Conductive materials for printed electronics were one of the interesting topics on the morning of the second day of the IDTechEx conference Printed Electronics Europe 2009 in Dresden, Germany. Applied Nanotech, Vorbeck Materials and others presented about their recent findings in this fundamental field. Read more about the most interesting ones:
Dr Zvi Yaniv from Applied Nanotech presented a novel inkjettable copper ink that only needs a drying temperature of >100°C and no inert atmosphere for the photosintering process. The ink based on copper nanoclusers (Cu NC) was already tested with a piezo-inkjet printer from Dimatix. In collaboration with Optomec an aerosol inkjet printer was also tested using Kapton®, a polymide material from DuPont, and glass as subtrate. Repeatable copper traces achieved a resistivity of 3 x 10-6 - 4 x 10-6 ohm/cm. These initial results show that RF attenuation is comparable if not better that traces using Ag ink. Applied Nanotech secured production of copper nanoparticles, in quantities of hundreds of kilograms per month, suitable for the ink production.
Optomec aerosol inkjet printing process. Courtesy of Applied Nanotech.
Vorbeck Materials supplying several types of Graphene ink enables the use of this extraordinary material for printed electronics. Graphene are single-atom thick sheets of carbon with exceptional strength and stability along with unique electrical and thermal properties. Dr. John S. Lettow, President, delivered a highly interesting talk about the several conductive Vor-Inks available in ton scale for screen, gravure and spray printing. The eco-friendly formulations show repeatable quality, high conductivity, excellent flexibility and form robust films, that don't need to be sintered, on a wide range of substrates. Performance: 1 Ω/sq resistivity @ 1 mil, ~ 300 S/cm @ 1-5 µm, abrasion resistance: 2-3H, rub resistance: 5-8% loss after 10 rubs, flex resistance: 13-15% loss after 100 flexes. These conductive materials can potentially be used for flexible backplanes for displays and photovoltaic's as well as for UHF and capacitive RFID.
Courtesy of Vorbeck Materials.
Frank Louwert from Agfa-Gevaert presented the newest developments in Pedot technology. Orgacon™ GEN 4 shows a 3.5x lower surface resistance in comparison to the first generation of their Pedot material as well as an improved light stability. These are two of the key properties next to high conductivity and excellent transparency that are necessary for the use in large area applications like OLED lighting and Photovoltaics. Together with Kabay the new high bright AC-EL was developed (223cd/qm @ 125V and 400Hz), where Orgacon benefits to the "reversed" built up; transparent conducting layer needs to be printed over the ZnS layer. The goal for the near future remains to improve the characteristics of Orgacon so that it can be used as an ITO alternative for transparent OLED electrodes. As a first step an ITO- and litho-free OLED on foil was recently developed in collaboration with Holst Centre.
12x12cm ITO - and litho-free OLED on PEN with Orgacon G4 as transparent electrode. (Courtesy of Agfa-Gevaert).