Ag Nanowire Films Research Articles

Magnetic flexible sensor with randomly distributed pine-branch microstructure for bidirectional recognition

Flexible sensors have been widely used in smart wearable devices, in which the multifunctional selectivity and mechanical property receive the main attention. However, a simple process for preparing sensors which can recognize different forms of mechanical stimuli is still a challenge. This paper reports a magnetic thin-film sensor (MP-Ag-MP) consisting of magnetic PDMS matrix and conductive Ag nanowires film with pine-branch microstructure by using sandpaper as an abrasive template. Due to its upper and lower asymmetric microstructures, the sensor has diametrically opposed electrical signal responses to bending stimuli in different directions, thus enabling the differentiated monitoring of in-plane and out-plane bending, and the sensitivities can respectively reach −9.04 × 10−2/mm and 12.87 × 10−2/mm in the sensing range. Moreover, it can also respond promptly to different magnetic field directions and intensities, which demonstrates excellent magnetic sensing performance. The sensor can be applied to monitor various human joint motions and construct a Morse code encryption-decryption system. Furthermore, a stress-magnetic bi-functional control system integrated with Bluetooth transmission function can be designed to wirelessly control the motion of the smart cart. As a result, this randomly distributed pine-branch microstructure endows the wonderful bi-directional sensing function and provides high potential application in smart wearable devices.

(Invited) Vertical Transparent ZnO TFT Based on a Stack of Thin-Films Deposited in Solution

A lot of works are devoted now to integrate driving TFT with OLED, minimizing the area of the pixel. In other part, people try to fabricate devices using low cost technologies as deposition in solution avoiding any photolithography step in the process. Finally, it can be better if the full driving TFT-OLED device is transparent.The present work try to answer simultaneously to these 3 desires. Particularly, the present paper focus on the TFT.Vertical TFT will answer to the first desire to minimize the area of the device. It is based here on a stack of the gate, the insulator, the source, the semiconducting active layer and the drain; meaning 5 films all solution deposited.Thanks to the present available insulator solutions for the deposition, different insulators can be chosen. High k HFO2 insulator is chosen in this work. It is is spincoated and then annealed at 300C during 1 hour. Figure 1 shows the current-voltage curves of ITO/HFO2/AgNWs stack. After rapid increase, the current stabilizes at 10 pAmp at least still a voltage of 10V, meaning a field of 7.7x105 V/cm2 with a thickness of 130 nm. Present HFO2 film is then a good insulator.ZnO is chosen as active layer. It is spin-coated and then annealed at 180C. This temperature was found enough high to lower the conductivity (Figure 2)The source and drain layers are spin-coated using Ag nanowires (AgNWs) solution. As source AgNWs layer is deposited before ZnO layer, it will be annealed at the same temperature 180C. Figure 3 shows that AgNWs film stays enough conducting after such annealing temperature. It can be used as conducting source and drain.Finally, the full stack of 5 films is characterized as a TFT.Figure 4 shows the transfer characteristic of this TFT plotted at a drain voltage of 2.6V. The drain current is modulated by 4 orders from off to on regime.Very simple and low cost fully in solution process is presented in this work. Working transparent TFT is demonstrated. The process shows its high potential in the development of integrated TFT-OLED in small area. It is very promising.Its shows also the need of future hard work in this way to demonstrate fully integrated driving TFT-OLED Figure 1

UV–Vis Transparent Conductive Film Based on Cross-Linked Ag Nanowire Network: A Design for Photoelectrochemical Device

The FTO/ITO transparent conductive films currently used in photoelectrochemical devices limit performance improvement due to their low conductivity, poor flexibility, and inability to transmit UV light. Ag nanowire-based films are a very promising alternative to address these problems, and are considered to be the next generation in transparent conductive film. Here, we prepared a cross-linked nano-network composed of ultra-long Ag nanowires by a special physical template method. The obtained Ag nanowire transparent conductive film has a transmittance of over 80% in a wide range of 200 nm–900 nm, a sheet resistance as small as 5.2 Ω/sq, and can be easily transferred to various substrates without damage. These results have obvious advantages over Ag nanowire films obtained by traditional chemical methods. Considering the special requirements of photoelectrochemical devices, we have multifunctionally enhanced the film by a TiO2 layer. The heat-resistant temperature of transparent conductive film was increased from 375 °C to 485 °C, and the mechanical stability was also significantly improved. The presence of the multifunctional layer is expected to suppress the carrier recombination in self-powered photoelectrochemical devices and improve the electron diffusion in the longitudinal direction of the electrode, while serving as a seed layer to grow active materials. The high-quality Ag nanowire network and functional layer synergize to obtain a UV–Visible transparent conductive film with good light transmittance, conductivity, and stability. We believe that it can play an important role in improving the performance of photoelectrochemical devices, especially the UV devices.

Iodine ion modification enables Ag nanowire film with improved carrier transport properties and stability as high-performance transparent conductor

Iodine ion modification enables Ag nanowire film with improved carrier transport properties and stability as high-performance transparent conductor

Self-Powered Flexible Electrochromic Smart Window.

Electrochromic devices have attracted considerable interest for smart windows. However, current development suffers from the requirement of the external power sources and rigid ITO substrate, which not only causes additional energy consumption but also limits their applications in flexible devices. Inspired by galvanic cell, we demonstrate a self-powered flexible electrochromic device by integrating Ag/W18O49 nanowire film with the Al sheet. The Ag nanowire film first acted as the electrode to replace the ITO substrate, then coupled with the Al sheet to induce an open-circuit voltage of ∼0.83 V, which is high enough to drive the coloration of W18O49 nanowires. Remarkably, the flexible self-powered electrochromic device only expends ∼6.8 mg/cm2 of the Al sheet after 450 electrochromic switching cycles and the size can be easily expanded with an area of 20 × 20 cm2, offering significant potential applications for the next generation of flexible electrochromic smart window.

A multi-responsive healable supercapacitor

Self-healability is essential for supercapacitors to improve their reliability and lifespan when powering the electronics. However, the lack of a universal healing mechanism leads to low capacitive performance and unsatisfactory intelligence. Here, we demonstrate a multi-responsive healable supercapacitor with integrated configuration assembled from magnetic Fe3O4@Au/polyacrylamide (MFP) hydrogel-based electrodes and electrolyte and Ag nanowire films as current collectors. Beside a high mechanical strength, MFP hydrogel exhibits fast optical and magnetic healing properties arising from distinct photothermal and magneto-thermal triggered interfacial reconstructions. By growing electroactive polypyrrole nanoparticles into MFP framework as electrodes, the assembled supercapacitor exhibits triply-responsive healing performance under optical, electrical and magnetic stimuli. Notably, the device delivers a highest areal capacitance of 1264 mF cm−2 among the reported healable supercapacitors and restores ~ 90% of initial capacitances over ten healing cycles. These prominent performance advantages along with the facile device-assembly method make this emerging supercapacitor highly potential in the next-generation electronics.

A simple and effective method via PH1000 modified Ag-Nanowires electrode enable efficient flexible nonfullerene organic solar cells

Flexible transparent electrodes (FTEs) play an important role in determining the performance of flexible organic solar cells (OSCs), Ag-nanowires (AgNWs) with the unique merits of high conductivity, excellent flexibility, and good thermal stability has been taken into more consideration in fabricating highly efficient FTEs. However, the pristine AgNWs film usually suffers a huge surface roughness and incompatibility with the organic absorption layer, thus always leads to a poor power conversion efficiency (PCE). Herein, we demonstrated a simple and effective way through employing poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PH1000) to modify the surface of AgNWs to prepare high-quality FTEs. Based on the PH1000 (100 nm)/AgNWs FTEs, the optimized flexible OSC with PM6:Y6 as active layer exhibits a highest PCE of 12.71%, with an open-circuit voltage ( V oc ) of 0.814 V, a short-circuit current ( J sc ) of 22.61 mA/cm 2 , and a fill factor ( FF ) of 0.691, respectively. Which is much higher than the PCE (7.20%) of pristine AgNWs FTEs based device. The enhanced device performance was attributed to the improved morphologies both of the FTEs and the active layers, more effective charge transport and collection efficiency, as well as the decreased charge recombination properties. This work provides an efficient way to fabricate high-quality FTEs and realize efficient flexible OSCs. The significant improvement on the performance of flexible organic solar cells is achieved by employing PH1000 to modify AgNWs transparent electrodes. This work provides a simple and effective way to realize efficient flexible OSCs. • PH1000/AgNWs flexible transparent electrodes (FTEs) was prepared. • A highest PCE of 12.71% of flexible OSCs was realized. • This work provides an efficient way to fabricate high-quality FTEs and realize efficient flexible OSCs.

Polymer Ligand Design and Surface Modification of Ag Nanowires toward Color-Tone-Tunable Transparent Conductive Films

Ag nanowire suspensions are one of the indispensable materials in the design and fabrication of flexible transparent conductive films. Although the required properties of Ag nanowire films, such as their high transparency, low haze, low contact resistance, and suppression of yellowing, are strongly related to the nanowire surface phenomena, approaches for the surface modification of polyol-synthesized Ag nanowires have rarely been reported. Here, we report the design of a polymer ligand and surface modification of Ag nanowires with the designed polymer to obtain color-tunable transparent conductive films through a simple casting and drying process. In this approach, we synthesized a series of functional polymer ligands by partially grafting polyethyleneimine (PEI) with polyethylene glycol (PEG) chains (PEI-mPEG). The amine sites in PEI-mPEG were designed to act as adsorption sites as well as anchoring sites for an anionic blue dye for suppressing the yellow color tone of Ag nanowires. On the other hand, the PEG chains were designed to maintain the stability of the Ag nanowires in aqueous suspensions and to suppress corrosion of Ag nanowires, which is enhanced by the amine groups of PEI. The effect of the grafting ratio of PEG chains on PEI on the ligand-exchange behavior of the Ag nanowires, their dispersion stability in aqueous inks, and final film properties were investigated systematically. Furthermore, successful color tuning of the Ag nanowire film, without suppressing the conductive and optical properties, is demonstrated by loading anionic blue dye onto PEI-mPEG-modified Ag nanowires.

Silver Nanowire Networks: Silver Nanowires Network Film with Enhanced Crystallinity toward Mechano‐Electrically Sustainable Flexible‐Electrode (Adv. Mater. Technol. 1/2021)

In article number 2000838, Mi-Jeong Kim, Hiesang Sohn, and co-workers present crystallized Ag nanowires film (c-Ag NWs), prepared through solution annealing (70 °C) for flexible electronic devices. The c-Ag NWs film shows excellent mechano-electric stability (resistance change, ΔR/ΔRo: 45%) after 200 000 bending cycles under strain of 6.7%. Additionally, c-Ag NWs based patterned electrode demonstrates the comparable electrical property (9.41 kΩ) to that of ITO-based one (8.01 kΩ).

Surface enhanced Raman studies of heat-treated silver nanowire films

Abstract We report the surface enhanced Raman activity of heat treated silver [Ag] nanowires [NWs] in Isopropyl Alchol [IPA][Sigma Aldrich] with ∼30 picosecond laser pulses. Surface enhance Raman scattering study was carried out for MB molecules at concentrations of 5 µM, 500 nM, 50 nM using an excitation wavelength of 785 nm. Ag NWs in IPA were heat treated (30 mins) with ∼30 ps pulses at energies ∼5 mJ, ∼10 mJ, ∼15 mJ, and ∼20 mJ at a wavelength ∼532 nm and the films were prepared from heat treated Ag NWs. Raman activity of these films before and after heat treatment was compared for the elevated Raman mode, corresponding to 1622 cm-1of Mythelene Blue. It was observed that the Mythelene Blue at 5 µM concentration demonstrated higher enhancement factor(∼106) for 1622 cm−1 mode from heat treated Ag nanowire films than untreated (∼104) and the other concentrations demonstrated the same trend.

Effect of AlOx protection layer on AgNWs for flexible transparent heater

We indicated high performance and stability transparent heaters based on AlOx covered Ag nanowires. We obtained an AlOx covered Ag nanowire thin film which has a 47 ohm/sq of sheet resistance and 88.1% (substrate included) of transmittance at 600 nm on a flexible substrate. We demonstrate that the thin AlOx layer leads to increased contact area at the junction of Ag nanowires, which contributes to lower sheet resistance and improved adhesion of Ag nanowires. Furthermore, high stability and flexibility of Ag nanowire have been achieved by the AlOx layer. Finally, we fabricated a flexible transparent heater with AlOx covered Ag nanowire, and obtained a temperature of 81 °C within 40 sec at the driven voltage of 7 V with fast response and uniform temperature distribution. Therefore, the AlOx covered Ag nanowire film is a promising candidate for the application of the flexible transparent heaters.

A solution processed Ag-nanowires/C60 composite top electrode for efficient and translucent perovskite solar cells

All solution-processed semi-transparent perovskite solar cells (PSCs) with high efficiency were fabricated with Ag nanowire (AgNW) top electrode directly coated on the organic electron transport layer (ETL). A unique AgNW/ETL interface morphology was attained by the fabrication of the AgNW-C60 composite electrode through a sequential spin-coating method. The C60 filler spin-coated on the AgNW network engendered a high contact area and favourable energy level alignment at the interface between the ETL and AgNW. As a result, devices based on AgNW-C60 electrode far outperformed devices with pristine AgNW electrodes. By adjusting the thickness of the AgNW film, the AgNW-C60 devices attained a PCE of 11.02%. The incorporation of C60 into the AgNW electrode also led to remarkable stability improvement. The low-temperature solution-processed and semi-transparent AgNW-C60 top electrode is also applicable to other PSC structures with various interfacial layers, thus showing a promising path towards fully-printable, flexible and translucent photovoltaic devices.

AgNWs/AZO composite electrode for transparent inverted ZnCdSeS/ZnS quantum dot light-emitting diodes

Fully transparent inverted quantum dot light-emitting diodes (QLEDs) were fabricated by incorporating a Ag-nanowire-based anode. Aluminum-doped zinc oxide (ZnO:Al, AZO) was inserted by atomic layer deposition and reduced the sheet resistance by promoting adhesion of Ag nanowires (AgNWs) film and increasing its chemical stability towards oxygen. The performance of the QLEDs was optimal when the thickness of AZO was 20 nm. The current efficiency of the fully transparent inverted QLEDs integrated with the AgNWs/AZO anode reached 15.33 cd A−1. The main peak wavelength and optical transmittance of the inverted QLEDs were 530 nm and 75.66%, respectively. This discovery is expected to provide a basic method for the production of flexible displays with full transparency by AgNWs-based electrodes.

Highly accurate particulate matter detection assisted by an air heater based on a silver nanowire film

Recently, many studies have been carried out to solve the particulate matter pollution problem. However, the detection accuracy for particulate matter in the atmosphere remains unsatisfactory due to the influence of the air relative humidity. Herein, we report a Ag nanowire film air heater to enhance the detection accuracy through internal heating. From air temperature and air relative humidity relationship analysis, it has been found that the Ag nanowire film air heater can form the most suitable air relative humidity in the detection system, thereby enhancing the detection accuracy. Consequently, the Ag nanowire film air heater-assisted light scattering particulate matter detector has achieved tremendous enhancement in its detection accuracy, which is comparable with the data obtained by the beta gauge method. Film resistance plays a key role in internal air temperature distribution and the resultant air relative humidity at given voltages. To achieve the most suitable air relative humidity for continuous online monitoring, response time and power consumption should be balanced. Therefore, guidance for designing Ag nanowire films with proper resistance used in an optional-sized detector has been given for quick response, high accuracy and low power consumption. This work is of significance for providing insight for future studies in particulate matter detection and pollution remediation.

Fabrication, Mechanisms, and Properties of High-Performance Flexible Transparent Conductive Gas-Barrier Films Based on Ag Nanowires and Atomic Layer Deposition.

Thin films of Ag nanowires (NWs) offer many advantages as transparent electrodes for flexible electronics, but their applications are hindered by issues including poor stability/durability of Ag NWs, high processing temperatures, heterogeneity of surfaces, and lack of gas-barrier function. This study reports novel mechanisms through which a conductive Hf:ZnO (HZO) film by atomic layer deposition (ALD) can be integrated with a sprayed Ag NWs film to address the issues of Ag NWs. First, the ALD surface reactions can induce fusing of the Ag NWs into a connected network without the need for a thermal sintering process. Second, the ALD process can in situ functionalize the Ag NWs to yield defect-free (in terms of blocking gas permeation) coverage of the ALD HZO over the entire nanowire surfaces, which also enhances the ALD-induced fusing of Ag NWs. The composite HZO/Ag NWs films exhibit low sheet resistance (15 Ω sq-1), low water vapor transmission rate (WVTR) (5.1 × 10-6 g m-2 day-1), high optical transmission (92%), excellent flexibility (12.5 mm bending radius), high stability/durability (against an extensive set of degradation modes and photolithographic patterning processes), and low processing temperature (90 °C) and can be used in perovskite solar cells to obtain high power conversion efficiency (14.46%).

A Highly Stretchable and Real‐Time Healable Supercapacitor

In addition to a high specific capacitance, a large stretchability and self-healing properties are also essential to improve the practicality and reliability of supercapacitors in portable and wearable electronics. However, the integration of multiple functions into one device remains challenging. Here, the construction of a highly stretchable and real-time omni-healable supercapacitor is demonstrated by sandwiching the polypyrrole-incorporated gold nanoparticle/carbon nanotube (CNT)/poly(acrylamide) (GCP@PPy) hydrogel electrodes with a CNT-free GCP (GP) hydrogel as the electrolyte and chemically soldering an Ag nanowire film to the hydrogel electrode as the current collector. The newly developed dynamic metal-thiolate (M-SR, M = Au, Ag) bond-induced integrated configuration, with an intrinsically powerful electrode and electrolyte, enables the assembled supercapacitor to deliver an areal capacitance of 885 mF cm-2 and an energy density of 123 µWh cm-2 , which are among the highest-reported values for stretchable supercapacitors. Notably, the device exhibits a superhigh stretching strain of 800%, rapid optical healing capability, and significant real-time healability during the charge-discharge process. The exceptional performance combined with the facile assembly method confirms this multifunctional device as the best performer among all the flexible supercapacitors reported to date.

Ultrasonic Modification of Ag Nanowires and Their Applications in Flexible Transparent Film Heaters and SERS Detectors.

Ultrasonic morphology modification of silver (Ag) nanowires and their applications in transparent film heaters for defogging in electric vehicles and surface-enhanced Raman scattering (SERS) detectors have been studied. With 10 min ultrasonic treatment of Ag nanowires, the electro-thermal conversion capability of Ag nanowire based transparent film heaters is efficiently improved (about 50% increase in temperature rise), which can be mainly attributed to the cross-section area reduction and the serious agglomerations of the ultrasonic modified Ag nanowire films. Furthermore, the bending or fracture caused by deformation of Ag nanowires after ultrasonic treatment provides more hot spots for SERS, and therefore lead to a significant SERS signal enhancement. This work not only greatly improves the performance of Ag nanowire based transparent film heaters and SERS detectors, but provides a new way for the functional modification of Ag nanowires.

Bendable and foldable flexible organic solar cells based on Ag nanowire films with 10.30% efficiency

Flexible organic solar cells (FOSCs) were fabricated based on Ag nanowire/PET films with PEDOT:PSS composite electrodes. The influence of doping PH1000 with ethylene glycol on the photovoltaic performance has also been investigated. Optimum FOSCs exhibit a PCE of 10.30%. All the FOSCs show excellent flexibility after bending and even upon total folding.

Facile patterning and transferring method for constructing self-powered UV photodetectors

We report a facile process for fabricating flexible self-powered UV photodetectors with a planar metal–semiconductor–metal (MSM) structure. The device was assembled by transferring ZnO nanowires (NWs) onto two electrodes consisting of Ag NWs and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/Ag NW film, both of which were formed by a simple self-assembly patterning method. The planar MSM heterostructure enables the device to generate photocurrents under zero bias voltage upon UV illumination. The smooth PEDOT:PSS/Ag NW film was found to be conducive to improving the device performance. Furthermore, the device was encapsulated in poly(dimethylsiloxane) (PDMS), ensuring a reliable performance under bending.

A Br− anion adsorbed porous Ag nanowire film: in situ electrochemical preparation and application toward efficient CO2 electroreduction to CO with high selectivity

An AgBr-derived porous Ag nanowire film with adsorbed Br− anions shows a low onset overpotential of only 296 mV and a high CO faradaic efficiency of 96.2% at −0.6 V in CO2-saturated 0.5 M KHCO3.