Technology's page: http://ramot.org/nanowires
Technology
A conductive transparent thin film which is based on gold nanowires prepared in solution and is very easy to apply to a variety of substrates using printing or spinning techniques.
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).
The Need
Currently, the existing technology for conductive transparent films uses conducting metal oxide films, primarily indium-tin oxide (ITO) and doped zinc oxide for these applications.
These films have a limited transparency/conductivity trade-off and are produced using expensive vacuum deposition techniques. They are also hard and brittle and thus not suitable for flexible coatings such as plastic electronics. Typical ITO transparency in the visible range is ~85%, while our coatings are above 90%.
Potential Applications
Applications of thin, transparent and conducting films are numerous. Currently, the most attractive application is as a transparent electrode for photovoltaic devices, although also light emitting devices require such electrodes, in particular large area displays. Our technique is very easy to implement by simple solution pouring, spinning or roll-to-roll, conforms to any type of surface and has superior transparency/conductivity tradeoff. This technology will be
very attractive to manufacturers of solar panels, touch screens, and for electromagnetic protection coatings. Our technology makes it cheaper and simpler to produce transparent conductive coatings. For power applications, such as solar panels, the improved transmission/conductivity ratio means more power can be elicited from PV panels and less unwanted heating. The resulting all-metal thin film means the coating can be extremely robust, resisting harsh environments.
Stage of Development
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.
Patents
PCT WO2010/026571 “Metal nanowire thin-films” was filed on Sept 2009. Patents granted in US, Europe, China and India
PCT WO 2013/128458 “Conductive nanowire films” was filed on Feb 2013. US 9,373,515 granted, pending in EP and China
PCT WO 2017/175215 “Printing of nanowire films” was filed April 2017
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