Researchers Create World’s Fastest Organic Transistor

<div class="wp-caption aligncenter" id="attachment_27304" style="background-color: #f8f8f4; border: 1px solid rgb(230, 230, 230); color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin: 10px auto 20px; outline: 0px; padding: 1px; text-align: center; vertical-align: baseline; width: 554px;"> <img alt="Engineers Make Worlds Fastest Organic Transistor" class="size-full wp-image-27304" height="300" src="http://scitechdaily.com/images/Engineers-Make-Worlds-Fastest-Organic-Transistor.jpg" style="background-image: none; border: 0px; margin: 0px; outline: 0px; padding: 4px 0px; vertical-align: baseline;" width="544" /><br /> <div class="wp-caption-text" style="background-color: transparent; border: 0px; font-size: 12px; line-height: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> Transparent transistors on this postage-stamp size glass have speed characteristics rivaling some forms of silicon transistors. The device used a new process to make this world record-setting organic transistor, paving the way for a new generation of cheap, transparent electronic devices. (Jinsong Huang and Yongbo Yuan, University of Nebraska-Lincoln)</div> </div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> <em style="background-color: transparent; border: 0px; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">A team of researchers has created the world’s fastest thin-film organic transistor, operating at more than five times faster than previous examples.</em></div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> Two university research teams have worked together to produce the world’s fastest thin-film organic transistors, proving that this experimental technology has the potential to achieve the performance needed for high-resolution television screens and similar electronic devices.</div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> For years engineers the world over have been trying to use inexpensive, carbon-rich molecules and plastics to create organic semiconductors capable of performing electronic operations at something approaching the speed of costlier technologies based on silicon. The term “organic” was originally confined to compounds produced by living organisms but now extended to include synthetic substances based on carbons and includes plastics.</div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> In the January 8 edition of Nature Communications, engineers from the University of Nebraska-Lincoln (UNL) and Stanford University show how they created thin-film organic transistors that could operate more than five times faster than previous examples of this experimental technology. Some of the work was performed by SLAC National Accelerator Laboratory researchers at the lab’s Stanford Synchrotron Radiation Lightsource (SSRL).</div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> The research teams were led by Zhenan Bao, professor of chemical engineering at Stanford and member of the Stanford Institute for Materials and Energy Sciences, which is run jointly with SLAC; and Jinsong Huang, assistant professor of mechanical and materials engineering at UNL. They used their new process to make organic thin-film transistors with electronic characteristics comparable to those found in expensive, curved-screen television displays based on a form of silicon technology.</div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> They achieved their speed boost by altering the basic process for making thin-film organic transistors.</div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> Typically, researchers drop a special solution, containing carbon-rich molecules and a complementary plastic, onto a spinning platter – in this case, one made of glass. The spinning action deposits a thin coating of the materials over the platter.</div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> In their Nature Communications paper, the collaborators describe two important changes to this basic process.</div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> First they spun the platter faster. Second they only coated a tiny portion of the spinning surface, equivalent to the size of a postage stamp.</div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> 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.</div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> The researchers called this improved method “off-center spin coating.” The process remains experimental, and the engineers cannot yet precisely control the alignment of organic materials in their transistors or achieve uniform carrier mobility.</div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> Even at this stage, off-center spin coating produced transistors with a range of speeds much faster than those of previous organic semiconductors and comparable to the performance of the polysilicon materials used in today’s high-end electronics.</div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> Further improvements to this experimental process could lead to the development of inexpensive, high-performance electronics built on transparent substrates such as glass and, eventually, clear and flexible plastics.</div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> Already, the researchers have shown that they can create high-performance organic electronics that are 90 percent transparent to the naked eye.</div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> Other key members of the research teams included Yongbo Yuan, a postdoctoral associate at UNL’s Nebraska Center for Materials and Nanoscience, Gaurav Giri, a graduate student in chemical engineering at Stanford and Alex Ayzner, a postdoctoral researcher at SSRL. SSRL’s Stefan Mannsfeld, Dennis Nordlund and Michael Toney also contributed to the research.</div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> The work was funded by the U.S. Defense Advanced Research Projects Agency (DARPA), the Air Force Office of Scientific Research and the National Science Foundation.</div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> This article originally appeared on the Stanford School of Engineering website. Tom Abate is a science writer and Associate Director of Communications at Stanford Engineering. Carole Wilbeck of the UNL College of Engineering also contributed to this report.</div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> <strong style="background-color: transparent; border: 0px; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">Publication</strong>: Yongbo Yuan, et al., “Ultra-high mobility transparent organic thin film transistors grown by an off-centre spin-coating method,” Nature Communications 5, Article number: 3005; doi:10.1038/ncomms4005</div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> Source: Tom Abate, Stanford Engineering; SLAC National Accelerator Laboratory</div> <div style="background-color: white; border: 0px; color: #444444; font-family: sans-serif; font-size: 14px; line-height: 19.600000381469727px; margin-bottom: 1.4em; outline: 0px; padding: 0px; vertical-align: baseline;"> Image: Jinsong Huang and Yongbo Yuan, University of Nebraska-Lincoln</div>

Researchers Create World’s Fastest Organic Transistor

Transparent transistors on this postage-stamp size glass have speed characteristics rivaling some forms of silicon transistors. The devic...

Read more »