Takehiro Tokuno

Strongly adhesive and flexible transparent silver nanowire conductive films fabricated with a high-intensity pulsed light technique

Large-scale silver nanowire (AgNW) mesh films have received increasing attention as new transparent conductive films used in various printed devices. However, there are two crucial issues in implementing AgNWs that need to be addressed: (1) strong adhesion between AgNW film and substrate and (2) high conductivity with short treatment time for low-cost printed technology. Here, a high-intensity pulsed light (HIPL) sintering technique, which provides extreme heating locally in the AgNW film and at the interface between the film and polymer substrate, sinters the AgNW film to produce high conductivity with strong adhesion on the substrate. Importantly, light intensity, exposure time, and AgNW amount can be adjusted simply to form films that meet specific device needs. A flexible AgNW film with sheet resistance of 19 Ω sq−1 and transmittance of 83% at 550 nm is obtained with only one-step on a polyethylene terephthalate substrate with a light intensity of 1.14 J cm−2 under an exposure time of only 50 μs. The film can endure multiple peeling tests, which will play an important role in printed electronics.

Hybrid transparent electrodes of silver nanowires and carbon nanotubes: a low-temperature solution process.

Hybrid transparent electrodes with silver nanowires (AgNWs) and single-walled carbon nanotubes (SWCNTs) were fabricated on plastic films by a low-temperature solution process. The hybrid transparent electrodes exhibited a sheet resistance of 29.2 Ω/sq with a transparency of 80% when 6 wt.% of SWCNTs was mixed with AgNWs. This sheet resistance was less than one-fourth that of the AgNW transparent electrodes that were prepared using the same method. This reduction in sheet resistance is because the SWCNTs formed bridges between the AgNWs, thus, resulting in high conductivity of the hybrid transparent electrodes. The hybrid electrodes formed on plastic films exhibited high conductivity as well as excellent stability in sheet resistance when tested using a repeated bending test.PACS: 62.23.Hj; 61.48.De; 81.15.-z.

Transparent Electrodes Fabricated via the Self-Assembly of Silver Nanowires Using a Bubble Template

To shore up the demand of transparent electrodes for wide applications such as organic light emitting diodes and solar cells, transparent electrodes are required as an alternative for indium tin oxide electrodes. Herein the self-assembly method with a bubble template paves the way for cost-effective fabrication of transparent electrodes with high conductivity and transparency using self-assembly of silver nanowires (AgNWs) in a bubble template. AgNWs were first dispersed in water that was bubbled with a surfactant and a thickening agent. Furthermore, these AgNWs were assembled by lining along the bubble ridges. When the bubbles containing the AgNWs were sandwiched between two glass substrates, the bubble ridges including the AgNWs formed continuous polygonal structures. Mesh structures were formed on both glass substrates after air-drying. The mesh structures evolved into mesh transparent electrodes following heat-treatment. The AgNW mesh structure exhibited a low sheet resistance of 6.2 Ω/square with a transparency of 84% after heat treatment at 200 °C for 20 min. The performance is higher than that of transparent electrodes with random networks of AgNWs. Furthermore, the conductivity and transparency of the mesh transparent electrodes can be adjusted by changing the amount of the AgNW suspension and the space between the two glass substrates.

Properties of silver nanowire transparent electrodes fabricated by coating method

We succeeded in fabricating silver nanowire transparent electrodes on polyethyleneterephthalate (PET) films using a bending method at room temperature. The silver nanowire transparent electrodes exhibited a remarkable combination of a high electrical conductivity of 30 ohms/sq and an optical transparency of 80%. It is very interesting that sheet resistance decreased by bending of silver nanowires. This technique will be applied to the development of flexible devices such as organic solar cells, flexible displays and flexible organic light-emitting diodes.

Preparation and application rod-shaped and spherical silver nanoparticles

Silver nanoparticles with rod and round morphology have been synthesized by a simple polyol process. The morphology depended on those additives used in the process. The obtained Ag product has been applied to form a joint layer with high heat & electrical conductivity in electronic device. A transparent film and narrow conductive line with Ag nanowires have also been successfully fabricated on the glass substrates.