Solution-processed Silver Nanowire Research Articles

One-Step Synthesis of Graphene-Covered Silver Nanowires with Enhanced Stability for Heating and Strain Sensing.

Solution-processed silver nanowire (AgNW) networks have been considered as promising electrode candidates for next-generation electronic devices. However, they suffer from poor thermal and electrical stability and low mechanical properties, hindering their practical applications. In this work, graphene nanosheets are successfully introduced into AgNW via a facile one-step solvothermal process. Benefiting from increased conductive paths, the resultant AgNW/graphene films exhibit high electrical conductivity. More importantly, the interlocking NW morphology can be maintained under high temperature and applied voltage due to suppressed Ag migration, which is enabled by the introduction of graphene. This feature leads to enhanced thermal and electrical stability, making them suitable for use as transparent heaters. Furthermore, the composite films present excellent mechanical performance, and negligible resistance change is observed after 10 000 repeated bending cycles. To demonstrate their feasibility toward sensor applications, sandwiched strain sensors are designed, which can endure larger tensile strains and show higher sensitivity and repeatability compared with pure AgNW-based device. Furthermore, various hand gestures can be easily recognized by the resultant sensors based on unique combinations of sensing response. This work not only provides a low-cost method to realize large-scale synthesis of AgNW/graphene composites but also offers guidance to prepare high-performance electrodes for advanced electronics.

Conformal Encapsulation of Silver Nanowire Transparent Electrodes by Nanosized Reduced Graphene Oxide Leading to Improved All-Round Stability.

Solution-processed silver nanowire (AgNW) networks are promising as next-generation transparent conductive electrodes due to their excellent optoelectronic properties, mechanical flexibility, as well as low material and processing costs. However, AgNWs are prone to thermally induced fragmentation and chemical degradation, necessitating a conformal protective coating typically achieved by low-throughput methods such as sputtering or atomic layer deposition. Herein, we report a facile all-solution-based approach to synthesize a conformally coated AgNW network by nanosized reduced graphene oxide R(nGO). In this method, probe ultrasonication is used to obtain nanosized GO, which is coated on AgNWs by a layer-by-layer approach and then chemically treated to form R(nGO)/AgNW. We show that our transparent electrode has excellent transmittance (85-92%) and sheet resistance (17.5 Ω/sq), combined with outstanding thermal and electrothermal stability, thanks to the conformal nature of the R(nGO) film, and demonstrate its use as a transparent heater with a high maximum temperature. This, in conjunction with improved long-term chemical and mechanical bending stability of R(nGO)/AgNW, indicates that our newly developed process represents an effective and low-cost strategy to improve the overall operational resilience of metal nanowire-based transparent conductive electrodes.

Scalable Solution-Processed Fabrication Approach for High-Performance Silver Nanowire/MXene Hybrid Transparent Conductive Films.

The transparent conductive films (TCFs) based on silver nanowires are expected to be a next-generation electrode for flexible electronics. However, their defects such as easy oxidation and high junction resistance limit its wide application in practical situations. Herein, a method of coating Ti3C2Tx with different sizes was proposed to prepare silver nanowire/MXene composite films. The solution-processed silver nanowire (AgNW) networks were patched and welded by capillary force effect through the double-coatings of small and large MXene nanosheets. The sheet resistance of the optimized AgNW/MXene TCFs was 15.1 Ω/sq, the optical transmittance at 550 nm was 89.3%, and the figure of merit value was 214.4. Moreover, the AgNW/MXene TCF showed higher stability at 1600 mechanical bending, annealing at 100 °C for 50 h, and exposure to ambient air for 40 days. These results indicate that the novel AgNW/MXene TCFs have a great potential for high-performance flexible optoelectronic devices.

All solution-processed silver nanowires composite silica nanospheres antireflection structure with synergetic optoelectronic performance

The silver nanowires/SNSs AR composite TCFs have demonstrated the synergetic effect on optoelectronic performance via a facile solution method, reaching sheet resistance of 49.43 Ω sq−1 dropped by 8.66% and transmittance of 99.84% increased by 6.94%.

Influence of thermal annealing of Ag NWs/AZO composite films on behavior of Ag NWs/AZO-P3HT photodetectors

Solution-processed silver nanowires (Ag NWs)/AZO composite films were deposited on indium-free transparent conductive layers to yield hybrid photo-diodes. In this study, high-quality Ag NWs/AZO films were prepared by simple and controllable annealing process at 340 °C under nitrogen atmosphere instead of low annealing temperature used previously. P-type polymer poly-3-hexylthiophene-2,5 -diyl (P3HT) was then spin-coated on Ag NWs/AZO top to form p–n junction. Devices annealed under nitrogen showed significant improvement in rectification ratios when compared to those annealed under air at low temperature. The proposed method improved p–n junction diode behavior through tuning defect properties of Ag NWs/AZO by annealing. Ag NWs/AZO photodiode devices exhibited high on/off ratio reaching ∼8 × 103 using Ag NWs/AZO-340 when compared to ∼4 × 102 obtained with Ag NWs/AZO-200. The solution processed indium free Ag NWs/AZO composite film demonstrated superior performance as transparent electrodes, promising for reliable hybrid photodiodes in practical sensors. These findings look promising for simple and competitive detection of defect in Ag NWs/AZO for better future applications in optoelectronics.

Solution Process Fabrication of Silver Nanowire Composite Transparent Conductive Films with Tunable Work Function

Solution processed silver nanowire transparent conductive films (AgNW TCFs) have attracted substantial attention for various devices, and optoelectrical properties, surface roughness and work function are major issues affecting commercial applications. In this work, work function tunable AgNW-metal oxide composite TCFs (AgNW composite TCFs) were fabricated by filling AgNW networks with ZnO and Au/MoO3 thin films respectively. The introduction of nanoparticle constructed ZnO thin film as an electron transport layer decreases the work function from 3.82 eV of pristine AgNW TCFs to 2.76 eV due to the charges transport between AgNWs and ZnO nanoparticles, while the Au/MoO3 thin film as a hole injection layer increases the work function to 4.46 eV. The work function tunable AgNW composite TCFs show excellent optoelectronic properties with a sheet resistance of 17 Ω/sq and a transmittance of about 90%. Conductive metal oxides and metal nanoparticles filling the holes of AgNW networks improve the rough surface, uneven electronic field and chemical durability especially for better operating time and stability of organic optoelectrical devices, and provide a simple strategy for regulating the performance of AgNW TCFs.

Sol⁻Gel-Processed Organic⁻Inorganic Hybrid for Flexible Conductive Substrates Based on Gravure-Printed Silver Nanowires and Graphene.

In this study, an organic–inorganic (O–I) nanohybrid obtained by incorporating an alkoxysilane-functionalized amphiphilic polymer precursor into a SiO2–TiO2 hybrid network was successfully utilized as a buffer layer to fabricate a flexible, transparent, and stable conductive substrate for solution-processed silver nanowires (AgNWs) and graphene under ambient conditions. The resulting O–I nanohybrid sol (denoted as AGPTi) provided a transmittance of the spin-coated AgNWs on an AGPTi-coated glass of 99.4% and high adhesion strength after a 3M tape test, with no visible changes in the AgNWs. In addition, AGPTi acted as a highly functional buffer layer, absorbing the applied pressure between the conductive materials, AgNWs and graphene, and rigid substrate, leading to a significant reduction in sheet resistance. Furthermore, gravure-printed AgNWs and graphene on the AGPTi-based flexible substrate had uniform line widths of 490 ± 15 and 470 ± 12 µm, with 1000-cycle bending durabilities, respectively.

Fabrication of flexible indium tin oxide-free polymer solar cells with silver nanowire transparent electrode

Flexible indium tin oxide (ITO)-free poly(3-hexylthiophene):[6,6]-phenyl C61-butyric acid methyl ester (P3HT:PC61BM) solar cells with a spin-coated silver nanowire transparent electrode are demonstrated. The solution-processed silver nanowire thin film not only exhibits high transmission (∼87%), but also shows low sheet resistance Rs (∼25 Ω/sq). For solar cells with a conventional structure, the power conversion efficiency (PCE) of devices based on silver nanowires can reach around 2.29%. For the inverted structure, the PCE of devices can reach 3.39%. Conventional and inverted flexible ITO-based P3HT:PC61BM solar cells are also fabricated as a reference for comparison. For both types of solar cells, the PCE of ITO-free devices is very close that of an ITO-based polymer solar cell.

Communication—Fabrication of Imprinted ITO-Free Perovskite Solar Cells

Solution-processed silver nanowire (AgNW) thin films were designed to function as transparent electrode to replace indium tin oxide (ITO) electrode. Various times spin-coated AgNW films on substrate were fabricated and optimized according to transmission and sheet resistance Rs of electrode film. The optimized solution-processed AgNWs were further transferred and imprinted on flexible substrate (PEN) which can improve elastic modulus and mechanical properties of the electrode. Moreover, the modified AgNW electrode will possess strong endurance ability against resonant cleaning process and preprocess work. The power conversion efficiency (PCE) of flexible ITO-free perovskite solar cells based on AgNW electrode can reach 9.15%.

Highly transparent and thermal-stable silver nanowire conductive film covered with ZnMgO by atomic-layer-deposition

Solution-processed silver nanowires (AgNWs) have been considered as a promising material for next generation flexible transparent conductive electrodes. However AgNWs films have several intrinsic drawbacks, such as thermal stability and storage stability. Herein, we demonstrate a laminated ZnO/MgO (ZnMgO, ZMO) as a protective layer on the AgNWs films using atomic layer deposition (ALD). The fabricated films exhibited a low sheet resistance of 16 Ω/sq with high transmittance of 91% at 550 nm, an excellent thermal stability and bending property. The ZMO film grows perpendicularly on the surface of the AgNWs, making a perfect coverage of bulk silver nanowires and junction, which can effectively prompt the electrical transport behavior and enhance stability of the silver nanowires network.

Cu(In,Ga)Se2 thin film solar cells with solution processed silver nanowire composite window layers: Buffer/window junctions and their effects

We quantitatively and analytically investigate the properties of buffer/window junctions and their effects on the energy band alignment and the current-voltage characteristics of Cu(In,Ga)Se2 (CIGS) thin film solar cells with solution processed silver nanowire (AgNW) composite window layers. AgNWs are generally embedded in a moderately conductive matrix layer to ensure lateral collection efficiency of charge carriers photogenerated in the lateral gaps present between AgNWs. Studies on the junctions between a buffer and AgNW-composite window layers and their effects on the performances of CIGS thin film solar cells have seldom been addressed. Here, we show that solution processed AgNW-composite window layers could induce defect states at the buffer/window interface, resulting in poor energy band alignment impeding carrier transport in the solar cells. On the basis of our analysis, we suggest an analytical expression of nmatrixDi2≥3.46×10−5ε cm to avoid losses in the power conversion efficiency of the solar cells. nmatrix is the carrier concentration in a matrix layer embedding AgNWs, Di is the negative defect density at the buffer/window interface, and ε is the relative dielectric constant of the matrix layer embedding AgNWs.

Solution-processed Ag-nanowire/ZnO-nanoparticle composite transparent electrode for flexible organic solar cells

This paper demonstrates a hybrid transparent electrode composed of a solution-processed silver-nanowire (AgNW) film coated by zinc oxide nanoparticles (ZnO-NPs) acting as a modified buffer layer. The effect of the ZnO-NPs’ coating ratio on the performances of indium tin oxide (ITO)-free organic solar cells (OSCs) has been systematically investigated. The optimized ITO-free OSCs achieved a power conversion efficiency (PCE) of 2.85%, while flexible OSCs using the AgNW/ZnO-NP composite transparent electrode grown on a polyethylene terephthalate (PET) substrate showed a PCE of 2.2%.

Working from Both Sides: Composite Metallic Semitransparent Top Electrode for High Performance Perovskite Solar Cells.

We report herein perovskite solar cells using solution-processed silver nanowires (AgNWs) as transparent top electrode with markedly enhanced device performance, as well as stability by evaporating an ultrathin transparent Au (UTA) layer beneath the spin-coated AgNWs forming a composite transparent metallic electrode. The interlayer serves as a physical separation sandwiched in between the perovskite/hole transporting material (HTM) active layer and the halide-reactive AgNWs top-electrode to prevent undesired electrode degradation and simultaneously functions to significantly promote ohmic contact. The as-fabricated semitransparent PSCs feature a Voc of 0.96 V, a Jsc of 20.47 mA cm(-2), with an overall PCE of over 11% when measured with front illumination and a Voc of 0.92 V, a Jsc of 14.29 mA cm(-2), and an overall PCE of 7.53% with back illumination, corresponding to approximately 70% of the value under normal illumination conditions. The devices also demonstrate exceptional fabrication repeatability and air stability.

Fully solution-processed transparent electrodes based on silver nanowire composites for perovskite solar cells.

We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ∼80% at 550 nm and sheet resistance of 18 Ω sq(-1). Perovskite solar cells fabricated using a fully solution-processed transparent conductive electrode, Au/spiro-OMeTAD/CH3NH3PbI3 + m-Al2O3/ZnO/ITO/AgNW/ITO, exhibited a power conversion efficiency of 8.44% (comparable to that of the FTO/glass-based counterpart at 10.81%) and were stable for 30 days in ambient air. Our results demonstrate the feasibility of using AgNWs as a transparent bottom electrode in perovskite solar cells produced by a fully printable process.

Silver Nanowire Top Electrodes in Flexible Perovskite Solar Cells using Titanium Metal as Substrate.

Flexible perovskite solar cells (FPSCs) have various applications such as wearable electronic textiles and portable devices. In this work, we demonstrate FPSCs on a titanium metal substrate employing solution-processed silver nanowires (Ag NWs) as the top electrode. The Ag NW electrodes were deposited on top of the spiro-MeOTAD hole transport layer by a carefully controlled spray-coating method at moderate temperatures. The power conversion efficiency (PCE) reached 7.45 % under AM 1.5 100 mW cm(-2) illumination. Moreover, the efficiency for titanium-based FPSCs decreased only slightly (by 2.6 % of the initial value) after the devices were bent 100 times. With this and other advances, fully solution-based indium-free flexible photovoltaics, advantageous in terms of price and processing, have the potential to be scaled into commercial production.

Highly Robust Silver Nanowire Network for Transparent Electrode.

Solution-processed silver nanowire networks are one of the promising candidates to replace a traditional indium tin oxide as next-generation transparent and flexible electrodes due to their ease of processing, moderate flexibility, high transparency, and low sheet resistance. To date, however, high stability of the nanowire networks remains a major challenge because the long-term usages of these electrodes are limited by their poor thermal and chemical stabilities. Existing methods for addressing this challenge mainly focus on protecting the nanowire network with additional layers that require vacuum processes, which can lead to an increment in manufacturing cost. Here, we report a straightforward strategy of a sol-gel processing as a fast and robust way to improve the stabilities of silver nanowires. Compared with reported nanoparticles embedded in nanowire networks, better thermal and chemical stabilities are achieved via sol-gel coating of TiO2 over the silver nanowire networks. The conformal surface coverage suppressed surface diffusion of silver atoms and prevented chemical corrosion from the environment. These results highlight the important role of the functional layer in providing better thermal and chemical stabilities along with improved electrical properties and mechanical robustness. The silver nanowire/TiO2 composite electrodes were applied as the source and drain electrodes for In2O3 thin-film transistors (TFTs) and the devices exhibited improved electrical performance annealed at 300 °C without the degradation of the electrodes. These key findings not only demonstrated a general and effective method to improve the thermal and chemical stabilities of metal nanowire networks but also provided a basic guideline toward rational design of highly efficient and robust composite electrodes.

Silver Nanowire-Conducting Polymer-ITO Hybrids for Flexible and Transparent Conductive Electrodes with Excellent Durability.

PSS) and/or ITO are introduced. The optical and electrical properties of the AgNW films combined with PSS, ITO, or both of them were systematically examined. Among the films, the AgNW-PEDOT:PSS-ITO hybrid film exhibits a high transmittance (88%) and a low sheet resistance (44 Ω sq(-1)) with a small haze (1.9%). Moreover, the hybrid films show excellent durability to a variety of environmental stresses. By virtues of the high performance and durability, it is believed that the AgNW-PEDOT:PSS-ITO hybrid electrodes are highly suitable for practical use.

High-performance semitransparent perovskite solar cells with solution-processed silver nanowires as top electrodes

In this work, we report efficient semitransparent perovskite solar cells using solution-processed silver nanowires (AgNWs) as top electrodes. A thin layer of zinc oxide nanoparticles is introduced beneath the AgNWs, which fulfills two essential functionalities: it ensures ohmic contact between the PC60BM and the AgNWs and it serves as a physical foundation that enables the solution-deposition of AgNWs without causing damage to the underlying perovskite. The as-fabricated semitransparent perovskite cells show a high fill factor of 66.8%, Voc = 0.964 V, Jsc = 13.18 mA cm(-2), yielding an overall efficiency of 8.49% which corresponds to 80% of the reference devices with reflective opaque electrodes.

Fully printed organic tandem solar cells using solution-processed silver nanowires and opaque silver as charge collecting electrodes

Efficient, fully-printed organic tandem solar cells are realized by introducing solution-processed silver nanowires and opaque silver as charge collecting electrodes.

Performance enhancement of metal nanowire-based transparent electrodes by electrically driven nanoscale nucleation of metal oxides.

Solution-processed silver nanowire (AgNW) electrodes have been considered to be promising materials for next-generation flexible transparent conductive electrodes. Despite the fact that a single AgNW has extremely high conductivities, the high junction resistance between nanowires limits the performance of the AgNW matrix. Therefore, post-treatments are usually required to approach better NW-NW contact. Herein, we report a novel linking method that uses joule heating to accumulate sol-gel ZnO near nanowire junctions. The nanoscale ZnO nucleation successfully restrained the thermal instability of the AgNW under current injection and acted as an efficient tightening medium to realize good NW-NW contacts. A low process temperature (<50 °C), and thus low energy consumption, are required for ZnO nucleation. This made the use of substrates with very low operating temperatures, such as PET and PEN, feasible. The optimized AgNW transparent conductive electrodes (TCE) fabricated using this promising linking method exhibited a low sheet resistance (13 Ω sq(-1)), a high transmission (92% at 550 nm), a high figure of merit (FOM; up to σDC/σOp = 340) and can be applied to wide range of next-generation flexible optoelectronic devices.