Electroplated Silver-Nickel Core-Shell Nanowire Network Electrodes for Highly Efficient Perovskite Nanoparticle Light-Emitting Diodes

The low sheet resistance and high optical transparency of silver nanowires (AgNWs) make them a promising candidate for use as the flexible transparent electrode of light-emitting diodes (LEDs). In a perovskite LED (PeLED), however, the AgNW electrode can react with the overlying perovskite material by redox reactions, which limit the electroluminescence efficiency of the PeLED by causing the degradation of and generating defect states in the perovskite material. In this study, we prepared Ag-Ni core-shell NW electrodes using the solution-electroplating technique to realize highly efficient PeLEDs based on colloidal formamidinium lead bromide (FAPbBr₃) nanoparticles (NPs). Solvated Ni ions from the NiSO₄ source were deposited onto the surface of AgNW networks in three steps: (i) cathodic cleaning, (ii) adsorption of the Ni-ion complex onto the AgNW surface, and (iii) uniform electrodeposition of Ni. An ultrathin (∼3.5 nm) Ni layer was uniformly deposited onto the AgNW surface, which exhibited a sheet resistance of 16.7 Ω/sq and an optical transmittance of 90.2%. The Ag-Ni core-shell NWs not only increased the work function of the AgNW electrode, which facilitated hole injection into the emitting layer, but also suppressed the redox reaction between Ag and FAPbBr₃ NPs, which prevented the degradation of the emitting layer and the generation of defect states in it. The resulting PeLEDs based on FAPbBr₃ NPs with the Ag-Ni core-shell NWs showed high current efficiency of 44.01 cd/A, power efficiency of 35.45 lm/W, and external quantum efficiency of 9.67%.

Integration of Single-Photon Emitters in 2D Materials with Plasmonic Waveguides at Room Temperature

Efficient integration of a single-photon emitter with an optical waveguide is essential for quantum integrated circuits. In this study, we integrated a single-photon emitter in a hexagonal boron nitride (h-BN) flake with a Ag plasmonic waveguide and measured its optical properties at room temperature. First, we performed numerical simulations to calculate the efficiency of light coupling from the emitter to the Ag plasmonic waveguide, depending on the position and polarization of the emitter. In the experiment, we placed a Ag nanowire, which acted as the plasmonic waveguide, near the defect of the h-BN, which acted as the single-photon emitter. The position and direction of the nanowire were precisely controlled using a stamping method. Our time-resolved photoluminescence measurement showed that the single-photon emission from the h-BN flake was enhanced to almost twice the intensity as a result of the coupling with the Ag nanowire. We expect these results to pave the way for the practical implementation of on-chip nanoscale quantum plasmonic integrated circuits.

Novel Hybrid Conductor of Irregularly Patterned Graphene Mesh and Silver Nanowire Networks

We prepared the hybrid conductor of the Ag nanowire (NW) network and irregularly patterned graphene (GP) mesh with enhanced optical transmittance (~98.5%) and mechano-electric stability (ΔR/R_o: ~42.4% at 200,000 (200k) cycles) under 6.7% strain. Irregularly patterned GP meshes were prepared with a bottom-side etching method using chemical etchant (HNO₃). The GP mesh pattern was judiciously and easily tuned by the regulation of treatment time (0–180 min) and concentration (0–20 M) of chemical etchants. As-formed hybrid conductor of Ag NW and GP mesh exhibit enhanced/controllable electrical-optical properties and mechano-electric stabilities; hybrid conductor exhibits enhanced optical transmittance (TT = 98.5%) and improved conductivity (ΔR_s: 22%) compared with that of a conventional hybrid conductor at similar TT. It is also noteworthy that our hybrid conductor shows far superior mechano-electric stability (ΔR/R_o: ~42.4% at 200k cycles; TT: ~98.5%) to that of controls (Ag NW (ΔR/R_o: ~293% at 200k cycles), Ag NW-pristine GP hybrid (ΔR/R_o: ~121% at 200k cycles)) ascribed to our unique hybrid structure.

Enhancement of Antibacterial Performance of Silver Nanowire Transparent Film by Post-Heat Treatment

Silver nanomaterials (AgNMs) have been applied as antibacterial agents to combat bacterial infections that can cause disease and death. The antibacterial activity of AgNMs can be improved by increasing the specific surface area, so significant efforts have been devoted to developing various bottom-up synthesis methods to control the size and shape of the particles. Herein, we report on a facile heat-treatment method that can improve the antibacterial activity of transparent silver nanowire (AgNW) films in a size-controllable, top-down manner. AgNW films were fabricated via spin-coating and were then heated at different temperatures (230 and 280 °C) for 30 min. The morphology and the degree of oxidation of the as-fabricated AgNW film were remarkably sensitive to the heat-treatment temperature, while the transparency was insensitive. As the heat-treatment temperature increased, the AgNWs spontaneously broke into more discrete wires and droplets, and oxidation proceeded faster. The increase in the heat-treatment temperature further increased the antibacterial activity of the AgNW film, and the heat treatment at 280 °C improved the antibacterial activity from 31.7% to 94.7% for Staphylococcus aureus, and from 57.0% to 98.7% for Escherichia coli. Following commonly accepted antibacterial mechanisms of AgNMs, we present a correlation between the antibacterial activity and surface observations of the AgNW film.

A Highly Sensitive and Broad-Range Pressure Sensor Based on Polyurethane Mesodome Arrays Embedded with Silver Nanowires

The pressure sensor with high sensitivity and a broad pressure sensing range is highly desired for flexible electronics. Here, a high-performance pressure sensor based on a hybrid structure was facilely fabricated using the glass template method, which consists of polyurethane (PU) mesodomes embedded with gradient-distributed silver nanowire (AgNW). Such a novel hybrid architecture enables the as-prepared PU/AgNW pressure sensor to have high sensitivity as well as a wide detection range. Moreover, the obtained PU/AgNW pressure sensors have a fast response time (20 ms), good cycling stability, and excellent flexibility. The pressure sensor, benefiting from its outstanding comprehensive sensing performance, can be used for expression recognition and human activity monitoring, showing tremendous application potential in wearable devices. The proposed architecture and developed methodology in this work is promising for future flexible electronic applications.

Double-Sided Graphene Oxide Encapsulated Silver Nanowire Transparent Electrode with Improved Chemical and Electrical Stability

Owing to their high conductivity, transparency, flexibility, and compatibility with solution processes, silver nanowire (AgNW) networks have been widely explored as a promising alternative to indium tin oxide (ITO). However, their susceptibility to corrosion and thermal instability still remain limiting factors for widespread adoption in a range of devices including solar cells, transparent heaters, and light-emitting diodes. In this study, we report a scalable and economically viable process involving electrophoretic deposition (EPD) to fabricate a highly stable hybrid transparent electrode with a sandwich-like structure, where a AgNW network is covered by graphene oxide (GO) films on both sides. The newly developed all solution process allows the conductive transparent film to be transferred to an arbitrary surface after deposition and demonstrates excellent sheet resistance (15 Ω/sq) and tunable transmittance (70-87% at 550 nm). Unlike bare AgNW networks, the hybrid electrode retains its original conductivity under long-term storage at up to 80% relative humidity. This chemical resilience is explained by the absence of silver corrosion products for the AgNW encapsulated by GO as indicated by X-ray photoelectron spectroscopy. In situ voltage ramping and resistance measurements up to 20 V indicate a novel stabilization mechanism enabled by the presence of GO which delays the failure onset and prevents abrupt divergence of the resistance to the megaohm range experienced by bare AgNW networks. The double-sided nature of the GO coating offers combined stability and performance to the AgNW network, which adds unique versatility of our electrodes to be used toward applications that require a wide range of thermal and chemical stabilities.

Stretchable and High-performance Sensor films Based on Nanocomposite of Polypyrrole/SWCNT/Silver Nanowire

We report the fabrication of stretchable sensor films (SSF) using a composite of functionalized polypyrrole- single-walled carbon nanotube (SWCNT)-silver nanowire hybrid networks embedded into a cross-linked polydimethylsiloxane elastomer. The SSF exhibited low resistivity of 30 Ω/sq and an outstanding mechanical elasticity of up to 25% (no visible change in the sheet resistance after 100 cycle at stretching-release test of 25%). These SSFs were responsive to 1 ppm ammonia gas even at a low temperature of 40 °C with 20% relative humidity and also maintained reproducibility and reversibility when repeatedly exposed to ammonia gas more than 100 times. In addition, it was confirmed that the sensor film was hardly affected even at a relative humidity range of 20% to 80%.

Invisible Silver Nanomesh Skin Electrode via Mechanical Press Welding

Silver nanowire (AgNW) has been studied as an important material for next-generation wearable devices due to its high flexibility, high electrical conductivity and high optical transmittance. However, the inherently high surface roughness of AgNWs and low adhesion to the substrate still need to be resolved for various device applications. In this study, an embedded two-dimensional (2D) Ag nanomesh was fabricated by mechanical press welding of AgNW networks with a three-dimensional (3D) fabric shape into a nanomesh shape, and by embedding the Ag nanomesh in a flexible substrate. The effect of the embedded AgNWs on the physical and electrical properties of a flexible transparent electrode was investigated. By forming embedded nanomesh-type AgNWs from AgNW networks, improvements in physical and electrical properties, such as a 43% decrease in haziness, 63% decrease in sheet resistance, and 26% increase in flexibility, as well as improved adhesion to the substrate and low surface roughness, were observed.

Ultralight, Flexible, and Biomimetic Nanocellulose/Silver Nanowire Aerogels for Electromagnetic Interference Shielding

Ultralight and highly flexible biopolymer aerogels, composed of biomimetic cellular microstructures formed from cellulose nanofibers and silver nanowires, are assembled via a convenient and facile freeze-casting method. The lamellar, honeycomb-like, and random porous scaffolds are successfully achieved by adjusting freezing approaches to modulate the relationships between microstructures and macroscopic mechanical and electromagnetic interference (EMI) shielding performances. Combining the shielding transformation arising from in situ compression and the controlled content of building units, the optimized lamellar porous biopolymer aerogels can show a very high EMI shielding effectiveness (SE), which exceeds 70 or 40 dB in the X-band while the density is merely 6.2 or 1.7 mg/cm³, respectively. The corresponding normalized surface specific SE (defined as the SE divided by the material density and thickness) is up to 178235 dB·cm²/g, far surpassing that of the so-far reported shielding materials. Antibacterial properties and hydrophobicity are also demonstrated extending the versatility and application potential of the biopolymer hybrid aerogels.

Corrosion-Induced Mass Loss Measurement under Strain Conditions through Gr/AgNW-Based, Fe-C Coated LPFG Sensors

In this study, graphene/silver nanowire (Gr/AgNW)-based, Fe-C coated long period fiber gratings (LPFG) sensors were tested up to 72 hours in 3.5 w.t% NaCl solution for corrosion-induced mass loss measurement under four strain levels: 0, 500, 1000 and 1500 µε. The crack and interfacial bonding behaviors of laminate Fe-C and Gr/AgNW layer structures were characterized using Scanning Electron Microscopy (SEM) and electrical resistance measurement. Both optical transmission spectra and electrical impedance spectroscopy (EIS) data were simultaneously measured from each sensor. Under increasing strains, transverse cracks appeared first and were followed by longitudinal cracks on the laminate layer structures. The spacing of transverse cracks and the length of longitudinal cracks were determined by the bond strength at the weak Fe-C and Gr/AgNW interface. During corrosion tests, the shift in resonant wavelength of the Fe-C coated LPFG sensors resulted from the effects of the Fe-C layer thinning and the NaCl solution penetration through cracks on the evanescent field surrounding the LPFG sensors. Compared with the zero-strained sensor, the strain-induced cracks on the laminate layer structures initially increased and then decreased the shift in resonant wavelength in two main stages of the Fe-C corrosion process. In each corrosion stage, the Fe-C mass loss was linearly related to the shift in resonant wavelength under zero strain and with the applied strain taken into account in general cases. The general correlation equation was validated at 700 and 1200 µε to a maximum error of 2.5% in comparison with 46.5% from the zero-strain correlation equation.

Charge Transfer in Nanowire-Embedded PEDOT:PSS and Planar Heterojunction Solar Cells

Hybrid metallic nanowire-embedded, highly conductive poly(3,4-ethylenedioxy thiophene):polystyrenesulfonate (PEDOT:PSS) with synergetic properties is indispensable for enhancing the performances of conductive polymer-based electronic devices. Here, we report embedment of silver nanowires (AgNWs), with diameter ∼100 nm and a high concentration (500 mg/mL) of nanowires dispersed in either ethanol or isopropanol, in PEDOT:PSS and compare the effects of the nanowire-dispersing solvents as well as its thicker diameter and high concentration on the overall properties and particularly its charge transfer characteristics and planar heterojunction solar cell (HSC) properties. Furthermore, electrostatic force microscopy is applied to elucidate the direct charge transfer from AgNWs to the PEDOT:PSS matrix. The AgNW-embedded PEDOT:PSS-based planar HSCs show a very high open-circuit voltage of over 638 mV and a high power conversion efficiency greater than 15.3% and without any significant influence from the AgNW dispersing solvents. While charge transfer in PEDOT:PSS without AgNWs occurs through the conducting PEDOT grains, enhanced charge transfer is realized in AgNW-embedded PEDOT:PSS with charge transport from PEDOT grains to AgNWs and then to PEDOT grains before reaching the top electrode in the HSC. The AgNW-embedded PEDOT:PSS hybrid materials pave a simple way to enhance the charge transfer performance in not only HSCs but also other hybrid or heterojunction electronics.

Silver Nanorings Fabricated by Glycerol-Based Cosolvent Polyol Method

The urgent demand for transparent flexible electrodes applied in wide bandgap devices has promoted the development of new materials. Silver nanoring (AgNR), known as a special structure of silver nanowire (AgNW), exhibits attractive potential in the field of wearable electronics. In this work, an environmentally friendly glycerol-based cosolvent polyol method was investigated. The Taguchi design was utilized to ascertain the factors that affect the yield and ring diameter of AgNRs. Structural characterization showed that AgNR seeds grew at a certain angle during the early nucleation period. The results indicated that the yield and ring diameter of AgNRs were significantly affected by the ratio of cosolvent. Besides, the ring diameter of AgNRs was also tightly related to the concentration of polyvinylpyrrolidone (PVP). The difference of reducibility between glycerol, water, and ethylene glycol leads to the selective growth of (111) plane and is probably the main reason AgNRs are formed. As a result, AgNRs with a ring diameter range from 7.17 to 42.94 μm were synthesized, and the quantity was increased significantly under the optimal level of factors.

Electrodeposited Silver Nanowire Transparent Conducting Electrodes for Thin-Film Solar Cells

Silver nanowire (AgNW) networks have demonstrated high optical and electrical properties, even better than those of indium tin oxide thin films, and are expected to be a next-generation transparent conducting electrode (TCE). Enhanced electrical and optical properties are achieved when the diameter of the AgNWs in the network is fairly small, that is, typically less than 30 nm. However, when AgNWs with such small diameters are used in the network, stability issues arise. One method to resolve the stability issues is to increase the diameter of the AgNWs, but the use of AgNWs with large diameters has the disadvantage of causing a rough surface morphology. In this work, we resolve all of the aforementioned issues with AgNW TCEs by the electrodeposition of Ag onto as-spin-coated thin AgNW TCEs. The electrodeposition of Ag offers many advantages, including the precise adjustment of the AgNW diameter and wire-to-wire welding to improve the junction conductance while minimizing the increase in protrusion height because of the overlap of AgNWs upon increasing the diameter. In addition, Ag electrodeposition on AgNW TCEs can provide higher conductance than that of as-spin-coated AgNW TCEs at the same transparency because of the reduced junction resistance, which generates a superior figure of merit. We applied the electrodeposited (ED) AgNW network to a Cu(In,Ga)Se₂ thin-film solar cell and compared the device performance to a device with a standard sputtered transparent conducting oxide (TCO). The cell fabricated by the electrodeposition method showed nearly equal performance to that of a cell with the sputtered TCO. We expect that ED AgNW networks can be used as high-performance and robust TCEs for various optoelectronic applications.

Fabrication and Performance Evaluation of Highly Sensitive Flexible Strain Sensors with Aligned Silver Nanowires

In this study, we fabricated strain sensors by aligning silver nanowires and transferring them with polydimethylsiloxane (PDMS) and compared the performances of the fabricated strain sensors along the alignment direction. Two types of flexible strain sensors embedded with the aligned silver nanowires were fabricated: one in the longitudinal direction, which is the same as the alignment direction, and the other in the lateral direction, which is perpendicular to the alignment direction. We then evaluated their properties. The proposed longitudinally aligned strain sensor showed the maximum sensitivity (gauge factor (GF) = 89.99) under 25% tensile conditions, which is 7.08 times higher than the sensitivity (GF = 12.71) shown by the laterally aligned strain sensor under 25% tensile conditions. This finding confirmed that the alignment direction of silver nanowires influences the sensitivity of flexible strain sensors. Furthermore, this study demonstrates that the laterally aligned strain sensor (ε > 60%) can be used in wearable devices because it satisfies the required strain range (ε > 50%). Since the strain sensors were fabricated using the temperature-controlled dip coating process, they can be produced at low cost in large quantities, and thus they have advantages for commercialization. These characteristics will be applicable to various flexible devices as well as to flexible strain sensors.

Flexible and Transparent Ferroferric Oxide-Modified Silver Nanowire Film for Efficient Electromagnetic Interference Shielding

Transparent and flexible electromagnetic interference (EMI) shielding film is highly desirable due to the fast-growing flexible electronics. A silver nanowire (Ag NW) film is considered to be an ideal candidate for a transparent and flexible EMI shielding film but suffers low EMI shielding effectiveness (SE) at high transparency and poor bending durability. Herein, we introduce ferroferric oxide (Fe₃O₄) into a Ag NW film and demonstrate a robust EMI shielding film, which exhibits SE of 24.9 dB at 8.2 GHz and optical transparency of 90%. Fe₃O₄ exhibits roles of the improved absorption loss for electromagnetic radiation due to its high permeability, the enhanced reflection loss for electromagnetic radiation by increasing the conductivity of Ag NWs film, and the improved stability for the enhanced adhesion of the Ag NW EMI shielding film. Our work provides a facile method for high-performance transparent EMI shielding film, which exhibits great potential for protection for electronic devices.

Facile Fabrication of Highly Conductive, Ultrasmooth, and Flexible Silver Nanowire Electrode for Organic Optoelectronic Devices

So far, one of the fundamental limitations of silver nanowires (Ag NWs) is the high contact resistance among their junctions. Moreover, a rough surface due to its random arrangement is inevitable to electrical short when the nanowire-based electronics is driving. To improve the contact resistance, we suggest that the particle shape nanocrystals are intentionally reduced at the junctions by a localized joule-heat reduction approach from the silver ions. Via localized reductions, the reduced nanoparticles effectively weld the junction's areas, resulting in a 19% decrease in sheet resistance to 9.9 Ω sq^-1. Besides, the nanowires are embedded into a polyamide film with gentle hot pressing. Consequently, the roughness was considerably dropped so that it was successful to demonstrate organic light-emitting diodes (OLEDs) with nanowires, which was beneficial to be laminated with OLEDs under the low temperature. The experimental results show that the Ag NW-embedded films reach 10.9 Ω sq^-1 of the sheet resistance at 92% transmittance and the roughness was only 1.92 nm.

Stretchable Transparent Wireless Charging Coil Fabricated by Negative Transfer Printing

Wearable electronics, such as smartwatches, VR (virtual reality)/AR (augmented reality) smartglasses, and E-textiles, are an emerging technology platform that is reshaping the way people interact with the surrounding world. However, the power source of these devices can be a critical issue, causing short operational/standby times and frequent charging. Here, a stretchable transparent wireless charging coil fabricated by negative adhesive transfer printing (NATP) is demonstrated. The stretchable transparent conductor is based on the silver nanowire (AgNW)-polyurethane acrylate (PUA) composite with high conductivity and robustness under harsh mechanical treatment. A 10.6 ohm/sq thin film has a transmittance of 84% and is still conductive under a mechanical deformation up to 60% tensile strain. A maximum power of 59 mW (power transfer efficiency ∼24%) is transferred wirelessly. A green-light-emitting diode (LED) was wirelessly powered to illustratively demonstrate the functionality of the system. This work provides an alternative power solution which is compatible with the soft and flexible components of wearable devices.

Flexible and Hierarchical 3D Interconnected Silver Nanowires/Cellulosic Paper-Based Thermoelectric Sheets with Superior Electrical Conductivity and Ultrahigh Thermal Dispersion Capability

To date, various electronic devices have been strategically fabricated, and simultaneous realization of high electrical conductivity, sensing property, and heat-conducting property by a simple, efficient, and accurate approach is significant but still challenging. Here, cellulosic fiber supported 3D interconnected silver nanowire (AgNW) networks with hierarchical structures are rationally designed to achieve excellent electrical conductivity and superior thermal dispersion capability. In particular, thermal annealing at the junctions enables both phonon and electron transfer as well as impedes interfacial slippage. In the current study, the AgNW/cellulosic paper with the low Ag content (1.55 wt %) exhibits a low sheet resistance of 0.51 Ω sq^-1. More importantly, the AgNW/cellulosic paper-based flexible strain sensor has been reasonably developed, which can be applied to monitor various microstructural changes and human motions with high sensitivity and robust stability (fast response/relaxation time of ∼100 ms and high stability >2000 bending-stretching cycles). The AgNW/cellulosic paper-based device also displays efficient thermal dispersion property, which offers exciting opportunities for thermal management application. Furthermore, the obtained hybrid paper exhibits superior heat dispersion capacity for thermal management devices. Overall, uniform dispersion and 3D interconnected junctions of AgNW among the fibers inside the cellulosic papers lead to the combination of high mechanical strength, highly efficient electrical conductivity, and ultrahigh heat dispersion property. The AgNW/cellulosic paper has promising potentials in the flexible and wearable sensing elements, thermal management materials, and artificial intelligence devices.

Enhanced Efficiencies of Perovskite Solar Cells by Incorporating Silver Nanowires into the Hole Transport Layer

In this study, we incorporated silver nanowires (AgNWs) into poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as a hole transport layer (HTL) for inverted perovskite solar cells (PVSCs). The effect of AgNW incorporation on the perovskite crystallization, charge transfer, and power conversion efficiency (PCE) of PVSCs were analyzed and discussed. Compared with neat PEDOT:PSS HTL, incorporation of few AgNWs into PEDOT:PSS can significantly enhance the PCE by 25%. However, the AgNW incorporation may result in performance overestimation due to the lateral charge transfer. The corrosion of AgNWs with a perovskite layer was discussed. Too much AgNW incorporation may lead to defects on the interface between the HTL and the perovskite layer. An extra PEDOT:PSS layer over the pristine PEDOT:PSS-AgNW layer can prevent AgNWs from corrosion by iodide ions.

A Flexible, Robust, and Gel-Free Electroencephalogram Electrode for Noninvasive Brain-Computer Interfaces

Brain-computer interfaces (BCIs) enable direct and near-instant communication between the brain and electronic devices. One of the biggest remaining challenges is to develop an effective noninvasive BCI that allows the recording electrodes to avoid hair on human skin without the inconveniences and complications of using a conductive gel. In this study, we developed a cost-effective, easily manufacturable, flexible, robust, and gel-free silver nanowire/polyvinyl butyral (PVB)/melamine sponge (AgPMS) electroencephalogram (EEG) electrode that circumvents problems with hair. Because of surface metallization by the silver nanowires (AgNWs), the sponge has a high conductivity of 917 S/m while its weight remains the same. The flexible sponge framework and self-locking AgNWs combine to give the new electrode remarkable mechanical stability (the conductivity remains unchanged after 10 000 cycles at 10% compression) and the ability to bypass hair. A BCI application based on steady-state visual evoked potential (SSVEP) measurements on hairless skin shows that the BCI accuracy of the new electrode (86%) is approximately the same as that of conventional electrodes supported by a conductive gel (88%). Most importantly, the performance of the AgPMS on hairy skin is not significantly reduced, which indicates that the new electrode can replace conventional electrodes for both hairless and hairy skin BCIs and other EEG applications.

Constructing a Novel Electroluminescent Device with High-Temperature and High-Humidity Resistance based on a Flexible Transparent Wood Film

Plastic-based electroluminescent devices generally suffer from thermal expansion owing to the high coefficient of thermal expansion (CTE) of the plastic substrate, which reduces the service lifetime of the electroluminescent device. In this study, we employed a delignified veneer synergistically reinforced with epoxy resin as a low-cost substrate for alternating current electroluminescent (ACEL) devices. In brief, the natural interconnected porous structure of wood had a good antideformation capacity to restrict the volume expansion of the epoxy resin under thermal conditions. Furthermore, the impregnation of epoxy resin dramatically improved the optical transmittance of delignified veneer. Considering its low CTE and antideformation capability, the intrinsically high-temperature and high-humidity resistance device based on transparent sliced veneer (TSV) was constructed. Remarkably, the TSV-ACEL device exhibited excellent stability and maintained good luminescence performance even at a high temperature (100 °C, 30 min; as a reference, the poly(ethylene terephthalate)-based ACEL device has stopped operating), completely submerged in water (30 min), or under high-temperature and high-humidity conditions (90 °C, relative humidity: >90%, 30 min). These results pave the way for the realization of flexible and high-temperature resistance ACEL devices.

Highly Bendable and Durable Waterproof Paper for Ultra-High Electromagnetic Interference Shielding

An efficient electromagnetic interference (EMI) shielding paper with excellent water repellency and mechanical flexibility has been developed, by assembling silver nanowires (AgNWs) and hydrophobic inorganic ceramic on the cellulose paper, via a facile dip-coating preparation. Scanning electron microscope (SEM) observations confirmed that AgNWs were interconnected and densely coated on both sides of the cellulose fiber, which endows the as-prepared paper with high conductivity (33.69 S/cm in-plane direction) at a low AgNW area density of 0.13 mg/cm2. Owing to multiple reflections and scattering between the two outer highly conductive surfaces, the obtained composite presented a high EMI shielding effectiveness (EMI SE) of up to 46 dB against the X band, and ultrahigh specific EMI SE of 271.2 dB mm-1. Moreover, the prepared hydrophobic AgNW/cellulose (H-AgNW/cellulose) composite paper could also maintain high EMI SE and extraordinary waterproofness (water contact angle > 140°) by suffering dozens of bending tests or one thousand peeling tests. Overall, such a multifunctional paper might have practical applications in packaging conductive components and can be used as EMI shielding elements in advanced application areas, even under harsh conditions.

Facile Preparation of Hybrid Structure Based on Mesodome and Micropillar Arrays as Flexible Electronic Skin with Tunable Sensitivity and Detection Range

The development of flexible pressure sensors has attracted increasing research interest for potential applications such as wearable electronic skins and human healthcare monitoring. Herein, we demonstrated a piezoresistive pressure sensor based on AgNWs-coated hybrid architecture consisting of mesoscaled dome and microscaled pillar arrays. We experimentally showed that the key three-dimensional component for a pressure sensor can be conveniently acquired using a vacuum application during the spin-coating process instead of a sophisticated and expensive approach. The demonstrated hybrid structure exhibits dramatically improved sensing capability when compared with the conventional one-fold dome-based counterpart in terms of the sensitivity and detectable pressure range. The optimized sensing performance, by integrating D1000 dome and D50P100 MPA, reaches a superior sensitivity of 128.29 kPa^-1 (0-200 Pa), 1.28 kPa^-1 (0.2-10 kPa), and 0.26 kPa^-1 (10-80 kPa) and a detection limit of 2.5 Pa with excellent durability. As a proof-of-concept, the pressure sensor based on the hybrid configuration was demonstrated as a versatile platform to accurately monitor different kinds of physical signals or pressure sources, e.g., wrist pulse, voice vibration, finger bending/touching, gas flow, as well as address spatial loading. We believe that the proposed architecture and developed methodology can be promising for future applications including flexible electronic devices, artificial skins, and interactive robotics.

High Brightness Organic Light-Emitting Diodes with Capillary-Welded Hybrid Diameter Silver Nanowire/Graphene Layers as Electrodes

The development of silver nanowire electrodes is always limited due to some disadvantages, such as roughness, oxidative properties, and other disadvantages. In this research, a capillary-welded silver nanowire/graphene composite film was used as an electrode for organic light-emitting diode (OLED) devices. As an encapsulation layer, graphene reduced the surface roughness and the oxidation probability of silver nanowires. The composite electrode showed an excellent transmittance of 91.5% with low sheet resistant of 26.4 ohm/sq. The devices with the silver nanowire/graphene composite electrode emitted green electroluminescence at 516 nm, and the turn-on voltage was about 3.8 V. The maximum brightness was 50810 cd/cm², which is higher than the indium tin oxide-based (ITO-based) devices with the same configuration. Finally, it was proved that the silver nanowire/graphene composite electrodes possessed better heat dissipation than the ITO-based ones under energization. In summary, it means that this novel silver nanowires/graphene electrode has great potential in OLED device applications.

High-Performance Transparent Quantum Dot Light-Emitting Diode with Patchable Transparent Electrodes

Patchable electrodes are attractive for applications in optoelectronic devices because of their easy and reliable processability. However, development of reliable patchable transparent electrodes (TEs) with high optoelectronic performance is challenging; till now, optoelectronic devices fabricated with patchable TEs have been exhibiting limited performance. In this study, Ag nanowire (AgNW)/poly(methyl methacrylate) (PMMA) patchable TEs are developed and the highly efficient transparent quantum dot light-emitting diodes (QLEDs) using the patchable TEs are fabricated. AgNWs with optimized optoelectronic properties (figure of merit ≈ 3.3 × 10^-2) are coated by an ultrathin PMMA nanolayer and transferred to thermal release tapes that enable physical attachment of TEs on the QLEDs without a significant damage to the adjacent active layer. The transparent QLEDs using patchable transparent top electrodes display excellent performance, with the maximum total luminance and current efficiency of 27 310 cd·m^-2 and 45.99 cd·A^-1, respectively. Fabricated by all-solution-based processes, these QLEDs exhibit the best performance to date among devices adopting patchable top electrodes.