Highly Conducting MXene-Silver Nanowire Transparent Electrodes for Flexible Organic Solar Cells

MXene, a new class of two-dimensional materials, offers a unique combination of metallic conductivity and hydrophilicity. This material has shown great promise in numerous applications including electromagnetic interference shielding, sensing, energy storage, and catalysis. In this paper, we report on the fabrication of transparent, conductive, and flexible MXene/silver nanowire (AgNW) hybrid films, resulting in the highest figure of merit (162.49) in the reported literature to date regarding an MXene-based transparent electrode. The hybrid films, prepared via a simple and scalable solution-processed method, exhibit good electrical conductivity, high transmittance, low roughness, work function matching, and robust mechanical performance. Following film fabrication, the hybrid electrodes were demonstrated to function as transparent electrodes in fullerene molecule PTB7-Th:PC71BM and nonfullerene molecule PBDB-T:ITIC organic photovoltaics (OPVs). In an effort to further improve the performance of flexible OPVs, a ternary structure of PBDB-T:ITIC:PC71BM was demonstrated, resulting in a power conversion efficiency (PCE) of 8.30%. Mechanical properties were also quantified, with the flexible ternary organic solar cells capable of retaining 84.6% of the original PCE after 1000 bending and unbending cycles to a 5 mm bending radius. These optoelectronic and mechanical performance metrics represent a breakthrough in the field of flexible optoelectronics.

Optoelectronic and Electrothermal Properties of Transparent Conductive Silver Nanowires Films

Silver nanowires (AgNWs) show promise for fabricating flexible transparent conductors owing to their excellent conductivity, high transparency, and good mechanical properties. Here, we present the fabrication of transparent films composed of AgNWs with diameters of 20-30 nm and lengths of 25-30 μm on polyethylene terephthalate substrates and glass slides substrates using the Meyer rod method. We systematically investigated the films' optoelectronic and electrothermal properties. The morphology remained intact when heated at 25-150 °C and the AgNWs film showed high conductivity (17.6-14.3 Ω∙sq-1), excellent transmittance (93.9-91.8%) and low surface roughness values (11.2-14.7 nm). When used as a heater, the transparent AgNW conductive film showed rapid heating at low input voltages owing to a uniform heat distribution across the whole substrate surface. Additionally, the conductivity of the film decreased with increasing bending cycle numbers; however, the film still exhibited a good conductivity and heating performances after repeated bending.

New Insights into Flexible Transparent Conductive Silver Nanowires Films

Flexible transparent conductive films (FTCFs) composed of silver nanowires (AgNWs) have become an important research direction because of their potential in flexible electronic devices. The optoelectronic properties of FTCFs composed of AgNWs of different lengths were evaluated in this study. AgNWs, with an average diameter of about 25 nm and length of 15.49-3.92 μm were obtained by a sonication-induced scission process. AgNW-FTCFs were prepared on polyethylene terephthalate substrates using a Meyer bar and then dried in the ambient environment. The sheet resistance, non-uniformity factor of the sheet resistance, the root mean square roughness, and haze of the FTCFs increased as the length of AgNWs decreased. The transmittance of the films increased slightly as the length of AgNWs increased. AgNWs with a length of 15.49 μm provided an AgNW-FTCF with excellent properties including haze of 0.95%, transmittance of 93.42%, and sheet resistance of 80.15 Ω∙sq-1, without any additional post-treatment of the film. This work investigating the dependence of the optoelectronic properties of AgNW-FTCFs on AgNW length provides design guidelines for development of AgNW-FTCFs.

Tailoring the Temperature Coefficient of Resistance of Silver Nanowire Nanocomposites and their Application as Stretchable Temperature Sensors

Body temperature is an important indicator of the health condition. It is of critical importance to develop a smart temperature sensor for wearable applications. Silver nanowire (AgNW) is a promising conductive material for developing flexible and stretchable electrodes. Here, a stretchable and breathable thermoresistive temperature sensor based on AgNW composites is developed, where a AgNW percolation network is encased in a thin polyimide film. The temperature coefficient of resistance of the AgNW network is tailored by modifying nanowire density and thermal annealing temperature. The temperature sensor is patterned with a Kirigami structure, which enables constant resistance under a large tensile strain (up to 100%). Demonstrated applications in monitoring the temperatures at biceps and knees using the stretchable temperature sensor illustrate the promising potential for wearable applications.

A Single-Crystalline Silver Plasmonic Circuit for Visible Quantum Emitters

Plasmonic waveguides are key elements in nanophotonic devices, serving as optical interconnects between nanoscale light sources and detectors. Multimode operation in plasmonic two-wire transmission lines promises important degrees of freedom for near-field manipulation and information encoding. However, highly confined plasmon propagation along gold nanostructures is typically limited to the near-infrared region due to ohmic losses, excluding all visible quantum emitters from plasmonic circuitry. We report on the top-down fabrication of complex plasmonic nanostructures in single-crystalline silver plates. We demonstrate the controlled remote excitation of a small ensemble of fluorophores by a set of waveguide modes and the emission of the visible luminescence into the waveguide with high efficiency. This approach opens up the study of a nanoscale light-matter interaction between complex plasmonic waveguides and a large variety of quantum emitters available in the visible spectral range.

Enhancement of the Conductivity and Uniformity of Silver Nanowire Flexible Transparent Conductive Films by Femtosecond Laser-Induced Nanowelding

In order to improve the performance of silver nanowire (AgNW) flexible transparent conductive films (FTCFs), including the conductivity, uniformity, and reliability, the welding of high repetition rate femtosecond (fs) laser is applied in this work. Fs laser irradiation can produce local enhancement of electric field, which induce melting at the gap of the AgNWs and enhance electrical conductivity of nanowire networks. The overall resistivity of the laser-welded AgNW FTCFs reduced significantly and the transparency changed slightly. Meanwhile, PET substrates were not damaged during the laser welding procedure in particular parameters. The AgNW FTCFs can achieve a nonuniformity factor of the sheet resistance as 4.6% at an average sheet resistance of 16.1 Ω/sq and transmittance of 91%. The laser-welded AgNW FTCFs also exhibited excellent reliability against mechanical bending over 10,000 cycles. The welding process may open up a new approach for improvement of FTCFs photoelectric property and can be applied in the fabrication of silver nanostructures for flexible optoelectronic and integration of functional devices.

Plasmonics with Metallic Nanowires

The purpose of this review is to introduce and present the concept of metallic nanowires as building-blocks of plasmonically active structures. In addition to concise description of both the basic physical properties associated with the electron oscillations as well as energy propagation in metallic nanostructures, and methods of fabrication of metallic nanowires, we will demonstrate several key ideas that involve interactions between plasmon excitations and electronic states in surrounding molecules or other emitters. Particular emphasis will be placed on the effects that involve not only plasmonic enhancement or quenching of fluorescence, but also propagation of energy on lengths that exceed the wavelength of light.

Using Electrospun AgNW/P(VDF-TrFE) Composite Nanofibers to Create Transparent and Wearable Single-Electrode Triboelectric Nanogenerators for Self-Powered Touch Panels

Self-powered sensors have attracted significant interest for individual wearable device operation. Here, transparent and wearable single-electrode triboelectric nanogenerators (SETENGs) with high power generation are created using electrospun Ag nanowires (AgNWs)/poly(vinylidenefluoride-cotrifluoroethylene) [P(VDF-TrFE)] composite nanofibers (NFs). The SETENGs generate an output power density of up to 217 W/m² with repetitive contact and separation from the surface of a latex glove. In electrospun P(VDF-TrFE) NFs, the crystalline β-phase is highly oriented by oxygen-containing functional groups on the surface of AgNWs, endowing the F-rich surface with high electron negativity and enabling efficient triboelectrification. Additionally, 80% transmittance at a light wavelength of 550 nm, mechanical stability, and durability after 10 000 cycles at 10% strain are confirmed by filling the NF pores with plasma desorption mass spectrometry. Our SETENG acts as an effective energy harvester by powering 45 light-emitting diodes and as an excellent real-time, self-powered touch panel.

High-Resolution and Large-Area Patterning of Highly Conductive Silver Nanowire Electrodes by Reverse Offset Printing and Intense Pulsed Light Irradiation

Conventional printing technologies such as inkjet, screen, and gravure printing have been used to fabricate patterns of silver nanowire (AgNW) transparent conducting electrodes (TCEs) for a variety of electronic devices. However, they have critical limitations in achieving micrometer-scale fine line width, uniform thickness, sharp line edge, and pattering of various shapes. Moreover, the optical and electrical properties of printed AgNW patterns do not satisfy the performance required by flexible integrated electronic devices. Here, we report a high-resolution and large-area patterning of highly conductive AgNW TCEs by reverse offset printing and intense pulsed light (IPL) irradiation for flexible integrated electronic devices. A conductive AgNW ink for reverse offset printing is prepared by carefully adjusting the composition of AgNW content, solvents, surface energy modifiers, and organic binders for the first time. High-quality and high-resolution AgNW micropatterns with various shapes and line widths are successfully achieved on a large-area plastic substrate (120 × 100 mm²) by optimizing the process parameters of reverse offset printing. The reverse offset printed AgNW micropatterns exhibit superior fine line widths (up to 6 μm) and excellent pattern quality such as sharp line edge, fine line spacing, effective wire junction connection, and smooth film roughness. They are post-processed with IPL irradiation, thereby realizing excellent optical, electrical, and mechanical properties. Furthermore, flexible OLEDs and heaters based on reverse offset printed AgNW micropatterns are successfully fabricated and characterized, demonstrating the potential use of the reverse offset printing for the conductive AgNW ink.

Binder-Free Graphene/Silver Nanowire Gel-Like Composite with Tunable Properties and Multifunctional Applications

To realize macroscopic utilization of the excellent properties of graphene, various forms of graphene assemblies have been investigated. Among them, the gel form assemblies show great advantages because of their shapeable and self-healable properties and facile and simple manufacturing processes. For the conventional gel-formed graphene assemblies, a relatively large content of binders including hydrophilic polymers, celluloses, or/and amorphous inorganic materials is necessary in achieving the gelation. However, these binders are electrically nonconductive and electrochemically inactive, which would weaken the favorable functionalities of the composite, and the potential advantages of graphene cannot be fully utilized. Herein, a binder-free silver nanowire (Ag-NW)/reduced graphene oxide (rGO) gel-like composite is designed and successfully fabricated by employing the ultralong Ag-NWs to enhance the hierarchical synergistic effects. The fabrication technique is highly efficient and repeatable, and the obtained composite is flexible, stretchable, and self-healable. Furthermore, the overall properties of the composite can be easily adjusted in a wide range by controlling the mass ratio between Ag-NW and rGO, which makes it multipurpose and suitable in different applications. Several demonstrations have been carried out, and some special performances including linear strain sensing range and rapid transformation from wet to dry state are found in this unique composite. This binder-free structure could also be expanded to other material systems, which may offer a valuable inspiration for the development of functional devices based on the nanocomposite.

Sandwich-Structured Silver Nanowire Transparent Conductive Films with 3H Hardness and Robust Flexibility for Potential Applications in Curved Touch Screens

A sandwich-structured bottom hard-coat/silver nanowire/top hard-coat (BHC/AgNW/THC) transparent conductive film (TCF) has been prepared by embedding the functional AgNW layer between two HC layers. The BHC/AgNW/THC TCFs show high scratch resistance with a hardness of 3H due to the enhanced adhesion to the substrate. In addition, the BHC/AgNW/THC TCFs exhibit a transmittance of 90.6% and a haze of 1% at 550 nm under a sheet resistance of 72 Ω/sq. Furthermore, highly enhanced long-term stability has been guaranteed by the HC layers due to their excellent gas barrier property. The amazing fact is that hard coating has little effect on the flexibility of AgNW films especially under extreme bending conditions and negligible resistance change could be observed after bending over thousands of times. Consequently, the greatly improved performance of BHC/AgNW/THC TCFs provided by employing hard coating layers paves the way for real-world applications of flexible AgNWs in vast areas that rigid indium tin oxide is not suitable.

Improved Stability of Metal Nanowires via Electron Beam Irradiation Induced Surface Passivation

Suppressing the corrosion of nanoscaled metal materials is a critical issue for various devices. Herein, we demonstrate the electron beam irradiation can be a simple and efficient method to realize silver/copper nanowires protection by transforming the original organic capping agents into dense carbonaceous shells. Single nanowire tests prove the significant stability improvement from 4 days to 20 days for silver nanowire and from 20 h to at least 1 week for copper nanowire. The comprehensive advantages such as solution/pollution-free and continuous process with high precision offer this method substantial potential applications in bottom-up assembled electronic and optoelectronic devices.

Ultrasensitive and Highly Compressible Piezoresistive Sensor Based on Polyurethane Sponge Coated with a Cracked Cellulose Nanofibril/Silver Nanowire Layer

With the rapid development of flexible wearable electronics, a piezoresistive sensor with low detection limit and wide strain sensing range turns out to be a great challenge for its application in this field. Here, a cracked cellulose nanofibril/silver nanowire (CA) layer-coated polyurethane (PU) sponge was acquired through a simple dip-coating process followed by precompression treatment. The electrical conductivity and mechanical property of the conductive CA@PU sponge could be effectively tuned through changing the dip-coating number. As a piezoresistive sensor, the sponge exhibited the capability of detecting both small and large motions over a wide compression strain range of 0-80%. Based on the "crack effect", the sensor possessed a detection limit as low as 0.2% and the gauge factor [GF, GF = (Δ R/ R₀)/ε, where Δ R, R₀, and ε represent the instantaneous resistance change, original resistance, and strain applied, respectively] was as high as 26.07 in the strain range of 0-0.6%. Moreover, the "contact effect" enabled the sensor to be applicable for larger strain, and the GF decreased first and then became stable with increasing compression strain. In addition, frequency- and strain-dependent sensing performances were observed, demonstrating that the sensor can respond reliably to different applied frequencies and strains. Furthermore, the sensor displayed exceptional stability, repeatability, and durability over 500 cycles. Finally, the sensor could be applicable for the detection of various human bodily motions, such as phonation, stamping, knee bending, and wrist bending. Most importantly, the sponge also exhibited great potential for the fabrication of artificial electronic skin. Herein, the conductive CA@PU sponge will undoubtedly promote the development of high-performance flexible wearable electronics.

Optical Properties of Submillimeter Silver Nanowires Synthesized Using the Hydrothermal Method

We report on the synthesis of long silver nanowires using the hydrothermal method, with H₂O₂ as the reducing agent. Our approach yields nanowires with an average diameter and length of about 100 nm and 160 µm, respectively, reaching the maximum length of 800 µm. Scanning electron microscopy (SEM) measurements revealed the presence of a thick, inhomogeneous poly(vinylpyrrolidone) (PVP) layer covering the nanowires, which with time becomes much more uniform, leading to well-defined extinction peaks in the ultraviolet-visible (UV-Vis) spectra. This change in morphology is evidenced also by the fluorescence enhancement behavior probed using protein complexes. Wide-field and confocal fluorescence microscopy measurements demonstrate strong, 10-fold enhancement of the protein emission intensity, accompanied by a reduction of the fluorescence decay time. In addition, for the aged, one-month-old nanowires, the uniformity of the intensity profile along them was substantially improved as compared with the as-synthesized ones. The results point towards the importance of the morphology of plasmonically active silver nanowires when considering their application in enhancing optical properties or achieving energy propagation over submillimeter distances.

Elastomer-Free, Stretchable, and Conformable Silver Nanowire Conductors Enabled by Three-Dimensional Buckled Microstructures

Many three-dimensional (3D) nanomaterial-based assemblies need incorporation with elastomers to attain stretchability-that also compromises their pristine advantages for functional applications. Here, we show the design of elastomer-free, highly deformable silver nanowire (AgNW) conductors through dip-coating AgNWs on a 3D polymeric scaffold and following a simple triaxial compression approach. The resulting 3D AgNW conductors exhibit good stability of resistance under multimodal deformation, such as stretching, compressing, and bending as well as comparable conductivity with those elastomer-based ones. Moreover, the buckled structures endow our 3D conductors with novel negative Poisson's ratio behavior, which can offer good comfortability to curvilinear surfaces. The combination of mechanical properties, conductive performance, and unique deformation characteristics can satisfy multiscale conformal mechanics with a soft, curvilinear human body.

Bioinspired Ultrasensitive and Stretchable MXene-Based Strain Sensor via Nacre-Mimetic Microscale "Brick-and-Mortar" Architecture

The development of wearable strain sensors with simultaneous large stretchability (strain >55%) and high sensitivity (gauge factor >100) remains a grand challenge to this day. Drawing on inspiration from nature, nacre has demonstrated outstanding mechanical properties, especially combining high strength and toughness, which is due in part to its delicate hierarchical layered architecture with rich interfacial interactions. We demonstrate that strain sensors based on this nacre-mimetic microscale "brick-and-mortar" architecture can simultaneously achieve ultrahigh sensitivity and large stretchability while performing well in linearity, reliability, long-term durability, and monotonicity. The bioinspired sensor demonstrated a gauge factor >200 over a range of working strains up to 83% and achieved a high gauge factor exceeding 8700 in the strain region of 76-83%. This successful combination of high sensitivity and large stretchability is attributed to (1) the microscale hierarchical architecture derived from the amalgamation of 2D titanium carbide (MXene) Ti₃C₂T _x/1D silver nanowire "brick" and poly(dopamine)/Ni²⁺ "mortar" and (2) the synergistic toughing effects from interfacial interactions of hydrogen and coordination bonding, layer slippage, and molecular chain stretching. The synergistic behavior of the "brick" and "mortar" allows for controlled crack generation for high sensitivity but can also dissipate considerable loading energy to promote the stepwise propagation of cracks while stretching, guaranteeing the significant comprehensive sensing performance. Moreover, this bioinspired strain sensor is employed to monitor human activities under different motion states to demonstrate its feasibility for wearable, full-spectrum human health and motion monitoring systems.

Wireless Real-Time Temperature Monitoring of Blood Packages: Silver Nanowire-Embedded Flexible Temperature Sensors

Real-time temperature monitoring of individual blood packages capable of wireless data transmission to ensure the safety of blood samples and minimize wastes has become a critical issue in recent years. In this work, we propose flexible temperature sensors using silver nanowires (NWs) and a flexible colorless polyimide (CPI) film integrated with a wireless data transmission circuit. The unique design of the temperature sensors was achieved by patterning Ag NWs using a three-dimensional printed mold and embedding the patterned Ag NWs in the CPI film (p-Ag NWs/CPI), which resulted in a flexible temperature sensor with electrical, mechanical, and temperature stability for applications in blood temperature monitoring. Indeed, a reliable resistance change of the p-Ag NWs/CPI was observed in the temperature range of -20 to 20 °C with a robust bending stability of up to 5000 cycles at 5 mm bending radius. Real-time and wireless temperature monitoring using the p-Ag NWs/CPI was demonstrated with the packages of rat blood. The result revealed that the stable and consistent temperature monitoring of individual blood packages could be achieved in a blood box, which was mainly attributed to the conformal attachment of the p-Ag NWs/CPI to different packages in a blood container.

Bright Stretchable Electroluminescent Devices based on Silver Nanowire Electrodes and High-k Thermoplastic Elastomers

Stretchable electroluminescent device is a compliant form of light-emitting device to expand the application areas of conventional optoelectronics on rigid wafers. Currently, practical implementations are impeded by the high operating voltage required to achieve sufficient brightness. In this study, we report the fabrication of an intrinsically stretchable electroluminescent device based on silver nanowire electrodes and high-k thermoplastic elastomers. The device exhibits a bright emission with a low driving voltage by using polar elastomer as a dielectric matrix of the electroluminescent layer. Highly stretchable silver nanowire electrodes contribute to the exceptional elasticity and durability of the device in spite of bending, stretching, twisting, puncturing, and cutting. Stretchable electroluminescent devices developed here may find potential uses in wearable displays, deformable lightings, and soft robotics.

Facile Synthesis of Silver Nanoparticles with High Antibacterial Activity

We report on a reverse microemulsion method for the synthesis of silver nanocrystals and examine their antibacterial activities. As the molar ratio of water to sodium bis(2-ethylhexyl) sulfosuccinate (AOT) increases to 25, a morphology transition from a sphere-like nanocrystal to a wire-like one was observed. For both the gram-negative and gram-positive bacteria, the wire-like silver nanocrystal showed higher antibacterial activities. We conclude that the morphology of silver nanocrystals dominates their antibacterial activity.

Human Skin-Inspired Electronic Sensor Skin with Electromagnetic Interference Shielding for the Sensation and Protection of Wearable Electronics

Increasingly serious electromagnetic radiation pollution puts higher demands on wearable devices. Electronic sensor skin capable of shielding electromagnetic radiation can provide extra protection in emerging fields such as electronic skins, robotics, and artificial intelligence, but combining the sensation and electromagnetic shielding performance together remains a great challenge. Here, inspired by the structure and functions of the human skin, a multifunctional electronic skin (M-E-skin) with both tactile sensing and electromagnetic radiation shielding functions is proposed. The tactile sensing of human skin is mimicked with irregular dermislike rough surfaces, and the electromagnetic shielding performance not available on natural skin is introduced by mimicking the ultraviolet electromagnetic radiation absorption of melanin in epidermis. The M-E-skin shows superior sensitivity (9.8 × 10⁴ kPa^-1 for the pressure range 0-0.2 kPa and 3.5 × 10³ kPa^-1 within 0.2-20 kPa), broad operating range (0-20 kPa), fast response and relaxation times (<62.5 ms), great pressuring-relaxing stability (10 kPa, 1000 cycles), low operating voltage (0.1 V), low power consumption (1.5 nW), and low detection limit (5 Pa). Besides, a broad range of electromagnetic wave (0.5-7.5 GHz) is shielded more than 99.66% by the M-E-skin. This work holds great potential to enlarge the application scope of current electronic skins.

Spray Deposition of Ag Nanowire⁻Graphene Oxide Hybrid Electrodes for Flexible Polymer⁻Dispersed Liquid Crystal Displays

We investigated the effect of different spray-coating parameters on the electro-optical properties of Ag nanowires (NWs). Highly transparent and conductive Ag NW–graphene oxide (GO) hybrid electrodes were fabricated by using the spray-coating technique. The Ag NW percolation network was modified with GO and this led to a reduced sheet resistance of the Ag NW–GO electrode as the result of a decrease in the inter-nanowire contact resistance. Although electrical conductivity and optical transmittance of the Ag NW electrodes have a trade-off relationship, Ag NW–GO hybrid electrodes exhibited significantly improved sheet resistance and slightly decreased transmittance compared to Ag NW electrodes. Ag NW–GO hybrid electrodes were integrated into smart windows based on polymer-dispersed liquid crystals (PDLCs) for the first time. Experimental results showed that the electro-optical properties of the PDLCs based on Ag NW–GO electrodes were superior when compared to those of PDLCs based on only Ag NW electrodes. This study revealed that the hybrid Ag NW–GO electrode is a promising material for manufacturing the large-area flexible indium tin oxide (ITO)-free PDLCs.

Micropatterning Silver Nanowire Networks on Cellulose Nanopaper for Transparent Paper Electronics

Transparent microelectrodes with high bendability are necessary to develop lightweight, small electronic devices that are highly portable. Here, we report a reliable fabrication method for transparent and highly bendable microelectrodes based on conductive silver nanowires (AgNWs) and 2,2,6,6-tetramethylpiperidine-1-oxy (TEMPO)-oxidized cellulose nanofibers (CNFs). The AgNW-based micropatterns were simply fabricated on glass via poly(ethylene glycol) photolithography and then completely transferred to transparent TEMPO-CNF nanopaper with high bendability via vacuum-assisted microcontact printing (μCP). The AgNW micropatterns were embedded in the surface layer of TEMPO-CNF nanopaper, enabling strong adhesion to the nanopaper substrate. The resulting AgNW micropatterns on the TEMPO-CNF nanopaper showed an optical transparency of 82% at 550 nm and a sheet resistance of 54 Ω/sq when the surface density of AgNWs was as low as 12.9 μg/cm². They exhibited good adhesion stability and excellent bending durability. After 12 peeling test cycles and 60 s sonication time, the sheet resistance of the AgNW networks embedded on TEMPO-CNF nanopaper increased by only ∼0.12 and ∼0.07 times, respectively. Furthermore, no significant change in electrical resistance was observed even after 3 bending cycles to nearly 90° and 500 cycles of 80% bending strain. Moreover, the AgNW patterns on TEMPO-CNF paper were successfully applied for constructing a transparent electric circuit as well as a solid-state electrochromic device. Overall, we proposed an effective way to fabricate AgNW micropatterns on transparent nanopaper, which can be expanded to various conductive materials for high-performance paper-based electronics.

Comprehensive Stability Improvement of Silver Nanowire Networks via Self-Assembled Mercapto Inhibitors

Instability of silver nanowire (AgNW) has been regarded as a major obstacle to its practical applications in optoelectrical devices as transparent electrodes. Physical barrier layers such as polymer, metal, and graphene have been generally employed to improve the stability of AgNW in previous study. Herein, we first report self-assembled organothiols as an inhibitor for AgNW to achieve an overall enhancement in antioxidation, antisulfidation, thermal stability, and anti-electromigration. The self-assembled monolayers (SAMs) of phenyl azoles, methoxy silane, and methyl alkane were formed on the surface of AgNW via Ag-S covalent bond as barrier layers which provided protective effects against corrosives (e.g., O₂, H₂S). In particular, the decoration of 2-mercaptobenzimidazole (MBI) offered the best resistance to H₂S and excellent stability under a high-temperature and high-humidity environment (85 °C and 85 RH %) for 4 months. Moreover, different SAMs exhibited a stabilizing or destabilizing effect on Plateau-Rayleigh instability of AgNW, which realized the tunability of degradation temperature of AgNWs, for example, increasing by ≥100 °C with MBI SAM or decreasing by ∼50 °C with octadecanethiol SAM compared with pristine AgNWs. Notably, the MBI-decorated AgNWs could survive at 400 °C which is by far the highest bearing temperature for solution-processed AgNW film. As a result, a transparent heater made of the MBI-AgNWs exhibited superior heating characteristics (higher working temperature and durability), as compared with the pristine AgNW-based heater. Our findings on the organothiols decoration not only provide a new paradigm in overall stability improvement of NW of noble metals but also show the potential in morphology controllability of metal NW.

On the Frequency Response of Nanostructured Thermoacoustic Loudspeakers

In this work, we investigate the thermal and acoustic frequency responses of nanostructured thermoacoustic loudspeakers. An opposite frequency dependence of thermal and acoustic responses was found independently of the device substrate (Kapton and glass) and the nanometric active film (silver nanowires and nm-thick metal films). The experimental results are interpreted with the support of a comprehensive electro-thermo-acoustic model, allowing for the separation of the purely thermal effects from the proper thermoacoustic (TA) transduction. The thermal interactions causing the reported opposite trends are understood, providing useful insights for the further development of the TA loudspeaker technology.

Highly Conducting Hybrid Silver-Nanowire-Embedded Poly(3,4-ethylenedioxythiophene):Poly(styrenesulfonate) for High-Efficiency Planar Silicon/Organic Heterojunction Solar Cells

Embedding nanowires, such as silver nanowires (AgNWs), in a transparent conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to enhance its conductivity is technologically important for improving the performances of devices comprising transparent conductive layers. Addition of nanowires in the highly conducting form of cosolvent (ethylene glycol) or mixed-cosolvent (ethylene glycol and methanol) modified PEDOT:PSS could change the nanowire structure and significantly alter the conductivity. Here, we report a simple method to embed AgNWs in PEDOT:PSS efficiently to improve its conductivity. By incorporating nanowires in the mixed cosolvent matrix prior to addition into PEDOT:PSS, this method preserves the structure of the nanowires while enabling conductivity enhancement. In contrast, the addition of AgNWs into cosolvent-premodified PEDOT:PSS leads to breaking of nanowires and conductivity impediment. The hybrid films with efficiently embedded AgNWs and mixed-cosolvent-modified PEDOT:PSS show a sheet resistance of 104 Ω/□, which is among the lowest ever reported for the as-deposited films, with conductivity enhancement of 33% relative to that of mixed-cosolvent-modified PEDOT:PSS. The resulting planar heterojunction solar cell (HSC) based on AgNW-embedded PEDOT:PSS exhibits a power conversion efficiency of greater than 15%. This demonstrates the importance of reducing sheet resistance by integrating nanowires into the PEDOT:PSS matrix as effective charge-transfer conduits interconnecting the highly conducting quinoid chains. The present approach to efficiently embed AgNWs in PEDOT:PSS could be readily extended to other nanowires or nanoparticles for improving the performance of PEDOT:PSS for applications in not just HSCs but indeed other electronic devices that require both transparent and highly conductive layers.