Ag NWs Research Articles

Toward sustainable optoelectronics: solution-processed quantum dot photodetector fabrication using a surgical blade

Fabrication of optoelectronic devices relies on expensive, energy-consuming conventional tools including chemical vapor deposition, lithography, and metal evaporation. Furthermore, the films used in these devices are usually deposited at elevated temperatures (>300 ° C) and under high vacuum, which necessitate further restrictions on the device fabrication. Developing an alternative technology would contribute to the efforts on achieving a sustainable optoelectronics technology. Keeping this in our focus, here we present a simple technique to fabricate visible photodetectors (PDs). These fully solution-processed and transparent metal-semiconductor-metal (MSM) PDs employ silver nanowires (Ag NW) as the transparent electrodes replacing the indium-tin-oxide (ITO) commonly used in optoelectronic devices. By repeatedly spin coating Ag NWs on a glass substrate followed by the coating of zinc oxide nanoparticles, we obtained a highly conductive transparent electrode reaching a sheet resistance of 95 Ω / □ as measured by the four-probe method. Optical spectroscopy revealed that the transmittance of the Ag NW-ZnO films was 84% at 450 nm while the transmittance of the ITO films was 90% at the same wavelength. Following the formation of the conductive film, we scratched it using a heated surgical blade to open a gap. The scanning electron microscope images indicate that a gap of ∼30 μm is opened forming an insulating line. As the active layer, we drop-casted red-emitting CdSe/ZnS core-shell quantum dots (QDs) onto this gap to form a MSM PD. These visible QD-based PDs exhibited responsivities and detectivities up to 8.5 mA / W and 0.95 × 109 Jones, respectively at a bias voltage of 5 V and wavelength of 650 nm. These proof-of-concept PDs show that the environmentally friendly, low-cost, and energy-saving technique presented here can be an alternative to conventional, high-cost, and energy-hungry techniques while fabricating photoconductive devices.

High-performance flexible dual-function networks based on MXene hybrid film for human–machine interaction

Flexible multifunctional devices can be used in many fields, but it needs to solve the limitations of their integration and mutual interference, which limits their practical applications. Therefore, it is urgent to develop a flexible sensor that can sense multiple signals at the same time and apply it to human physiological monitoring in real-time. Herein, we developed a flexible dual function sensor which used Ti3C2T x MXene/Ag nanowires (Ag NWs)/tissue hybrid film as the sensing materials. The flexible devices exhibit two types of sensing, including high-performance pressure sensing with a high sensitivity and fast response speed, and high-performance humidity sensing with wide detection range of relative humidity. These new functions enable the device to monitor human motion information and human–machine interaction in a personalized way like an electronic skin. The synthesis of Ti3C2T x MXene/Ag NWs/tissue hybrid film provides a material suitable for large-scale preparation for the development of wearable electronic devices with high performance and high integration.

A wearable self-powered fire warning e-textile enabled by aramid nanofibers/MXene/silver nanowires aerogel fiber for fire protection used in firefighting clothing

Firefighting clothing is an essential equipment that can provide safety personal protective from all kinds of thermal hazards and prevent burn injuries for firefighters. However, it is still a challenge to develop high fire safety firefighting clothing with an early fire alarm response before protective clothing malfunctional in extreme fire conditions. Herein, a wearable self-powered early fire warning e-textile (MAA e-textile) enabled by Ti3C2Tx MXene/silver nanowires (Ag NWs)/aramid nanofibers (ANFs) aerogel fiber was fabricated via wet spinning technique. The resulting self-powered fire warning MAA e-textile can be integrated into firefighting clothing to achieve wide-range temperature sensing at 100–400 °C based on a linear relationship between thermoelectric voltage and temperature due to thermoelectric characteristic of MXene, which could alert firefighters to evacuate timely before protective clothing was damaged. The bridging connection between Ag NWs and MXene nanosheets enable 30 wt% MAA e-textile to possess rapidly and repeatedly fire warning performance in 1.6 s when being burned. Meanwhile, because of the synergistic carbonization between MXene and ANFs, 30 wt% MAA e-textile exhibited excellent flame retardancy, whose peak heat release rate was significantly decreased by 80 % compared with ANFs aerogel fiber. Moreover, a self-powered rescue location system enabled by MAA e-textile-based triboelectric nanogenerator is further assembled to rescue trapped firefighters by providing correct escape routes. This work provided a facile approach into the fabrication and application of wearable self-powered early fire warning e-textile in firefighting clothing to ensure the operation safety of firefighters during firefighting process.

Large area AZO/Ag NWs/AZO transparent conductive film based on the Dip-coating method

Metal nanowires have received much attention when considering new promising transparent conductors to replace the cost rising tin-doped indium oxide (ITO). Here, we successfully obtained AZO/Ag NWs/AZO transparent conductive films (TCFs) with a large area (∼150 cm2) by dip-coating. It is found that the resistance and the transmittance of TCFs decrease with increasing Ag NWs immersion-coating time. A maximum figure of merit (ΦTC) value was achieved when the Ag NWs 5 cycles: ΦTC ∼ 3.05 × 10−3 Ω−1 (T:75.6 %, R: 20 Ω). The TCFs prepared by simple solution dip-coating method has superior optical and electric properties. This work provides a simple and effective way to develop large area, low-cost, and high-performance TCFs, and is expected to be applied to various optoelectronic devices (such as solar cells and photodetectors) as an alternative electrode.

Flexible, robust, sandwich structure polyimide composite film with alternative MXene and Ag NWs layers for electromagnetic interference shielding

The design and fabrication of electromagnetic interference shielding films with a novel structure to eliminate undesirable electromagnetic pollution is an important research direction. However, it is still a challenge to combine and organize nanofillers in different dimensions into the structured network in polymer-based electromagnetic interference (EMI) shielding composites. In this work, a sandwich structure polyimide (PI) composite film with alternative 2D-MXene network and 1D-Silver nanowires (Ag NWs) network was prepared through the “electrospinning-immersion-hot pressing” method. With the increase of Ag NWs content, the EMI shielding effectiveness (SE) gradually increases while maintaining good flexibility and mechanical robustness. The EMI SE and the tensile strength of 150 μm thick sandwich composite film can reach up to 79.54 dB and 39.82 MPa, respectively. The prepared flexible and robust PI composite film with a sandwich structure has high EMI SE with less metal content, which can provide guidelines for the development of high-performance EMI polymeric films with potentials in wearable devices and equipment.

Early-stage oral cancer diagnosis by artificial intelligence-based SERS using Ag NWs@ZIF core-shell nanochains.

Surface-enhanced Raman spectroscopy (SERS) has great potential in the early diagnosis of diseases by detecting the changes of volatile biomarkers in exhaled breath, because of its high sensitivity, rich chemical molecular fingerprint information, and immunity to humidity. Here, an accurate diagnosis of oral cancer (OC) is demonstrated using artificial intelligence (AI)-based SERS of exhaled breath in plasmonic-metal organic framework (MOF) nanoparticles. These plasmonic-MOF nanoparticles were prepared using a zeolitic imidazolate framework coated on Ag nanowires (Ag NWs@ZIF), which offers Raman enhancement from the plasmonic nanowires and gas enrichment from the ZIF shells. Then, the core-shell nanochains of Ag NWs@ZIF prepared with 0.5 mL Ag NWs were selected to capture gaseous methanethiol, which is a tumor biomarker, from the exhalation of OC patients. The substrate was used to collect a total of 400 SERS spectra of exhaled breath of simulated healthy people and simulated OC patients. The artificial neural network (ANN) model in the AI algorithm was trained with these SERS spectra and could classify them with an accuracy of 99%. Notably, the model predicted OC with an area under the curve (AUC) of 0.996 for the simulated OC breath samples. This work suggests the great potential of the combination of breath analysis and AI as a method for the early-stage diagnosis of oral cancer.

Continuous Patterning of Silver Nanowire-Polyvinylpyrrolidone Composite Transparent Conductive Film by a Roll-to-Roll Selective Calendering Process

The roll-to-roll (R2R) continuous patterning of silver nanowire-polyvinylpyrrolidone (Ag NW-PVP) composite transparent conductive film (cTCF) is demonstrated in this work by means of slot-die coating followed by selective calendering. The Ag NWs were synthesized by the polyol method, and adequately washed to leave an appropriate amount of PVP to act as a capping agent and dispersant. The as-coated Ag NW-PVP composite film had low electronic conductivity due to the lack of percolation path, which was greatly improved by the calendering process. Moreover, the dispersion of Ag NWs was analyzed with addition of PVP in terms of density and molecular weight. The excellent dispersion led to uniform distribution of Ag NWs in a cTCF. The continuous patterning was conducted using an embossed pattern roll to perform selective calendering. To evaluate the capability of the calendering process, various line widths and spacing patterns were investigated. The minimum pattern dimensions achievable were determined to be a line width of 0.1 mm and a line spacing of 1 mm. Finally, continuous patterning using selective calendering was applied to the fabrication of a flexible heater and a resistive touch sensing panel as flexible electronic devices to demonstrate its versatility.

Highly Conductive and Compliant Silver Nanowire Nanocomposites by Direct Spray Deposition

The silver nanowire (Ag NW)/elastomer nanocomposite represents a prototypical form of a compliant conductor for flexible and stretchable electronic devices. The widespread implementations are currently hindered by the complicated procedures to effectively disperse Ag NWs into elastomer matrices. In this study, we report a facile and scalable coating process to create Ag NW nanocomposites on various flexible/stretchable substrates. As-synthesized Ag NWs from the high-yield polyol-reduction approach are homogeneously dispersed into a variety of dilute elastomer solutions, thereby enabling direct spray deposition into highly compliant conductors. The as-prepared nanocomposite exhibits excellent conductivity (∼11,000 S/cm) and high deformability to 100% strain. The stable electrical properties are largely retained under repetitive mechanical manipulations including stretching, bending, and folding. The patterned features of conductive nanocomposites are conveniently accessed using shadow masks or selective laser ablation. The practical suitability is demonstrated by the successful implementations of a stretchable sensing patch and a flexible light-emitting diode display.

Comparative Study on Preparation Methods for Transparent Conductive Films Based on Silver Nanowires.

Silver nanowires, which have high optoelectronic properties, have the potential to supersede indium tin oxide in the field of electrocatalysis, stretchable electronic, and solar cells. Herein, four mainstream experimental methods, including Mayer-rod coating, spin coating, spray coating, and vacuum filtration methods, are employed to fabricate transparent conductive films based on the same silver nanowires to clarify the significance of preparation methods on the performance of the films. The surface morphology, conductive property, uniformity, and flexible stability of these four Ag NW-based films, are analyzed and compared to explore the advantages of these methods. The transparent conductive films produced by the vacuum filtration method have the most outstanding performance in terms of surface roughness and uniformity, benefitting from the stronger welding of NW-NW junctions after the press procedure. However, limited by the size of the membrane and the vacuum degree of the equipment, the small-size Ag films used in precious devices are appropriate to obtain through this method. Similarly, the spin coating method is suited to prepare Ag NWs films with small sizes, which shows excellent stability after the bending test. In comparison, much larger-size films could be obtained through Mayer-rod coating and spray coating methods. The pull-down speed and force among the Mayer-rod coating process, as well as the spray distance and traveling speed among the spray coating process, are essential to the uniformity of Ag NW films. After being treated with NaBH4 and polymethyl methacrylate (PMMA), the obtained Ag NW/PMMA films show great potential in the field of film defogging due to the Joule heating effect. Taken together, based on the advantages of each preparation method, the Ag NW-based films with desired size and performances are easier to prepare, meeting the requirements of different application fields.

Therapeutic effect and mechanism of silver nanowires on radiation pneumonitis by inhibiting the excessive inflammatory response of epithelial cells

Three new silver nanowire (Ag NW) samples with different diameters and lengths were synthesized by the polyol synthesis method. The diameter and length of Ag NWs 1–3 with high yield and purity were regulated by changing the amount of Fe3+ ions at 140 °C, producing new synthesized methods in designing and obtaining Ag NWs with desired size and morphology. Samples Ag NWs 1–3 were fully characterized by scanning electron microscopy and powder X-ray diffraction. ELISA was further conducted to measure the release of TNF-α and TGF-β1 from epithelial cells after Ag NWs 1–3 treatment. Then, real time RT-PCR was performed, and the activation of AMPK signaling pathway in epithelial cells was evaluated.

Treatment Activity of Silver Nanowires on Senile Cataract by Inhibiting the Apoptosis of Lens Epithelial Cells Induced by High Glucose

In this publication, three as-synthesized silver nanowires (Ag NWs) with high purity and yield were prepared via polyol synthesis method. The Ag NWs were characterized by scanning electron microscopy and powder X-ray diffraction. The effects of crystallization time and control agents were also explored, providing an effective method to design and synthesize Ag NWs. In addition, the biological activity of the Ag NWs for senile cataract therapy was evaluated, and the related mechanism was explored. Real-time polymerase chain reaction was conducted to measure the relative expression levels of the apoptosis-related genes p53 and BCL-2 in the mRNA level. Enzyme-linked immunosorbent assay was carried out, and TGF-β2 content was determined.

Clinical application study of silver nanowires combined with a synergistic leukocyte filter in cardioplegia after anesthesia

In this report, silver nanowire (Ag NW) samples of different sizes have been successfully synthesized by using the new polyol synthesis method. A new type of polyol process that regulated the size of the Ag NWs was developed by varying the types of control agents. Three as-synthesized Ag NW 1–3 samples have been produced under 140 °C utilizing NaCl, CuCl2 and FeCl3 as control agents, providing us with novel synthesized methods in designing and synthesizing Ag NWs of diverse sizes. Three as-synthesized Ag NW 1–3 samples have been systemically characterized through scanning electron microscopy and powder X-ray diffraction. The application values of the samples on cardioplegia after anesthesia combined with a synergistic leukocyte filter were analyzed, and the associated mechanism was studied. The superoxide dismutase activation in cardiomyocytes was investigated employing real time RT-PCR. The serum lactate dehydrogenase and serum malondialdehyde levels were then determined using ELISA.

Regulation of the Diameter and Length of Silver Nanowires and Their Therapeutic Effect on Postmenopausal Osteoporosis

Postmenopausal osteoporosis is a systemic bone metabolic disease occurring in postmenopausal women. In this research, silver nanowires (Ag NWs) with different sizes were synthesized via poly-process synthesis by using different control agents and then characterized by scanning electron microscopy and powder X-ray diffraction. Their application values in postmenopausal osteoporosis were evaluated, and the related mechanism was explored.

High-temperature resistance of flexible transparent conductive films based on Ag@SnO2 core-shell nanowires for 300 °C

• Ag NWs are encapsulated uniformly in thin SnO 2 shells via solution grown method. • FTCF possess high transmittance of 85.3% and low sheet resistance of 9.3 Ω/sq. • EDS mapping results show that SnO 2 shell is formed on surface of Ag NW. • FTCFs are robust and able to withstand high temperature of 300 ℃. High-temperature resistance of flexible transparent conductive film (FTCF), consisting of an Ag@SnO 2 core−shell nanowire (Ag NW@SnO 2 ) network embedded in a colorless polyimide (cPI), is fabricated by all-solution-process. The Ag NW@SnO 2 are synthesized via a redox reaction in the presence of water. The energy-dispersive X-ray spectroscopy mapping results demonstrate that a SnO 2 thin-shell is coated uniformly on the surface of Ag NW. The obtained FTCF shows low sheet resistance of 9.3 Ω/sq. with ∼85.3% of optical transmittance. Imbedding the Ag NW@SnO 2 network into cPI film enhances the thermostability and improves the mechanical flexibility of the FTCF. Particularly, the FTCFs can withstand a high temperature of 300 ℃ in air without deterioration of conductivity. The robust high-temperature FTCFs in this study hold promising commercial application in flexible and high temperature occasions.

Ag Nanostructure Morphologies and Physicochemical Properties Dictated by the Polyols Used in the Synthesis

: The mixing of ethylene glycol (EG) with diethylene glycol (DEG) has been studied to analyse the effect of viscosity rise of solvent on the Ag nanostructures and their morphologies. The rise of viscosity has been adjusted by increasing the molar ratio of DEG to EG under optimized conditions of temperature and capping agent- polyvinylpyrrolidone (PVP). It has been seen that increasing the proportion of DEG resulted increasing the viscosity of solution and thus decreased the diameter of nanowires. The production of quantum nanowires has further become possible during reaction. The synthesized material was characterized using UV−Vis spectroscopy, SEM, EDX, XRD, PL and DSC. Surface Plasmon resonance and luminescence was determined using UV−Vis spectroscopy and PL spectroscopy. The data showed that Ag nanowires have a strong absorption band at 356 nm and 401 nm which can be attributed to the transverse and longitudinal surface Plasmon resonance. The XRD results indicated that the prepared product is made of pure Ag with face centred cubic structure, and the DSC analysis demonstrated the presence of amorphous domain within metal nanostructures. Finally, temperature fluctuations have caused the formation of nanoparticle of different shapes and sizes which bears the synthetic mechanistic insights. Our research work supplies new evidence to illustrate the actual growth mechanism and kinetics of silver nanowires. The main objective of this study is to investigate the effect of solvent in polyol synthesis of silver nanowires (Ag NWs) on the nanostructures diameter and morphologies

Preparation of Low Volatile Organic Compounds Silver Paste Containing Ternary Conductive Fillers and Optimization of Their Performances.

Conductive silver paste is a key material in the fields of printed circuits and printed electronic devices. However, the preparation of conductive silver paste with low-cost and volatile organic compounds (VOCs) is still a challenge. In this work, conductive silver pastes with excellent comprehensive performances were developed by using water-borne polyurethane (WPU) as the bonding phase and using the ternary mixture of Ag microflakes (Ag MFs), Ag nanowires (Ag NWs), and Ag nanoparticles (Ag NPs) as the conductive phase. WPU endowed conductive silver pastes with the adhesion along with releasing a few VOCs during the curing. Results showed that a small amount of Ag NPs or Ag NWs dramatically enhanced the electrical conductivity of silver paste paint film filled only with Ag MFs. The electrical resistivity for optimal ternary mixture conductive silver paste was 0.2 × 10-3 Ω∙cm, and the conductive phase was composed of 20.0 wt% Ag MFs, 7.5 wt% Ag NWs, and 2.5 wt% Ag NPs. Meanwhile, the adhesive strength and hardness of silver paste paint film were effectively improved by increasing the curing temperature. The optimal overall performance of the conductive silver pastes was achieved at the curing temperature of 160 °C. Therefore, this work can provide a new route for preparing conductive silver pastes with high performances.

A platinum modulated tungsten oxide on Ag nanowires network as an indicator for in-situ visualized evaluation of the hydrogen evolution performance

The development of the real-time evaluation for the catalytic hydrogen evolution performance under a simple and convinient condiction is urgently needed, but still a great challenge. Herein, a platinum modulated WOx on Ag nanowires (Pt-WOx@Ag NWs) is developed as an optical-electrochemical catalyst to realize an in-situ intuitive evaluation for the hydrogen evolution performance, in which the color of as-prepared Pt-WOx@Ag NWs catalyst changes from the transparent to the deep blue with the increase of the applied potential. The real-time H2 evolution with an H2 turnover frequency (from 0 to 2.26 s−1 per site), optical transmittance (from 80.3% to 48.7% at the wavelength of 630 nm) and energy consumption (from 0 to 0.74 W h in 1 h) is established. The charge transfer and mass transport are greatly promoted by the three demensional Ag NWs conductive network and abundant active sites, which are provided by the platinum modulated WO3 on the Ag substrate. Density functional theory (DFT) calculations indicate that the modified WOx shows the preferred adsorption affinity toward H2O (ΔGH2O, −0.17 eV), which reach a high coloration efficiency and optical modulation range for the electrochromic reaction. The Pt sites on WOx with a suitable H binding energy (ΔGH∗, 0.38 eV) efficiently promote the H∗ conversion and H2 release of water splitting. This work propose an intelligent hydrogen evolution indicator by real-time color change to boost the high-quality development of green hydrogen energy.

All Digital Light Processing‐3D Printing of Flexible Sensor

AbstractFlexible sensor with high sensitivity, high durability, and facile fabrication process has promising applications in structural health monitoring, human–machine interface, and soft robotics areas. Digital light processing‐3D (DLP‐3D) printing can print flexible sensor in a scalable process. However, to achieve all DLP‐3D printing of flexible sensor, there still exist challenges of how to print sensing units with high sensitivity to external stimuli, interconnectors with high conductive stability at deformations, and robust interfaces between them for long‐term usage. To address this, a hybrid DLP‐3D printing method is developed, including the key steps of printing carbon nanotube/elastomer (MWCNT/EA) as sensing units and selective electrostatic self‐assembly of silver nanowires (Ag NWs) as interconnectors. As a demonstration, a flexible pressure sensor array integrated with amplifier circuit is fabricated by the method. The MWCNT/EA sensing unit with woodpile structure has nine times improved sensitivity than the solid one. The Ag NW interconnector with serpentine configuration shows insensitivity to strain and good mechanical stability. The interface between sensing unit and interconnector is mechanical robust due to the chemical bond formation under ultraviolet radiation. The flexible sensor could detect external stimuli with enhanced signals enabled by integrated amplifier circuit, exhibiting potentials of the method for flexible electronic fabrication.

Encapsulation of locally welded silver nanowire with water-free ALD-SbOx for flexible thin-film transistors

Transparent conductive electrodes are essential in the application of flexible electronics. In this work, we successfully demonstrated a novel strategy for improving mechanical/electrical properties of indium tin oxide (ITO)-free flexible silver nanowire (Ag NW) thin films. To reduce the contact resistance of Ag NWs, an ethanol-mist was used to weld the cross junction of wires at room temperature. The nano-welded Ag NWs (W-Ag NWs) were then coated with an aluminum-doped ZnO (AZO) solution, which significantly reduce the roughness of the Ag NW thin film. Finally, an ultrathin SbOx thin film of 2 nm was deposited on the film surface using a water-free low-temperature atomic layer deposition technique to protect the W-Ag NW/AZO layer from water or oxygen degradation. The treated Ag NWs have a high transmittance of 87% and a low sheet resistance of about 15 Ω/sq, which is comparable with the ITO electrode's property. After 1000 cycles of bending testing, the W-Ag NW/AZO/SbOx film practically retains its initial conductivity. Furthermore, the samples were immersed in a solution with pH values ranging from 3 to 13 for 5 min. When compared to untreated Ag NWs or those coated with AlOx thin films, W-Ag NW/AZO/SbOx had superior electrical stability. The W-Ag NW/AZO/SbOxlayer was integrated as a gate electrode on low-power operating flexible Ti-ZnO thin film transistors (TFTs). The 5% Ti-ZnO TFT has a field-effect mobility of 19.7 cm2 V s−1, an Ion/Ioff ratio of 107, and a subthreshold swing of 147 mV decade−1.

Regulating Monolayer Aligned Silver Nanowire Coatings for Energy-Saving Windows

Low-emissivity (low-e) glass has garnered considerable attention for implementation in energy-saving windows, which can effectively decrease the energy consumption of buildings. However, the traditional vacuum-coating technology of low-e films greatly enhances the cost of energy-saving windows, and the influence of the vacuum-coating parameters on the optical characteristics of low-e films necessitates a complex optimization process. Herein, we prepared Ag NWs with controllable diameters using the polyol method, and the alignment of the Ag NW film coating on glass substrates was regulated by the shear force of the liquid flow generated through magnetic stirring. After optimization, the low-εMIR windows based on aligned Ag NW (60 nm) coatings showed an optical transmittance of 84.4% and a low εMIR of 0.3, which were superior to those of commercial low-εMIR glass (T: 65.6%; εMIR: 0.4). The simplicity and low cost of aligned Ag NW coatings for low-e glass open up a new avenue for reducing energy consumption in existing windows.