Scientists Create Super-Fast 'Organic' Transistors

Researchers at Stanford and the University of Nebraska this week said they have developed the "world's fastest thin-film organic transistors," a breakthrough they said could be used for inexpensive, powerful computer and TV displays.

The thin-film transistors are thought to be able to "operate more than five times faster than previous examples of this experimental technology," the scientists wrote in the current issue of Nature Communications. An improved method used to create such semiconducting material yields transistors "with electronic characteristics comparable to those found in expensive, curved-screen television displays based on a form of silicon technology," they said.

The transistors are "spun" from a solution of carbon-rich molecules and a complementary plastic. Though it is labeled "organic" by the scientific community, such semiconducting material is not limited to compounds derived from living organisms.

Teams at Stanford led by chemical engineering professor Zhenan Bao and at the University of Nebraska-Lincoln led by mechanical and materials engineering Jinsong Huang made some important alterations to how thin-film organic transistors had previously been made.

The process involves dropping a solution onto a spinning platter made of glass to deposit a thin coating of materials on the platter. In this case, the researchers spun their platter faster than usual and coated just a small, postage-stamp sized section of the platter.

"These innovations had the effect of depositing a denser concentration of the organic molecules into a more regular alignment. The result was a great improvement in carrier mobility, which measures how quickly electrical charges travel through the transistor," the researchers said in a statement announcing their findings.

The scientists dubbed the new method "off-center spin coating." While promising, the researchers said they "cannot yet precisely control the alignment of organic materials in their transistors or achieve uniform carrier mobility."

But even at this early stage, the research teams said their off-center spin coating method was creating thin-film transistors capable of performing "much faster" than earlier attempts to produce organic semiconductors and "comparable to the performance of the polysilicon materials used in today's high-end electronics."

The organic transistors are nearly totally see-through—right now, the scientists said their semiconducting material is "90 percent transparent to the naked eye." That has the researchers predicting that their improved method could "lead to the development of inexpensive, high-performance electronics built on transparent substrates such as glass and, eventually, clear and flexible plastics."

The research was funded by the U.S. Defense Advanced Research Projects Agency (DARPA), the Air Force Office of Scientific Research, and the National Science Foundation.