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

Recent Advances in Transparent Electrodes and Their Multimodal Sensing Applications

This review examines the recent advancements in transparent electrodes and their crucial role in multimodal sensing technologies. Transparent electrodes, notable for their optical transparency and electrical conductivity, are revolutionizing sensors by enabling the simultaneous detection of diverse physical, chemical, and biological signals. Materials like graphene, carbon nanotubes, and conductive polymers, which offer a balance between optical transparency, electrical conductivity, and mechanical flexibility, are at the forefront of this development. These electrodes are integral in various applications, from healthcare to solar cell technologies, enhancing sensor performance in complex environments. The paper addresses challenges in applying these electrodes, such as the need for mechanical flexibility, high optoelectronic performance, and biocompatibility. It explores new materials and innovative techniques to overcome these hurdles, aiming to broaden the capabilities of multimodal sensing devices. The review provides a comparative analysis of different transparent electrode materials, discussing their applications and the ongoing development of novel electrode systems for multimodal sensing. This exploration offers insights into future advancements in transparent electrodes, highlighting their transformative potential in bioelectronics and multimodal sensing technologies.

Versatile Applications of Silver Nanowire-Based Electrodes and Their Impacts

Indium tin oxide (ITO) is currently the most widely used material for transparent electrodes; however, it has several drawbacks, including high cost, brittleness, and environmental concerns. Silver nanowires (AgNWs) are promising alternatives to ITO as materials for transparent electrodes owing to their high electrical conductivity, transparency in the visible range of wavelengths, and flexibility. AgNWs are effective for various electronic device applications, such as touch panels, biosensors, and solar cells. However, the high synthesis cost of AgNWs and their poor stability to external chemical and mechanical damages are significant challenges that need to be addressed. In this review paper, we discuss the current state of research on AgNW transparent electrodes, including their synthesis, properties, and potential applications.

Solution processed high performance perovskite solar cells based on a silver nanowire-titanium dioxide hybrid top electrode

Longer silver nanowires (AgNWs) > 50 μm and even 90 μm in length have been produced via a polyol method by just changing the stirring speed at a temperature of 130 °C. As-synthesized longer AgNWs are further utilized to construct transparent conductive AgNWs films by a facile drop-casting technique that attained a sheet resistance of 14.5 Ω sq-1 and transmittance over 85%, which is higher than ITO film. The use of a AgNWs/TiO2 hybrid electrode decreases the sheet resistance to 8.3 Ω sq-1, which is attributed to the enhancement of connections between AgNWs by filling the empty spaces between nanowires and TiO2 nanoparticles. Transparent perovskite solar cells (PSCs) on the basis of these AgNWs and AgNWs/TiO2 hybrid top electrodes were made and examined. Due to the light scattering nature of TiO2 nanoparticles, optical transmittance of the AgNWs/TiO2 hybrid electrode enhances to some extent after the coating of a TiO2 layer. Both cell efficiencies and stability of the PSCs are enhanced by using the AgNWs/TiO2 top electrode. A power conversion efficiency (PCE) of 10.65% was attained for perovskite devices based on only the AgNW electrode with a sheet resistance of 14.5 Ω sq-1. A PCE of 14.53% was achieved after coating with TiO2 nanoparticles, indicating the layer effect of TiO2 coating.

Soft Material-Enabled Electronics for Medicine, Healthcare, and Human-Machine Interfaces

Soft material-enabled electronics offer distinct advantages over conventional rigid and bulky devices for numerous wearable and implantable applications. Soft materials allow for seamless integration with skin and tissues due to the enhanced mechanical flexibility and stretchability. Wearable devices with multiple sensors offer continuous, real-time monitoring of biosignals and movements, which can be applied for rehabilitation and diagnostics, among other applications. Soft implantable electronics offer similar functionalities, but with improved compatibility with human tissues. Biodegradable soft implantable electronics are also being developed for transient monitoring, such as in the weeks following surgeries. New composite materials, integration strategies, and fabrication techniques are being developed to further advance soft electronics. This paper reviews recent progresses in these areas towards the development of soft material-enabled electronics for medicine, healthcare, and human-machine interfaces.

Synthesis and Applications of Silver Nanowires for Transparent Conductive Films

Flexible transparent conductive electrodes (TCEs) are widely applied in flexible electronic devices. Among these electrodes, silver (Ag) nanowires (NWs) have gained considerable interests due to their excellent electrical and optical performances. Ag NWs with a one-dimensional nanostructure have unique characteristics from those of bulk Ag. In past 10 years, researchers have proposed various synthesis methods of Ag NWs, such as ultraviolet irradiation, template method, polyol method, etc. These methods are discussed and summarized in this review, and we conclude that the advantages of the polyol method are the most obvious. This review also provides a more comprehensive description of the polyol method for the synthesis of Ag NWs, and the synthetic factors including AgNO3 concentration, addition of other metal salts and polyvinyl pyrrolidone are thoroughly elaborated. Furthermore, several problems in the fabrication of Ag NWs-based TCEs and related devices are reviewed. The prospects for applications of Ag NWs-based TCE in solar cells, electroluminescence, electrochromic devices, flexible energy storage equipment, thin-film heaters and stretchable devices are discussed and summarized in detail.

Enhancing Thermal Oxidation Stability of Silver Nanowire Transparent Electrodes by Using a Cesium Carbonate-Incorporated Overcoating Layer

Despite their excellent electrical and optical properties, Ag nanowires (NWs) suffer from oxidation when exposed to air for several days. In this study, we synthesized a Cs carbonate-incorporated overcoating layer by spin-coating and ultraviolet curing to prevent the thermal oxidation of Ag NWs. Cs incorporation increased the decomposition temperature of the overcoating layer, thus enhancing its thermal resistance. The effects of the Cs carbonate-incorporated overcoating layer on the optoelectrical properties and stability of Ag NWs were investigated in detail. The Ag NW electrode reinforced with the Cs carbonate-incorporated overcoating layer exhibited excellent thermal oxidation stability after exposure to air for 55 days at 85 °C and a relative humidity of 85%. The novel overcoating layer synthesized in this study is a promising passivation layer for Ag NWs against thermal oxidation under ambient conditions. This overcoating layer can be applied in large-area optoelectronic devices based on Ag NW electrodes.

Improvement of Electro-Optical Properties of PSLC Devices by Silver Nanowire Doping

Polymer stabilized liquid crystal (PSLC) devices modulating the light that goes through them have broad applications. In this study, to improve the electro-optical properties of a PSLC device, Ag nanowires with diameter about 20 nm were doped into PSLC active layer with different concentrations. The influence of Ag nanowires concentration on the driving voltage, on-state response time and frequency modulation characteristics of a PSLC device were studied. The results indicate that the doping of Ag nanowires can reduce the driving voltage of PSLC cell up to 42%. The response time of the PSLC cell can decrease by about 41%. Meanwhile, frequency modulation does not show significant improvement upon Ag nanowire doping. Overall, Ag nanowire doping can improve the electro-optical properties of PSLC device effectively.