By David Savastano • Editor
The continued growth in key printed electronics markets, such as photovoltaics (PV), touch screens and organic light emitting diodes (OLEDs) provides opportunities for manufacturers who can develop processes that will best produce these products.
One of the areas generating great interest is energy-curing technology. Ultraviolet (UV) and electron beam (EB) curing offer many advantages, most notably instant cure, thus increasing throughput dramatically. UV and EB are also considered to be greener technologies, and can impart improved properties on products.
There still remain challenges as well, and developers are working on new capabilities for UV and EB for printed electronics.
However, the gains being made by UV and EB in photovoltaics and printed electronics in general were showcased during RadTech UV/EB Technology Conference & Expo 2010, which is concluding today at the Baltimore Convention Center.
RadTech North America, the conference’s organizers, pulled together a half-day Photovoltaics session on yesterday that drew a standing-room only audience of more than 150 attendees. More noteworthy, RadTech presented two of its prestigious Emerging Technology Awards to Cambrios and SkyFuel, Inc., two companies in the PE field that have successfully integrated UV into their manufacturing processes.
Dr. Mike Idacavage, principal research fellow, Cytec Industries, as well as RadTech North America’s president, served as the Photovoltaics session moderator. He spoke of the gains being made by UV and EB, as well as the possibilities for the future.
“Cambrios is an example of a company that is using UV successfully,” Dr. Idacavage said. “There are a lot of opportunities for energy curing, and the key is replacing existing material. There are many advantages of UV and EB including rapid processing, low heat required, the ability to modify UV and combine features.
“There are plenty of opportunities for innovative materials and processes,” Dr. Idacavage added. “We had a full house here and that indicates that suppliers and equipment manufacturers know that these opportunities exist. We tend to think that in PV that UV curing is the main opportunity, but EB also has advantages, and high throughput may make it a strong player. UV and EB are already pointed in the right direction to address these issues, whether it is for PV, OLEDs or touch screens or other potential applications.”
Cambrios received the Emerging Technology for its work on a UV curable coated nanostructured system as an alternative to ITO conductive films in flexible electronic applications.
Cambrios has developed ClearOhm silver nanostructures to replace indium tin oxide (ITO) in a wide variety of applications, including touch screens, PV and OLEDs. ITO is a highly volatile commodity, and as a ceramic, it is brittle and weakly conductive. By contrast, Cambrios’ nanostructures made from silver, a common metal, are flexible and highly conductive.
Teresa Ramos, manager materials development for Cambrios, accepted the award, and also spoke during the conference, giving her presentation on “ClearOhm Transparent Conductor: A Higher Performing, Wet Processable Alternative to Conductive Oxides.” Ramos noted that Cambrios is prepared for commercialization for touch screens this year. The company utilizes slot die coating and gravure as well as UV curing in its manufacturing process.
“It’s a very exciting time for our company. We have scaled up our process and are qualifying with lots of customers,” Ramos said. “Our ink and UV overcoat are demonstrating good coating performance. It can be patterned, and it has superior flexibility compared to ITO.” She added that Cambrios can process 50 to 100 feet of its ClearOhm nanostructures per minute.
SkyFuel, Inc., in conjunction with Red Spot Paint and Varnish Co., Inc., collaborated on the development of an abrasion resistant hardcoat for ReflecTech Mirror Film. The hardcoat adds a protective shield to the surface of ReflecTech Mirror Film, which is primarily used in utility-scale parabolic trough concentrating solar power (CSP) systems as a high-performance, lower cost alternative to the fragile, curved glass mirrors commonly used in such systems. ReflecTech and Red Spot began developing the hardcoat in mid-2008 as part of a Cooperative Research and Development Agreement (CRADA) with the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL). SkyFuel has completed large-scale trials, and ReflecTech Mirror Film with the abrasion-resistant hardcoat will be commercially available later this year.
Randy Gee, chief technology officer at SkyFuel and co-founder of the company along with Gary Jorgensen, principal scientist, electricity, resources and building systems integration center at National Renewable Energy Laboratory (NREL), said that UV technology was ideal for providing the properties his company sought.
“A the beginning of our product, we took a look at what was available in the marketplace,” Gee said. “We have products that do not include a hardcoat, but the market is much more comfortable with abrasion resistance. We did extensive screening of materials, and Red Spot was really responsive. They were very willing to work with us, providing samples and testing, and ultimately UV came out on top by a large margin. Normally when you have to select the best way to make your product, it would be a difficult decision, but we didn't have that problem.”
“We have primarily been an automotive-based company,” noted Diane Marret, market research project manager, Red Spot Paint & Varnish. “Our PV work came from our headlamp lens development, such as our UVT 200 and UVT 610, which are abrasion resistant, which lends itself to other markets such as PV.”
Patrick Peach, business manager, solar energy products for Red Spot Paint & Varnish, noted that there are improvements that are needed for energy curing to be more attractive to PE end-users.
“There are certainly advantages to UV in terms of processing and being green, but it can only go so far at this time,” Peach said. “There is still work that needs to be done in terms of extended weatherability, adding more functionality, the refractive index and self-cleaning, and these are all being worked on.”
Aside from Ramos’ talk, the sessions also looked at the possibilities for UV/EB and printing. Dr. Michael Holman, research director of Lux Research, offered his latest findings on developments in the PV space in his talk on “The Role of Non-Active Materials and Market Opportunities.” Dr. Holman discussed the various technologies, from crystalline silicon to thin film, and the materials that will play a role in the market’s continued growth.
“There are some good opportunities for printing PV, such as using inkjet for metallization,” Dr. Holman noted.
Josh Oliver of Sartomer analyzed "Influences on Barrier Performance of UV/EB Cured Polymers," a look at key raw material properties and how UV and EB can be used as component in barriers.
During her talk on "Material Needs for Photovoltaic Modules," Sarah Kurtz, principal scientist, National Center for Photovoltaics at NREL, said “there are probably 20 or 30 ways to utilize printing in PV, and there will be different technologies for different applications. For example, a lightweight flexible substrate is desirable for building integrated PV (BIPV). The question for UV is whether a company can reduce cost while improving reliability.”
On the subject of organic PV, Kurtz noted that “organic PV uses mostly low temperature processes, and is being heavily researched at universities.”