Ag Nanowire Films Research Articles

Ag nanowires: large-scale synthesis via a trace-salt-assisted solvothermal process and application in transparent electrodes

Ag nanowire (AgNW) films are receiving increasing attention as new transparent conductive films poised to replace indium tine oxide materials. However, coating of AgNW surfaces with polyvinylpyrrolidone (PVP) and other impurities during synthesis causes large contact resistance between the wires leading to low conductivities in the absence of additional treatments to fuse the overlapped AgNWs together. In the present work, we demonstrated a simple method to synthesize AgNWs by the reduction of AgNO3 using PVP as the reducing agent assisted by trace amounts of salts in ethanol. The shape and yield of the AgNWs depended significantly on the concentrations of these trace salts and on reaction temperatures. The silver nanowires were about 5–20 μm in length and showed a uniform diameter of about 70 nm. A detailed growth mechanism of the AgNWs has been proposed on the basis of the observations recorded by varying these synthesis parameters. Further, the AgNWs were used to form a transparent film, which without any additional treatments showed a sheet resistance of 10.4 Ω/sq and a transmittance of 81.9 % at 550 nm. The performance of the films was attributed to the trace amounts of residual impurities on the surface of the AgNWs and to the special V-shaped morphology of the wires prepared with the solvothermal process.

Photoluminescence via gap plasmons between single silver nanowires and a thin gold film

In this work, we investigate the one-photon photoluminescence from a system consisting of an Ag nanowire on an Au film with a ~6 nm dielectric spacer that supports a localized resonance known as the gap plasmon mode. Although the Ag nanowire and Au film exhibit weak photoluminescence on their own, the combined system produces an enhanced PL emission. Our analysis reveals that the strong PL emission in this system was due to the enhanced laser absorption in, and PL emission from Au, with the Ag nanowire acting as an efficient antenna. The PL due to the gap mode is sensitive to the polarization of the laser excitation with respect to the nanowire orientation, and shows a clear dipolar emission profile. PL emission wavelengths were found to depend only on the nanowire width, and independent of its length. These observations were supported by simulation results indicating that gap plasmons are excited by light polarized transverse to the nanowire length.

Direct two-phase interfacial self-assembly of aligned silver nanowire films for surface enhanced Raman scattering applications

Assembly of nanowires into ordered macroscopic structures has attracted great scientific interest in the past decade. In this work, we report on a rapid low-cost scalable oil–water (two-phase) interfacial self-assembly process for fabricating aligned Ag nanowire (AgNW) films on solid substrates. This process is much simpler than traditional Langmuir–Blodgett (LB) techniques and allows the assembly of one-dimensional Ag nanowires on any solid substrate without extra pretreatment of either the surface of silver nanowires or the solid substrate. The resultant aligned AgNW films can be used as robust surface-enhanced Raman scattering (SERS) substrates for chemical and biomolecular detection with highly uniform and repeatable SERS signals over the entire substrate. Sensitive and quantitative detection of the toxicant arsenic in drinking water using these AgNW films are subsequently presented to demonstrate potential applications for environmental pollutant analysis.

Ordering Ag nanowire arrays by a glass capillary: A portable, reusable and durable SERS substrate

Assembly of nanowires into ordered macroscopic structures with new functionalities has been a recent focus. In this Letter, we report a new route for ordering hydrophilic Ag nanowires with high aspect ratio by flowing through a glass capillary. The present glass capillary with well-defined silver nanowire films inside can serve as a portable and reusable substrate for surface-enhanced Raman spectroscopy (SERS), which may provide a versatile and promising platform for detecting mixture pollutions. By controlling the flow parameters of nanowire suspensions, initially random Ag nanowires can be aligned to form nanowire arrays with tunable density, forming cambered nanowire films adhered onto the inner wall of the capillary. Compared with the planar ordered Ag nanowire films by the Langmuir-Blodgett (LB) technique, the cambered nanowire films show better SERS performance.

Nanostructured Hybrid Transparent Conductive Films with Antibacterial Properties

Here, we demonstrate that the assembly of nanostructures with different dimensionalities yields "multicomponent hybrid" transparent conductive films (TCFs) with sheet resistance and optical transmittance comparable to that of indium tin oxide (ITO) films. It was shown that sheet resistance of single-component Ag nanowire (NW) films can be further decreased by introducing gold-decorated reduced graphene oxide (RG-O) nanoplatelets that bridge the closely located noncontacting metal NWs. RG-O nanoplatelets can act as a protective and adhesive layer for underneath metal NWs, resulting in better performance of hybrid TCFs compared to single-component TCFs. Additionally, these hybrid TCFs possess antibacterial properties, demonstrating their multifunctional characteristics that might have a potential for biomedical device applications. Further development of this strategy paves a way toward next generation TCFs composed of different nanostructures and characterized by multiple (or additional) functionalities.

Ag-nanowire films coated with ZnO nanoparticles as a transparent electrode for solar cells

We demonstrate that solution-processible silver-nanowire films coated with zinc-oxide-nanoparticles (ZnO-NPs) can be used as transparent electrodes in organic photovoltaic devices. The ZnO-NP coating acts as electron extraction layer and as encapsulating agent, protecting the wires from oxidation and improving their mechanical stability. Scanning photocurrent microscopy showed photocurrent generation to be more efficient at the active material surrounding the wires. Ultra-violet illumination as present in the solar spectrum was found to enhance photocurrent by improving the ZnO in-layer conductivity through the photoconductive effect. Inverted polythiophene:fullerene devices using ZnO-NP coated silver-nanowires or indium-tin-oxide as transparent electrode reached power conversion efficiencies of 2.4%.

Ordering of Disordered Nanowires: Spontaneous Formation of Highly Aligned, Ultralong Ag Nanowire Films at Oil–Water–Air Interface

AbstractOne‐dimensional nanomaterials and their assemblies attract considerable scientific interest in the physical, chemical, and biological fields because of their potential applications in electronic and optical devices. The interface‐assembly method has become an important route for the self‐assembly of nanoparticles, nanosheets, nanotubes, and nanorods, but the self‐assembly of ultralong nanowires has only been successful using the Langmuir–Blodgett approach. A novel approach for the spontaneous formation of highly aligned, ultralong Ag nanowire films at the oil–water–air interface is described. In this approach, the three‐phase interface directs the movement and self‐assembly process of the ultralong Ag nanowires without the effect of an external force or complex apparatus. The ordered films exhibit intrinsic large electromagnetic fields that are localized in the interstitials between adjacent nanowires. This new three‐phase‐interface approach is proven to be a general route that can be extended to self‐assemble other ultralong nanowires and produce ordered films.