 Winter 2006 |
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Plastic Panache
COPE aims to be the country’s premier research and educational resource for flexible organic photonic and electronic materials. by T.J. Becker |
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FOR CONSUMERS, plastic is the Rodney Dangerfield of materials, disrespected because it’s so pervasive in modern life.
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Take electronics, where plastic polymers are being developed as semiconductors in light-emitting diodes (LEDs), solar cells and transistors. This means instead of merely forming the packaging or shell for electronic products, organic materials could actually power radio-frequency identification (RFID) tags, computer displays, television screens and other devices.
“Organic polymers, which are based on carbon-containing compounds, have rich diversity,” points out Bernard Kippelen, associate director of Georgia Tech’s Center for Organic Photonics and Electronics (COPE) and a professor in the School of Electrical and Computer Engineering. “With organic materials, you can build very complex molecules, and there are lots of possibilities to tailor their mechanical, optical and electrical properties by tweaking the chemical structure.”
COPE was launched in 2003 by Kippelen, Jean-Luc Brédas, Seth Marder and Joseph Perry – four prominent researchers Georgia Tech recruited from the University of Arizona. The center is focused on development of new organic materials and devices that will advance information technology, energy, biomedical and defense sectors.
Organic accolades
Being able to fine-tune material properties is just one reason why scientists find organic materials so attractive. Compared to inorganics, they’re lighter in weight, present fewer long-term disposal problems and can be inexpensively manufactured. Like ink, organic molecules can be processed at low temperatures using ink-jet printers or roll-to-roll presses and deposited on flexible substrates. Thus, polymers can show up in places not possible for conventional brittle inorganic materials like silicon.
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Imagine electronic screens hung like wallpaper across large, curved surfaces or being able to roll up small displays for easy transport. “A fountain pen might contain a screen that you could unroll to download news and e-mail from the Internet or watch TV,” says Brédas, a Georgia Research Alliance Eminent Scholar and professor at Georgia Tech’s School of Chemistry and Biochemistry.
In photonic applications (where light is used instead of electrons to transmit signals), organics also offer flexibility, low cost of manufacturing, light weight and the ability to tailor molecules for a specific application. What’s more, organic materials provide greater performance because they’re more sensitive to light. Take electro-optics applications where the inorganic material of choice is lithium niobate. Its electro-optic coefficient (response) is about 30 picometers per volt, whereas organic materials have responses that can be 10 times larger, researchers say.
Organic materials also have higher bandwidth, which allows more information to be processed per unit of time. That’s good news for high-performance computing and telecommunications.
“Although the majority of today’s telecom networks are already using fiber-optic cables to transmit information using light, the switching, routing, decoding and processing is typically performed by electronic devices, which creates a bottleneck,” explains Simon Jones, a research scientist at COPE. Moving to all-optical components could increase today’s fastest network speeds by 100 times.
In its first two years, COPE has attracted more than $20 million in external funding, including industry sponsors as well as government agencies. Projects include:
- Featherweight, flexible solar cells that can power anything from RFID tags to laptop computers. In a project funded by the Office of Naval Research (ONR), Kippelen’s group has been increasing the efficiency of next-generation solar cells by using a crystalline organic film of pentacene and C60, a form of carbon known as “buckyballs.”
- Light-emitting diodes (LEDs) that are less expensive and more efficient than incandescent bulbs for solid-state lighting – work that is funded by the Department of Energy and being done in conjunction with General Electric, Princeton University and Cornell University.
- All-optical signal processing. In a project led by Perry and sponsored by the Defense Advanced Research Projects Agency, COPE is developing organic materials with exceptional nonlinear properties (that allow the use of light beams to switch or decode optical information at extraordinary speed). These materials could lead to a new state-of-the-art in telecommunications and computing, as well as image-recognition systems for homeland security.
- Photonic crystal fabrication. COPE is collaborating with another Georgia Tech center, APEX (Advanced Processing-tools for Electromagnetic/acoustic Xtals or crystals) to develop materials and inexpensive tools for the fabrication of 3-D photonic and phononic crystals, which will enable more researchers to build 3-D microstructures.
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In fact, Georgia Tech has been selected as one of three lead universities for the Center on Materials and Devices for Information Technology Research (MDITR), a major initiative of the National Science Foundation.
Collaboration is king
“What makes organic materials both exciting and challenging is that it’s highly multidisciplinary,” Kippelen says. “You need chemists, biochemists, physicists, and electrical and mechanical engineers.”
A physicist by training, Kippelen characterizes materials and builds devices by electronic means whereas Perry, a physical chemist, approaches materials and devices from a molecular optics perspective. Marder, who specializes in synthetic chemistry, makes materials that serve as building blocks for these devices, while Brédas focuses on computational chemistry, using techniques derived from quantum chemistry and condensed-matter physics to study the structure of molecules and polymers.
Because a new molecule or polymer can take weeks or even months to produce, Brédas’ group is often a starting point. “We can evaluate if the molecule is indeed interesting, and then the synthetic chemists can focus on the best targets,” Brédas explains. “When experimental results come back, we can go deeper to understand why something is or isn’t working.”
COPE’s four founders have worked together for more than a decade.
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Marder, COPE’s director, compares the quartet’s collaborative style to a jazz band, where members work without a score, improvising and feeding off each other. “That’s something we’re trying to perpetuate,” Marder says, noting that more than 20 Georgia Tech faculty members are now involved in COPE along with 75 graduate students.
“COPE has brought a lot of excitement to campus,” says Sam Graham, an assistant professor of mechanical engineering. He praises the camaraderie at the center, noting that the Arizona researchers “came with open arms, looking for ways to collaborate with others at Georgia Tech, including junior faculty, as well as senior professors.”
At COPE, Graham is working on a MDITR-related project, where he measures and models properties needed to manufacture and package organic electronic devices. “We’re concerned with how the mechanical response of materials affects a device’s reliability and performance,” he says. “Properties like thermal conductivity enable us to determine how hot the devices become when we put energy into them. Organic devices don’t require as much power, but they don’t transport heat as well as silicon.”
The COPE work has helped Graham learn more than he would have working as a single investigator, he says: “I see how my background can address issues in this emerging field, a field that I probably would have not considered without input from COPE.”
A broad mission
Although research is a driving force at COPE, the center is also focused on ethics training, education and transferring technology. Some of COPE’s research is already being commercialized by two start-up companies, LumoFlex and Focal Point Microsystems.
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Founded by Kippelen, Marder and Perry, LumoFlex is developing organic solar cells for various applications, including RFID tags, and has won a three-year government contract.
Now used primarily for inventory tracking and warehousing, RFID tags could become widespread in consumer products if manufacturing costs were reduced, Kippelen explains. For example, instead of having their purchases rung up individually, grocery shoppers could pass through an electronic reader that would instantly scan all purchases at once.
Focal Point Microsystems, which was launched by Perry and Marder, has developed proprietary two-photon absorption materials and methods for building 3-D micro- and nanostructures. This fabrication technology is faster and less expensive than traditional layer-by-layer approaches. In essence, a laser beam sculpts a pattern that remains after a solvent dissolves areas of the organic material not treated by the light.
Potential commercial applications for Focal Point include integrated circuits, micro-optical devices and biomedical materials. “For example, you could build structures that act as scaffolding to grow and arrange cells,” Perry explains. “Later, as the cells grow, the scaffolding would disintegrate.”
Both LumoFlex and Focal Point Microsystems are members of Georgia Tech’s VentureLab, a program supported by the Georgia Research Alliance that helps accelerate commercialization efforts of faculty and students.
In addition to tech transfer, another COPE priority is to increase minority participation in engineering and the sciences – both from a gender and ethnic perspective. The center has even hired a diversity director, Keith Oden. “We’re trying to enhance diversity at all levels,” Oden says, referring to the recruitment and retention of undergraduates, graduates, postdoctoral scholars and faculty members.
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Among COPE’s educational programs is a summer research experience for undergraduates (REU). Participants are recruited from outside of Georgia Tech, and during the 10-week program, the undergrads work in labs and attend workshops on career opportunities and ethical conduct in research.
“The objective is to give students some hands-on experience and a chance to test the waters before they commit to a career,” says Jones, who last year served as the director of education for MDITR and COPE. Some students have even had their research published in peer-reviewed journals, he adds.
COPE also offers students international exposure. A native of Belgium, Brédas serves as a scientific director for a research group at the University of Mons-Hainaut, where he continues to hold a professorship. The Belgian research group not only shares information with his team at Georgia Tech, but Brédas has also established an exchange program where group members visit each other’s countries for two or three months.
“Part of the goal is not only to have a scientific experience, but also a cultural one, so you learn more about people and places,” says Chad Risko, who worked in Brédas’ research group while earning his Ph.D. from Georgia Tech.
Now doing post-doctoral work at Northwestern University, Risko says that the trip to Belgium wasn’t his only cultural exposure. Members of Brédas’ group at Georgia Tech hail from more than a dozen different countries, as well as different regions of the United States. “It was great to have that blend of people,” Risko explains. “Whether you’re discussing science or politics, you get different viewpoints – and learn what it’s like to live somewhere else.”
Collaboration is also a key theme in COPE’s educational efforts, and many grad students hold joint appointments in different research groups.
“Rather than turn out people who are experts in only one discipline, we’re trying to train a new generation of scientists who are intrinsically multidisciplinary in how they think about problems,” Marder says.
Traditionally chemists and engineers have been trained independently, and as a result, “if you show the chemical structure of a molecule to an engineer or a circuit diagram to a chemist, they’ll probably run away,” Kippelen says. “Interdisciplinary research better prepares students for their future careers. This is especially true at a time when innovation is speeding up so many things.”
CONTACTS:Jean-Luc Brédas at 404-385-4986 or jean-luc.Brédas@chemistry.gatech.edu
Bernard Kippelen at 404-385-5163 or bernard.kippelen@ece.gatech.edu
Seth Marder at 404-385-6048 or seth.marder@chemistry.gatech.edu
Joseph Perry at 404-385-6046 or joe.perry@chemistry.gatech.edu
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Last updated: April 29, 2006