Using Vibration to Produce Advanced Organic Thin-film Transistors

The research of Oana Jurchescu, PhD, and Peter Diemer at Wake Forest University in developing organic thin-film transistors has futuristic potential — the ultimate fruits of their efforts for example could be electronics such as huge pull-down HD video screens or videophones with a scrolling display.

So it’s ironic that a key breakthrough in their research came when Diemer, a third-year graduate student, was mowing his lawn the old-fashioned way.

The vibrations from pushing the mower made Diemer recall the way papers at his father’s printing company would arrange in a certain way when shaken. The image kicked in an idea for Diemer, who works in Jurchescu’s laboratory. Jurchescu, an assistant professor of physics at Wake Forest University, conducts research focused on organic electronics.

Jurchescu and Diemer decided to try using vibration to improve radically the quality of organic thin-film transistors being developed in their lab.

They wound up building a device with small audio speakers on top and bottom to gently vibrate a transistor substrate being coated with a chemical solution while sitting in a glass petri dish. The goal was to better distribute molecules from the solution and produce a higher quality organic film.

More than two years since Diemer’s mowing epiphany, the lab work has delivered. Jurchescu was the lead author of a paper in Advanced Materials published online in September 2013 about the process, “Vibration-assisted Crystallization Improves Organic/Dielectric Interface in Organic Thin-Film Transistors.’’ It is going to be the magazine’s cover story when the print edition is published.

The online paper caught the attention of Nature, the prestigious international weekly journal of science, which printed its own item about the research a few weeks later. In addition, the journal Nature Materials also wrote a highlight about the work.

“I really believe this is a big breakthrough in organic device processing,’’ Jurchescu said.

Organic Thin-film Transistors are ‘Flexible’ Electronics

Oana-JurchescuTransistors are one of the key components in electronics devices because they amplify and switch electronic signals. Jurchescu said the field of organic electronics has the potential to change the semiconductor industry because of the low cost, ease of processing and versatility compared to materials used now in electronics applications.

But the possibility of future “flexible’’ electronics — screens that fold or scroll, electronics sewn into clothing, large portable HD devices — depends on developing high performance organic devices such as the thin-film transistors.

What has Dr Jurchescu excited about the vibration-assisted technique is what she and Diemer have seen in the results. “It’s almost the same quality we would get by using vapor-based transistor production methods, but this is at a much lower cost and with a far faster method of production,’’ she said.

For Jurchescu, the promise of the vibration-assisted technique is just the latest good news. Early in 2013, she received a $400,000 National Science Foundation CAREER Award to support her research. And in April 2013, she published a paper in Advanced Materials about a high-performance, organic semiconductor spray paint that can be applied to large-surface areas.

Seeking a Patent and Partners for the Organic Thin-film Transistor Technology

Stephen Susalka, PhD, associate director of commercialization for Wake Forest Innovations, said a patent application has already been filed for the vibration-assisted crystallization technology.

Next up is seeking an industry partner that sees the possibilities of producing an organic thin-film transistor with quality equal to the current standards of crystal transistors. In fact, it is the cost, speed and scalability of the vibration technique in producing the thin-film transistors that has Susalka most excited.

“It’s a novel invention with significant commercialization potential,’’ said Susalka. “It offers a new and more cost-effective way to make transistors.’’

Jurchescu said although the potential is exciting, much research remains. This includes integrating the vibration technique for organic thin-film transistors with other technologies to make it compatible with large-scale electronics, as well as seeing if the idea of vibration-assisted crystallization can be applied to other organic components such as diodes, solar cells and sensors.

“We just try to grow from one idea into the next, build from ideas that work,’’ she said.

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