Flexible electronics — like a handheld computer that rolls up like a magazine or a video display embedded in a shirtsleeve — are no longer limited to the realm of sci-fi, but they are still generally too expensive for the consumer market. Part of the problem is that semiconductors — compounds that move electricity between different materials of varying conductivity — tend to be inflexible or brittle.
Organic semiconductors, on the other hand, are composed of hydrogen, oxygen, carbon and other molecules that generally make bendable material. These semiconductors provide a much more attractive choice for flexible tech applications, and a team of researchers has devised an efficient way to apply them: a semiconductor "spray paint."
Oana Jurchescu, an assistant professor of physics at Wake Forest University in North Carolina, developed this novel technique along with her associates Yaochuan Mei, also of Wake Forest, and John Anthony from the University of Kentucky. The organic semiconductor, called triethylgermylethynyl-substituted anthradithiophene (diF-TEG ADT) can rest comfortably on a variety of substances without breaking or compromising its functionality. Furthermore, diF-TEG ADT is inexpensive and conducts electricity efficiently, even when applied over large areas.
"These organic semiconductors are new to us and to the entire organic electronics community," Jurchescu told us. She explained that researchers can prepare diF-TEG ADT in an organic solvent and then spread it in a very thin layer across the desired medium.
"We can put them on plastic, on clothes, on human skin," Jurchescu said. "We have electronics embedded in these areas that can only be addressed by organics." Inorganic semiconductors, often made with silicon, generate very high temperatures and, as a result, don't play nicely with anything that can melt or burn.
Researchers spread the semiconductors via a thin film that comes not from a paint can, but rather a complex process of mixing chemical compounds, diluting and drying them, and creating crystals from the resulting substances. After adding the diF-TEG ADT to an organic solvent, researchers could spread it across glass and measure its effectiveness.
Jurchescu's trials are promising so far, but the semiconductors only worked effectively when spread across a relatively small area. "We want to use organics for large area displays and applications," she said. "Most semiconductors are incapable of addressing those applications." The next step will be to increase the size of the spray paint's effective area. [See also: 10 Sci-Fi Predictions That Came True ]
Semiconductors, Jurchescu believes, are "at the heart of all electronic applications," but she does not envision any one specific technology for her spray paint's future possibilities. "The technology itself is very versatile, and can be applied to so many things," she said. While she expressed interest in making clothes with built-in displays and embedding electronics in skin, Jurchescu also thinks that this technology could help make large solar cells more efficient.
Developing the technology that powers flexible electronics is just as vital as developing the flexible electronics themselves. The next big thing — whatever it turns out to be — may be powered by a sprayable film rather than silicon or gold.