Metal Nanowire based Transparent Electrodes
Metal nanowire films are increasingly used as transparent electrodes in many applications, including touch screens, displays, smart windows, EMI shielding and others.
The group of Prof. Gil Markovich from Tel Aviv University developed a unique process for growing patterned conductive transparent silver nanowires thin film electrodes. In this unique process the nanowires grow in-situ, directly on the substrate, enabling easy patterning of the films during the coating process. In contrast, other methods of producing silver nanowire films deposit pre-grown nanowires on the surface and then treat them at elevated temperature so they merge into a uniform network.
The developed process includes three steps:
Substrate seeding with gold nanoparticles, which may be performed using printing of patterned structures
Nanowire growth from seeds by applying a growth solution on the substrate
Nanowire metallization directly on the substrate, using silver plating solution
When required by the application, additional protective layer can be deposited on top of the silver nanowire layer.
The process is water based, performed close to room temperature, and is environmentally friendly.
The growth can be performed on various substrates, including glass and PET (both flat and curved). Patterning is easily performed during the seeding step using inkjet (line widths down to 20 μm) or photolithography (for narrower lines). Typical coating cost (per unit area) is comparable to that of ITO, and is likely to be lower if patterning is required.
The resulting coating demonstrates high transparency (87-95%) and low haze (<1-2%) for sheet resistances in the range of 20 – 350 /□. The protected films have good adhesion to the substrate and withstand extreme conditions (65oC/95% humidity, -40oC).
Sample films coated on desired glass or plastic substrates of up to 10X10 cm2 can be produced with/without patterning and with/without protective polymer layer for evaluation