Showing papers on "Flexible electronics published in 2014"
TL;DR: A review of electronic devices based on two-dimensional materials, outlining their potential as a technological option beyond scaled complementary metal-oxide-semiconductor switches and the performance limits and advantages, when exploited for both digital and analog applications.
Abstract: The compelling demand for higher performance and lower power consumption in electronic systems is the main driving force of the electronics industry's quest for devices and/or architectures based on new materials. Here, we provide a review of electronic devices based on two-dimensional materials, outlining their potential as a technological option beyond scaled complementary metal-oxide-semiconductor switches. We focus on the performance limits and advantages of these materials and associated technologies, when exploited for both digital and analog applications, focusing on the main figures of merit needed to meet industry requirements. We also discuss the use of two-dimensional materials as an enabling factor for flexible electronics and provide our perspectives on future developments.
2,531 citations
TL;DR: An efficient, low-cost fabrication strategy to construct a highly sensitive, flexible pressure sensor by sandwiching ultrathin gold nanowire-impregnated tissue paper between two thin polydimethylsiloxane sheets is reported, enabling facile large-area integration and patterning for mapping spatial pressure distribution.
Abstract: Flexible electronics hold great promise for wearable biomedical sensors. Here, the authors report a pressure sensor composed of gold nanowire-impregnated tissue paper, sandwiched between polydimethylsiloxane sheets, and demonstrate that the design is appropriate for large-area flexible electronics.
1,678 citations
TL;DR: In this paper, the authors summarized the recent research progress of flexible lithium-ion batteries, with special emphasis on electrode material selectivity and battery structural design, and discussed the prospects and challenges toward the practical uses of flexible batteries in electronic devices.
Abstract: With the advent of flexible electronics, flexible lithium-ion batteries have attracted great attention as a promising power source in the emerging field of flexible and wearable electronic devices such as roll-up displays, touch screens, conformable active radio-frequency identification tags, wearable sensors and implantable medical devices. In this review, we summarize the recent research progress of flexible lithium-ion batteries, with special emphasis on electrode material selectivity and battery structural design. We begin with a brief introduction of flexible lithium-ion batteries and the current development of flexible solid-state electrolytes for applications in this field. This is followed by a detailed overview of the recent progress on flexible electrode materials based on carbon nanotubes, graphene, carbon cloth, conductive paper (cellulose), textiles and some other low-dimensional nanostructured materials. Then recently proposed prototypes of flexible cable/wire type, transparent and stretchable lithium-ion batteries are highlighted. The latest advances in the exploration of other flexible battery systems such as lithium–sulfur, Zn–C (MnO2) and sodium-ion batteries, as well as related electrode materials are included. Finally, the prospects and challenges toward the practical uses of flexible lithium-ion batteries in electronic devices are discussed.
1,271 citations
TL;DR: In this paper, a number of cubic crystals, two-dimensional layered materials, nanostructure networks and composites, molecular layers and surface functionalization, and aligned polymer structures are examined for potential applications as heat spreading layers and substrates, thermal interface materials, and underfill materials in future-generation electronics.
1,269 citations
TL;DR: Flexible solid-state supercapacitors (SCs) have attracted increasing interest because they can provide substantially higher specific/volumetric energy density compared to conventional capacitors.
Abstract: Increasing power and energy demands for next-generation portable and flexible electronics such as roll-up displays, photovoltaic cells, and wearable devices have stimulated intensive efforts to explore flexible, lightweight and environmentally friendly energy storage devices. Flexible solid-state supercapacitors (SCs) have attracted increasing interest because they can provide substantially higher specific/volumetric energy density compared to conventional capacitors. Additionally, flexible solid-state SCs are typically small in size, highly reliable, light-weight, easy to handle, and have a wide range of operation temperatures. In this regard, solid-state SCs hold great promise as new energy storage devices for flexible and wearable electronics. In this article, we review recent achievements in the design, fabrication and characterization of flexible solid-state SCs. Moreover, we also discuss the current challenges and future opportunities for the development of high-performance flexible solid-state SCs.
1,105 citations
TL;DR: In this article, an overview of the remarkable contributions made by the leading scientists in this important and promising research area is given, and some perspectives for the future and impacts of flexible energy storage and conversion systems are also proposed.
Abstract: To meet the rapid development of flexible, portable, and wearable electronic devices, extensive efforts have been devoted to develop matchable energy storage and conversion systems as power sources, such as flexible lithium-ion batteries (LIBs), supercapacitors (SCs), solar cells, fuel cells, etc. Particularly, during recent years, exciting works have been done to explore more suitable and effective electrode/electrolyte materials as well as more preferable cell configuration and structural designs to develop flexible power sources with better electrochemical performance for integration into flexible electronics. An overview is given for these remarkable contributions made by the leading scientists in this important and promising research area. Some perspectives for the future and impacts of flexible energy storage and conversion systems are also proposed.
736 citations
TL;DR: This study demonstrates the potential of two-dimensional layered semiconductors for high-speed flexible electronics by showing that logic inverters or radio frequency amplifiers can be formed by integrating multiple MoS2 transistors on quartz or flexible substrates with voltage gain in the gigahertz regime.
Abstract: Molybdenum disulfide holds great potential for advanced flexible electronic devices. Here, using a transferred gate technique, the authors fabricate molybdenum disulfide-based transistors with optimized device geometry and contact, improving device speed and demonstrating gigahertz circuits with voltage gain.
411 citations
TL;DR: A facile fast laser nanoscale welding process uses the plasmonic effect at a nanowire (NW) junction to suppress oxidation and successfully fabricate a Cu-NW-based percolation-network conductor.
Abstract: A facile fast laser nanoscale welding process uses the plasmonic effect at a nanowire (NW) junction to suppress oxidation and successfully fabricate a Cu-NW-based percolation-network conductor. The "nanowelding" process does not require an inert or vacuum environment. Due to the low-temperature and fast-process nature, plasmonic laser nanowelding may form Cu-nanowire networks on heat-sensitive, flexible or even stretchable substrates.
399 citations
TL;DR: This work aims to demonstrate the efforts towards in-situ applicability of EMMARM, which aims to provide real-time information about the physical properties of EMTs and their applications in a number of industrial settings.
Abstract: Dr. S.-W. Hwang, J.-K. Song, Dr. X. Huang, Dr. S.-K. Kang, Dr. B. H. Kim, J.-H. Kim Department of Materials Science and Engineering and Frederick Seitz Materials Research Laboratory University of Illinois at Urbana-Champaign, Urbana IL 61801 , USA H. Cheng, Prof. Y. Huang Department of Mechanical Engineering Civil and Environmental Engineering Center for Engineering and Health and Skin Disease Research Center Northwestern University, Evanston IL 60208 , USA S. Yu Department of Chemical and Biomolecular Engineering University of Illinois at Urbana-Champaign, Urbana IL 61801 , USA Prof. J. A. Rogers Department of Materials Sicience and Engineering Chemistry, Mechanical Science and Engineering Electrical and Computer Engineering Beckman Institute for Advanced Science and Technology and Frederick Seitz Materials research Laboratory University of Illinois at Urbana-Champaign, Urbana IL 61801 , USA E-mail: jrogers@illinois.edu
340 citations
TL;DR: The hybrid yarn's blended structure, resulting from trapping of MnO2 in its internal pores, effectively enlarges electrochemical area and reduces charge diffusion length, and the yarn supercapacitor exhibits high values of capacitance, energy density, and average power density.
Abstract: Electrochemical deposition of MnO2 onto carbon nanotube (CNT) yarn gives a high-performance, flexible yarn supercapacitor. The hybrid yarn's blended structure, resulting from trapping of MnO2 in its internal pores, effectively enlarges electrochemical area and reduces charge diffusion length. Accordingly, the yarn supercapacitor exhibits high values of capacitance, energy density, and average power density. Applications in wearable electronics can be envisaged.
331 citations
TL;DR: To the best of the knowledge, this is the first report of all 2D transparent TFT fabricated on flexible substrate along with the highest mobility and current ON-OFF ratio.
Abstract: In this article, we report only 10 atomic layer thick, high mobility, transparent thin film transistors (TFTs) with ambipolar device characteristics fabricated on both a conventional silicon platform as well as on a flexible substrate. Monolayer graphene was used as metal electrodes, 3–4 atomic layers of h-BN were used as the gate dielectric, and finally bilayers of WSe2 were used as the semiconducting channel material for the TFTs. The field effect carrier mobility was extracted to be 45 cm2/(V s), which exceeds the mobility values of state of the art amorphous silicon based TFTs by ∼100 times. The active device stack of WSe2–hBN–graphene was found to be more than 88% transparent over the entire visible spectrum and the device characteristics were unaltered for in-plane mechanical strain of up to 2%. The device demonstrated remarkable temperature stability over 77–400 K. Low contact resistance value of 1.4 kΩ-μm, subthreshold slope of 90 mv/decade, current ON–OFF ratio of 107, and presence of both electr...
TL;DR: Gravure printing of graphene is demonstrated for the rapid production of conductive patterns on flexible substrates, providing an efficient method for the integration of graphene into large-area printed and flexible electronics.
Abstract: Gravure printing of graphene is demonstrated for the rapid production of conductive patterns on flexible substrates. Development of suitable inks and printing parameters enables the fabrication of patterns with a resolution down to 30 μm. A mild annealing step yields conductive lines with high reliability and uniformity, providing an efficient method for the integration of graphene into large-area printed and flexible electronics.
TL;DR: A fully printed fingerprint-like three-axis tactile force and temperature sensor for artificial skin applications and strain engineering enables the strain distribution to be detected upon applying a slip/friction force is demonstrated.
Abstract: A three-axis tactile force sensor that determines the touch and slip/friction force may advance artificial skin and robotic applications by fully imitating human skin. The ability to detect slip/friction and tactile forces simultaneously allows unknown objects to be held in robotic applications. However, the functionalities of flexible devices have been limited to a tactile force in one direction due to difficulties fabricating devices on flexible substrates. Here we demonstrate a fully printed fingerprint-like three-axis tactile force and temperature sensor for artificial skin applications. To achieve economic macroscale devices, these sensors are fabricated and integrated using only printing methods. Strain engineering enables the strain distribution to be detected upon applying a slip/friction force. By reading the strain difference at four integrated force sensors for a pixel, both the tactile and slip/friction forces can be analyzed simultaneously. As a proof of concept, the high sensitivity and selectivity for both force and temperature are demonstrated using a 3×3 array artificial skin that senses tactile, slip/friction, and temperature. Multifunctional sensing components for a flexible device are important advances for both practical applications and basic research in flexible electronics.
TL;DR: The approach introduced here is simple, cost-effective, and well-suited for large-scale high-performance flexible NG fabrication and demonstrates the important role of hemispherical BTO clusters.
Abstract: We report high-performance flexible nanogenerators (NGs) based on a composite thin film, composed of hemispherically aggregated BaTiO3 nanoparticles (NPs) and poly(vinylidene fluoride-co-hexafluoropropene) P(VDF-HFP). The hemispherical BTO–P(VDF-HFP) clusters were realized by a solvent evaporation method, which greatly enhanced piezoelectric power generation. The flexible NGs exhibit high electrical output up to ∼75 V and ∼15 μA at the applied force normal to the surface, indicating the important role of hemispherical BTO clusters. Besides, the durability and reproducibility of the NGs were tested by cyclic measurement under bending stage, generating the output of ∼5 V and ∼750 nA. The approach we introduce here is simple, cost-effective, and well-suited for large-scale high-performance flexible NG fabrication.
TL;DR: In this paper, a thin transparent nanopaper-based high-mobility organic thin-film transistor (OTFT) array is demonstrated for the first time on cellulose nanofiber paper.
Abstract: Eco-friendly and low-cost cellulose nanofiber paper (nanopaper) is a promising candidate as a novel substrate for flexible electron device applications. Here, a thin transparent nanopaper-based high-mobility organic thin-film transistor (OTFT) array is demonstrated for the first time. Nanopaper made from only native wood cellulose nanofibers has excellent thermal stability (>180 °C) and chemical durability, and a low coefficient of thermal expansion (CTE: 5–10 ppm K-1). These features make it possible to build an OTFT array on nanopaper using a similar process to that for an array on conventional glass. A short-channel bottom-contact OTFT is successfully fabricated on the nanopaper by a lithographic and solution-based process. Owing to the smoothness of the cast-coated nanopaper surface, a solution processed organic semiconductor film on the nanopaper comprises large crystalline domains with a size of approximately 50–100 μm, and the corresponding TFT exhibits a high hole mobility of up to 1 cm2V-1 s-1 and a small hysteresis of below 0.1 V under ambient conditions. The nanopaper-based OTFT also had excellent flexibility and can be formed into an arbitrary shape. These combined technologies of low-cost and eco-friendly paper substrates and solution-based organic TFTs are promising for use in future flexible electronics application such as flexible displays and sensors.
TL;DR: In this paper, the advances in alternative sintering approaches for conductive, metal containing inks, which can be processed by inkjet-printing processes are examined regarding their mechanism, their compatibility with commonly used materials in the field of flexible electronics, its compatibility with high-throughput manufacturing processes and its applicability to the production of flexible electronic devices.
Abstract: Well-defined high resolution structures with excellent electrical conductivities are key components of almost every electronic device. Producing these by printing metal based conductive inks on polymer foils represents an important step forward towards the manufacturing of plastic electronic products on an industrial scale. The development of fast, efficient and inexpensive post-deposition sintering technologies for these materials is an important processing step to make this approach commercially viable. This review discusses the advances in alternative sintering approaches for conductive, metal containing inks, which can be processed by inkjet-printing processes. Each sintering approach is examined regarding its mechanism, its compatibility with commonly used materials in the field of flexible electronics, its compatibility with high-throughput manufacturing processes and its applicability to the production of flexible electronic devices.
TL;DR: The resulting high conductivity of the printed silver patterns reached over 20% of the bulk silver value under ambient conditions, which enabled the fabrication of flexible electronic devices, as demonstrated by the inkjet printing of conductive circuits of LED devices.
Abstract: Silver nanoparticles (NPs) which could be kept in solid form and were easily stored without degeneration or oxidation at room temperature for a long period of time were synthesized by a simple and environmentally friendly wet chemistry method in an aqueous phase. Highly stable dispersions of aqueous silver NP inks, sintered at room temperature, for printing highly conductive tracks (∼8.0 μΩ cm) were prepared simply by dispersing the synthesized silver NP powder in water. These inks are stable, fairly homogeneous and suitable for a wide range of patterning techniques. The inks were successfully printed on paper and polyethylene terephthalate (PET) substrates using a common color printer. Upon annealing at 180 °C, the resistivity of the printed silver patterns decreased to 3.7 μΩ cm, which is close to twice that of bulk silver. Various factors affecting the resistivity of the printed silver patterns, such as annealing temperature and the number of printing cycles, were investigated. The resulting high conductivity of the printed silver patterns reached over 20% of the bulk silver value under ambient conditions, which enabled the fabrication of flexible electronic devices, as demonstrated by the inkjet printing of conductive circuits of LED devices.
TL;DR: In this paper, a focused electron beam was used to fabricate one-dimensional conducting nanowires from transition-metal dichalcogenide monolayers, which can be used as interconnects in future flexible nanocircuits.
Abstract: In the pursuit of ultrasmall electronic components, monolayer electronic devices have recently been fabricated using transition-metal dichalcogenides. Monolayers of these materials are semiconducting, but nanowires with stoichiometry MX (M = Mo or W, X = S or Se) have been predicted to be metallic. Such nanowires have been chemically synthesized. However, the controlled connection of individual nanowires to monolayers, an important step in creating a two-dimensional integrated circuit, has so far remained elusive. In this work, by steering a focused electron beam, we directly fabricate MX nanowires that are less than a nanometre in width and Y junctions that connect designated points within a transition-metal dichalcogenide monolayer. In situ electrical measurements demonstrate that these nanowires are metallic, so they may serve as interconnects in future flexible nanocircuits fabricated entirely from the same monolayer. Sequential atom-resolved Z-contrast images reveal that the nanowires rotate and flex continuously under momentum transfer from the electron beam, while maintaining their structural integrity. They therefore exhibit self-adaptive connections to the monolayer from which they are sculpted. We find that the nanowires remain conductive while undergoing severe mechanical deformations, thus showing promise for mechanically robust flexible electronics. Density functional theory calculations further confirm the metallicity of the nanowires and account for their beam-induced mechanical behaviour. These results show that direct patterning of one-dimensional conducting nanowires in two-dimensional semiconducting materials with nanometre precision is possible using electron-beam-based techniques.
TL;DR: This work investigated the effect of capillary number, semiconductor ink composition (small molecule-polymer ratio), and additive high boiling point solvent concentrations on film fidelity, pattern design, device performance and yields.
Abstract: A combination of surface energy-guided blade coating and inkjet printing is used to fabricate an all-printed high performance, high yield, and low variability organic thin film transistor (OTFT) array on a plastic substrate. Functional inks and printing processes were optimized to yield self-assembled homogenous thin films in every layer of the OTFT stack. Specifically, we investigated the effect of capillary number, semiconductor ink composition (small molecule-polymer ratio), and additive high boiling point solvent concentrations on film fidelity, pattern design, device performance and yields.
TL;DR: Koga et al. as mentioned in this paper used silver nanowires or carbon nanotubes as conductive material to obtain uniform networks, thus avoiding the uneven distribution that typically occurs with plastic-based substrates.
Abstract: Paper has been used throughout history for numerous purposes and continues to be extremely useful. The cellulose-based material has even been investigated as a support for flexible electronics. Traditional paper, however, does not provide the transparency that is increasingly sought after in this field. Now, Hirotaka Koga, Masaya Nogi and co-workers from Osaka University, Japan, have coated a type of transparent paper that they previously developed with conductive materials. Their paper is based on cellulose nanofibers rather than the microfibers from which traditional paper is composed. The team used silver nanowires or carbon nanotubes as the conductive material—both show promise in transparent flexible electronics that employ plastic substrates. By depositing the silver or carbon on the ‘cellulose nanopaper’ through a simple filtration process, the researchers obtained uniform networks, thus avoiding the uneven distribution that typically occurs with plastic-based substrates. The resulting flexible materials showed good conductivity and optical transparency.
TL;DR: The lead-free flexible nanocomposite generator (NCG) made by a simple spin-casting method successfully converted mechanical energy to electricity up to 12 V and 1.2 μA as discussed by the authors.
Abstract: The lead-free nanocomposite generator device for high-output energy harvesting using piezoelectric alkaline niobate-based particles (KNLN) and copper (Cu) nanorods filler is reported. To produce the piezoelectric nanocomposite (p-NC), lead-free KNLN particles synthesized using a solid-state method and the Cu nanorods are distributed in a polydimethylsiloxane (PDMS) matrix. The lead-free flexible nanocomposite generator (NCG) made by a simple spin-casting method successfully converts mechanical energy to electricity up to 12 V and 1.2 μA. These are higher than previously reported outputs from other lead-free and composite-based nanogenerators. The harvested energy is utilized to directly turn on white light emitting diodes (LEDs) without external circuits and to operate a complex circuital liquid crystal display (LCD). A large-area NCG device (30 cm × 30 cm) is also fabricated using the bar-coating method to obtain maximum output up to 140 V and 8 μA (≈0.5 mW). This NCG technology has substantial advantages as a simple, cost-effective, scalable, and high-throughput approach for practical flexible electronics, bio-eco-compatible self-powered systems, and body sensor networks (BSN).
TL;DR: Electrospinning and electroless deposition is combined to synthesize interconnected, ultralong MNW networks, which opens new opportunities for flexible electronics and roll-to-roll large-scale manufacturing.
Abstract: Metal nanowire (MNW) transparent electrodes have been widely developed for their promising sheet resistance (Rs)–transmittance (T) performance, excellent mechanical flexibility, and facile synthesis. How to lower the junction resistance without compromising optical transmittance has become the key issue in enhancing their performance. Here we combine electrospinning and electroless deposition to synthesize interconnected, ultralong MNW networks. For both silver and copper nanowire networks, the Rs and T values reach around 10 Ω/sq and 90%, respectively. This process is scalable and takes place at ambient temperature and pressure, which opens new opportunities for flexible electronics and roll-to-roll large-scale manufacturing.
TL;DR: It is reported that screen printing, which is a simple, scalable, and cost-effective technique, can be used to produce both rigid and flexible thin-film transistors using separated single-wall carbon nanotubes.
Abstract: Semiconducting single-wall carbon nanotubes are very promising materials in printed electronics due to their excellent mechanical and electrical property, outstanding printability, and great potential for flexible electronics. Nonetheless, developing scalable and low-cost approaches for manufacturing fully printed high-performance single-wall carbon nanotube thin-film transistors remains a major challenge. Here we report that screen printing, which is a simple, scalable, and cost-effective technique, can be used to produce both rigid and flexible thin-film transistors using separated single-wall carbon nanotubes. Our fully printed top-gated nanotube thin-film transistors on rigid and flexible substrates exhibit decent performance, with mobility up to 7.67 cm2 V–1 s–1, on/off ratio of 104 ∼ 105, minimal hysteresis, and low operation voltage (<10 V). In addition, outstanding mechanical flexibility of printed nanotube thin-film transistors (bent with radius of curvature down to 3 mm) and driving capability f...
TL;DR: The production of transparent conductive patterns, and arrays composed of connected CNT "coffee rings" on a flexible substrate poly(ethylene terephthalate), has been reported, which makes such films very promising as transparent conductors for various electronic devices, as demonstrated by using an electroluminescent device.
Abstract: Transparent and flexible conductors are a major component in many modern optoelectronic devices, such as touch screens for smart phones, displays, and solar cells. Carbon nanotubes (CNTs) offer a good alternative to commonly used conductive materials, such as metal oxides (e.g. ITO) for flexible electronics. The production of transparent conductive patterns, and arrays composed of connected CNT “coffee rings” on a flexible substrate poly(ethylene terephthalate), has been reported. Direct patterning is achieved by inkjet printing of an aqueous dispersion of CNTs, which self-assemble at the rim of evaporating droplets. After post-printing treatment with hot nitric acid, the obtained TCFs are characterized by a sheet resistance of 156 Ω sq−1 and transparency of 81% (at 600 nm), which are the best reported values obtained by inkjet printing of conductive CNTs. This makes such films very promising as transparent conductors for various electronic devices, as demonstrated by using an electroluminescent device.
TL;DR: In this paper, a self-powered all-flexible electronic system with light emittance can be spontaneously achieved by the electricity produced from flexible thin-film generator by applying slight biomechanical energy without any externally applied energy storage.
Abstract: Energy-harvesting technology utilising mechanical energy sources is a promising approach for the sustainable, independent, and permanent operation of a variety of flexible electronics. A new concept of a fully-flexible light-emitting system, self-powered by a high-performance piezoelectric thin-film energy harvester has been first established by manipulating highly-robust, flexible, vertically structured light emitting diodes (f-VLEDs). The f-VLEDs fabricated by anisotropic conductive film bonding and entire wafer etching show stable and durable performances during periodic mechanical deformations. A high-output energy harvester capable of generating up to 140 V and 10 μA can be fabricated via laser lift-off (LLO) process widely used in industries, in a safe and robust manner. In particular, this LLO process is of great benefit for the fabrication of mechanically stable, flexible piezoelectric devices, without causing any degradation of piezoelectric properties. In this process, self-powered all-flexible electronic system with light emittance can be spontaneously achieved by the electricity produced from flexible thin-film generator by applying slight biomechanical energy without any externally applied energy storage. This conceptual technology of self-powering based on the conversion of mechanical energy to electrical energy can open a facile and robust avenue for diverse, self-powered, bio-implantable applications, as well as commercial display applications.
TL;DR: In this article, a 3D hierarchical MoS2 nanoflake array/carbon cloth has been synthesized for improving the performance of flexible LiCoO2 battery anodes, which has a high reversible capacity of 3.0-3.5 mA h cm−2 at a current density of 0.15 mA cm −2 and outstanding discharging/charging rate stability.
Abstract: Flexible lithium-ion batteries are the key to powering a new generation of flexible electronics such as roll-up displays, smart electronics, and wearable devices. Here we report, for the first time, one-step hydrothermal synthesis of a three-dimensional (3D) hierarchical MoS2 nanoflake array/carbon cloth which shows potential for improving the performance of flexible lithium-ion batteries. Structural characterizations show that the 3D hierarchical MoS2 nanoflake array/carbon cloth has a similar ordered woven structure to the bare carbon cloth. Each carbon microfiber is covered with many highly ordered 3D MoS2 nanoflake arrays, and a typical MoS2 nanoflake, with expanded spacing of the (002) crystal plane, has a uniform width of about 400 nm and a thickness of less than 15 nm. The flexible 3D MoS2 nanoflake array/carbon cloth as a flexible lithium-ion battery anode has a high reversible capacity of 3.0–3.5 mA h cm−2 at a current density of 0.15 mA cm−2 and outstanding discharging/charging rate stability. Moreover, a fabricated full battery, with commercial LiCoO2 powder and the hierarchical architectures as electrodes, exhibits high flexibility and good electrochemical performance, and can light a commercial red LED even after 50 cycles of bending the full battery.
TL;DR: A review of the structure, properties, and emerging device applications of these materials is presented in this paper, where an overview of the synthesis routes that can potentially enable scalable avenues for forming these 2D atomic crystals is also discussed.
Abstract: Graphene’s layered structure has opened new prospects for the exploration of properties of other monolayer-thick two-dimensional (2D) layered crystals. The emergence of these inorganic 2D atomic crystals beyond graphene promises a diverse spectrum of properties. For example, hexagonal-boron nitride (h-BN), a layered material closest in structure to graphene is an insulator, while niobium selenide (NbSe2), a transition metal dichalcogenide, is metallic, and monolayers of other transition metal dichalcogenides such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2) are direct band gap semiconductors. The rich spectrum of properties exhibited by these 2D layered material systems can potentially be engineered on-demand and creates exciting prospects for using such systems in device applications ranging from electronics, photonics, energy harvesting, flexible electronics, transparent electrodes, and sensing. A review of the structure, properties, and the emerging device applications of these materials is presented in this paper. While the layered structure of these materials makes them amenable to mechanical exfoliation for quickly unveiling their novel properties and for fabricating proof-of-concept devices, an overview of the synthesis routes that can potentially enable scalable avenues for forming these 2D atomic crystals is also discussed.
TL;DR: A recently developed full-solution processing strategy, polymer-assisted metal deposition (PAMD), which is particularly suitable for the roll-to-roll, low-cost fabrication of high-performance compliant metal conductors on a wide variety of organic substrates including plastics, elastomers, papers, and textiles is highlighted.
Abstract: Metal interconnects, contacts, and electrodes are indispensable elements for most applications of flexible, stretchable, and wearable electronics. Current fabrication methods for these metal conductors are mainly based on conventional microfabrication procedures that have been migrated from Si semiconductor industries, which face significant challenges for organic-based compliant substrates. This Research News highlights a recently developed full-solution processing strategy, polymer-assisted metal deposition (PAMD), which is particularly suitable for the roll-to-roll, low-cost fabrication of high-performance compliant metal conductors (Cu, Ni, Ag, and Au) on a wide variety of organic substrates including plastics, elastomers, papers, and textiles. This paper presents i) the principles of PAMD, and how to use it for making ii) flexible, stretchable, and wearable conductive metal electrodes, iii) patterned metal interconnects, and d) 3D stretchable and compressible metal sponges. A critical perspective on this emerging strategy is also provided.
TL;DR: In this article, a new class of biofriendly ionogels produced by gelation of microcellulose thin films with tailored 1-ethyl-3-methylimidazolium methylphosphonate ionic liquids are demonstrated.
Abstract: A new class of biofriendly ionogels produced by gelation of microcellulose thin films with tailored 1-ethyl-3-methylimidazolium methylphosphonate ionic liquids are demonstrated. The cellulose ionogels show promising properties for application in flexible electronics, such as transparency, flexibility, transferability, and high specific capacitances of 5 to 15 μF cm−2. They can be laminated onto any substrate such as multilayer-coated paper and act as high capacitance dielectrics for inorganic (spray-coated ZnO and colloidal ZnO nanorods) and organic (poly[3-hexylthiophene], P3HT) electrolyte-gated field-effect transistors (FETs), that operate at very low voltages (<2 V). Field-effect mobilities in ionogel-gated spray-coated ZnO FETs reach 75 cm2 V−1 s−1 and a typical increase of mobility with decreasing specific capacitance of the ionogel is observed. Solution-processed, colloidal ZnO nanorods and laminated cellulose ionogels enable the fabrication of the first electrolyte-gated, flexible circuits on paper, which operate at bending radii down to 1.1 mm.
TL;DR: A unique form of adaptive electronics is demonstrated, which change their mechanical properties from rigid and planar to soft and compliant, in order to enable soft and conformal wrapping around 3D objects, including biological tissue.
Abstract: A unique form of adaptive electronics is demonstrated, which change their mechanical properties from rigid and planar to soft and compliant, in order to enable soft and conformal wrapping around 3D objects, including biological tissue. These devices feature excellent mechanical robustness and maintain initial electrical properties even after changing shape and stiffness.