetime, as well as the device's ruggedness under radiation and extreme (cryogenic and elevated) temperatures. Knowledge gaps and immediate research opportunities in the relevant fields are also discussed.

Abstract: Flexible conductive materials with intrinsic structural characteristics are currently in the spotlight of both fundamental science and advanced technological applications due to their functional preponderances such as the remarkable conductivity, excellent mechanical properties, and tunable physical and chemical properties, and so on. Typically, conductive hydrogel fibers (CHFs) are promising candidates owing to their unique characteristics including light weight, high length‐to‐diameter ratio, high deformability, and so on. Herein, a comprehensive overview of the cutting‐edge advances the CHFs involving the architectural features, function characteristics, fabrication strategies, applications, and perspectives in flexible electronics are provided. The fundamental design principles and fabrication strategies are systematically introduced including the discontinuous fabrication (the capillary polymerization and the draw spinning) and the continuous fabrication (the wet spinning, the microfluidic spinning, 3D printing, and the electrospinning). In addition, their potential applications are crucially emphasized such as flexible energy harvesting devices, flexible energy storage devices, flexible smart sensors, and flexible biomedical electronics. This review concludes with a perspective on the challenges and opportunities of such attractive CHFs, allowing for better understanding of the fundamentals and the development of advanced conductive hydrogel materials.

Abstract: Due to their potential applications in physiological monitoring, diagnosis, human prosthetics, haptic perception, and human-machine interaction, flexible tactile sensors have attracted wide research interest in recent years. Thanks to the advances in material engineering, high performance flexible tactile sensors have been obtained. Among the representative pressure sensing materials, 2D layered nanomaterials have many properties that are superior to those of bulk nanomaterials and are more suitable for high performance flexible sensors. As a class of 2D inorganic compounds in materials science, MXene has excellent electrical, mechanical, and biological compatibility. MXene-based composites have proven to be promising candidates for flexible tactile sensors due to their excellent stretchability and metallic conductivity. Therefore, great efforts have been devoted to the development of MXene-based composites for flexible sensor applications. In this paper, the controllable preparation and characterization of MXene are introduced. Then, the recent progresses on fabrication strategies, operating mechanisms, and device performance of MXene composite-based flexible tactile sensors, including flexible piezoresistive sensors, capacitive sensors, piezoelectric sensors, triboelectric sensors are reviewed. After that, the applications of MXene material-based flexible electronics in human motion monitoring, healthcare, prosthetics, and artificial intelligence are discussed. Finally, the challenges and perspectives for MXene-based tactile sensors are summarized.

Abstract: Hydrogels have emerged as promising materials for flexible electronics due to their unique properties, such as high water content, softness, and biocompatibility. In this perspective, we provide an overview of the development of hydrogels for flexible electronics, with a focus on three key aspects: mechanical properties, interfacial adhesion, and conductivity. We discuss the principles of designing high-performance hydrogels and present representative examples of their potential applications in the field of flexible electronics for healthcare. Despite significant progress, several challenges remain, including improving the antifatigue capability, enhancing interfacial adhesion, and balancing water content in wet environments. Additionally, we highlight the importance of considering the hydrogel-cell interactions and the dynamic properties of hydrogels in future research. Looking ahead, the future of hydrogels in flexible electronics is promising, with exciting opportunities on the horizon, but continued investment in research and development is necessary to overcome the remaining challenges.

Abstract: Given the rise in the popularity of wearable electronics that are able to deform into desirable configurations while maintaining electrochemical functionality, stretchable and flexible (hybrid) supercapacitors (SCs) have become increasingly of interest as innovative energy storage devices. Their outstanding power density, long lifetime with low capacitance loss, and appropriate energy density, in particular in hybrid cases make them ideal candidates for flexible electronics. The aim of this review paper is to provide an in-depth discussion of these stretchable and flexible SCs ranging from fabrication to electro-mechanical properties. This review paper begins with a short overview of the fundamentals of charge storage mechanisms and different types of multivalent metal-ion hybrid SCs. The research methods leading up to the current state of these stretchable and flexible SCs are then presented. This is followed by an in-depth presentation of the challenges associated with the fabrication methods for different configurations. Proposed novel strategies to maximize the elastic and electrochemical properties of stretchable/flexible or quasi-solid-state SCs are classified and the pros and cons associated with each are shown. The advances in mechanical properties and the expected advancements for the future of these SCs are discussed in the last section.

Abstract: Tactile sensors with high spatial resolution are crucial to manufacture large scale flexible electronics, and low crosstalk sensor array combined with advanced data analysis is beneficial to improve detection accuracy. Here, we demonstrated the photo-reticulated strain localization films (prslPDMS) to prepare the ultralow crosstalk sensor array, which form a micro-cage structure to reduce the pixel deformation overflow by 90.3% compared to that of conventional flexible electronics. It is worth noting that prslPDMS acts as an adhesion layer and provide spacer for pressure sensing. Hence, the sensor achieves the sufficient pressure resolution to detect 1 g weight even in bending condition, and it could monitor human pulse under different states or analyze the grasping postures. Experiments show that the sensor array acquires clear pressure imaging and ultralow crosstalk (33.41 dB) without complicated data processing, indicating that it has a broad application prospect in precise tactile detection.

Abstract: Self-healing soft electronic and robotic devices can, like human skin, recover autonomously from damage. While current devices use a single type of dynamic polymer for all functional layers to ensure strong interlayer adhesion, this approach requires manual layer alignment. In this study, we used two dynamic polymers, which have immiscible backbones but identical dynamic bonds, to maintain interlayer adhesion while enabling autonomous realignment during healing. These dynamic polymers exhibit a weakly interpenetrating and adhesive interface, whose width is tunable. When multilayered polymer films are misaligned after damage, these structures autonomously realign during healing to minimize interfacial free energy. We fabricated devices with conductive, dielectric, and magnetic particles that functionally heal after damage, enabling thin-film pressure sensors, magnetically assembled soft robots, and underwater circuit assembly. Description Editor’s summary One advantage of using soft materials for robotic devices is that there is greater scope for self-healing, but a challenge for multilayer devices is to ensure realignment after damage. Cooper et al. present a method for healing multilayered and functional polymer materials by showing how a combination of dynamic hydrogen-bonding interactions and phase separation between different polymeric building blocks can be leveraged to achieve simultaneous autonomous realignment and healing of multilayered polymer films. This approach can restore both the mechanical and functional properties of complex polymer composites and even enables underwater self-assembly. —Marc S. Lavine Soft electronic devices and robots heal themselves without manual intervention.

Abstract: Among the increasingly popular miniature and flexible smart electronics, two-dimensional materials show great potential in the development of flexible electronics owing to their layered structures and outstanding electrical properties. MXenes have attracted much attention in flexible electronics owing to their excellent hydrophilicity and metallic conductivity. However, their limited interlayer spacing and tendency for self-stacking lead to limited changes in electron channels under external pressure, making it difficult to exploit their excellent surface metal conductivity. We propose a strategy for rapid gas foaming to construct interlayer tunable MXene aerogels. MXene aerogels with rich interlayer network structures generate maximized electron channels under pressure, facilitating the effective utilization of the surface metal properties of MXene; this forms a self-healable flexible pressure sensor with excellent sensing properties such as high sensitivity (1,799.5 kPa-1), fast response time (11 ms), and good cycling stability (>25,000 cycles). This pressure sensor has applications in human body detection, human-computer interaction, self-healing, remote monitoring, and pressure distribution identification. The maximized electron channel design provides a simple, efficient, and scalable method to effectively exploit the excellent surface metal conduction of 2D materials.

Abstract: Advanced elastomers are increasingly used in emerging areas, for example, flexible electronics and devices, and these real‐world applications often require elastomers to be stretchable, tough and fire safe. However, to date there are few successes in achieving such a performance portfolio due to their different governing mechanisms. Herein, a stretchable, supertough, and self‐extinguishing polyurethane elastomers by introducing dynamic π–π stacking motifs and phosphorus‐containing moieties are reported. The resultant elastomer shows a large break strain of ≈2260% and a record‐high toughness (ca. 460 MJ m−3), which arises from its dynamic microphase‐separated microstructure resulting in increased entropic elasticity, and strain‐hardening at large strains. The elastomer also exhibits a self‐extinguishing ability thanks to the presence of both phosphorus‐containing units and π–π stacking interactions. Its promising applications as a reliable yet recyclable substrate for strain sensors are demonstrated. The work will help to expedite next‐generation sustainable advanced elastomers for flexible electronics and devices applications.

Abstract: As an outstanding representative of layered materials, molybdenum disulfide (MoS2) has excellent physical properties, such as high carrier mobility, stability, and abundance on earth. Moreover, its reasonable band gap and microelectronic compatible fabrication characteristics makes it the most promising candidate in future advanced integrated circuits such as logical electronics, flexible electronics, and focal-plane photodetector. However, to realize the all-aspects application of MoS2, the research on obtaining high-quality and large-area films need to be continuously explored to promote its industrialization. Although the MoS2 grain size has already improved from several micrometers to sub-millimeters, the high-quality growth of wafer-scale MoS2 is still of great challenge. Herein, this review mainly focuses on the evolution of MoS2 by including chemical vapor deposition, metal-organic chemical vapor deposition, physical vapor deposition, and thermal conversion technology methods. The state-of-the-art research on the growth and optimization mechanism, including nucleation, orientation, grain, and defect engineering, is systematically summarized. Then, this review summarizes the wafer-scale application of MoS2 in a transistor, inverter, electronics, and photodetectors. Finally, the current challenges and future perspectives are outlined for the wafer-scale growth and application of MoS2.

Abstract: Fibers, originating from nature and mastered by human, have woven their way throughout the entire history of human civilization. Recent developments in semiconducting polymer materials have further endowed fibers and textiles with various electronic functions, which are attractive in applications such as information interfacing, personalized medicine, and clean energy. Owing to their ability to be easily integrated into daily life, soft fiber electronics based on semiconducting polymers have gained popularity recently for wearable and implantable applications. Herein, we present a review of the previous and current progress in semiconducting polymer-based fiber electronics, particularly focusing on smart-wearable and implantable areas. First, we provide a brief overview of semiconducting polymers from the viewpoint of materials based on the basic concepts and functionality requirements of different devices. Then we analyze the existing applications and associated devices such as information interfaces, healthcare and medicine, and energy conversion and storage. The working principle and performance of semiconducting polymer-based fiber devices are summarized. Furthermore, we focus on the fabrication techniques of fiber devices. Based on the continuous fabrication of one-dimensional fiber and yarn, we introduce two- and three-dimensional fabric fabricating methods. Finally, we review challenges and relevant perspectives and potential solutions to address the related problems.

Abstract: The rapid rise of triboelectric nanogenerators (TENGs), which are emerging energy conversion devices in advanced electronics and wearable sensing systems, has elevated the interest in high‐performance and multifunctional triboelectric materials. Among them, cellulosic materials, affording high efficiency, biodegradability, and customizability, are becoming a new front‐runner. The inherently low dielectric constant limits the increase in the surface charge density. However, owing to its unique structure and excellent processability, cellulose shows great potential for dielectric modulation, providing a strong impetus for its advanced applications in the era of Internet of Things and artificial intelligence. This review aims to provide comprehensive insights into the fabrication of dielectric‐enhanced cellulosic triboelectric materials via dielectric modulation. The exceptional advantages and research progress in cellulosic materials are highlighted. The effects of the dielectric constant, polarization, and percolation threshold on the charge density are systematically investigated, providing a theoretical basis for cellulose dielectric modulation. Typical dielectric characterization methods are introduced, and their technical characteristics are analyzed. Furthermore, the performance enhancements of cellulosic triboelectric materials endowed by dielectric modulation, including more efficient energy harvesting, high‐performance wearable electronics, and impedance matching via material strategies, are introduced. Finally, the challenges and future opportunities for cellulose dielectric modulation are summarized.

Abstract: Flexible and stretchable bioelectronics provides a biocompatible interface between electronics and biological systems and has received tremendous attention for in-situ monitoring of various biological systems. Considerable progress in organic electronics has made organic semiconductors, as well as other organic electronic materials, ideal candidates for developing wearable, implantable, and biocompatible electronic circuits due to their potential mechanical compliance and biocompatibility. Organic electrochemical transistors (OECTs), as an emerging member of organic electronic building blocks, exhibit considerable advantages in biological sensing due to the ionic nature at the base of the switch behavior, low driving voltage (<1 V) and high transconductance (in mS range). During the past few years significant progress in constructing flexible/stretchable OECTs (FSOECTs) for both biochemical and bioelectrical sensing has been reported. In this regard, to summarize major research accomplishments in this emerging field, this review first discusses structure and critical features of FSOECTs, including working principle, materials and architectural engineering. Next, a wide spectrum of relevant physiological sensing applications, where FSOECTs are the key components, are summarized. Last, major challenges and opportunities for further advancing FSOECT physiological sensors are discussed. This article is protected by copyright. All rights reserved.