Featured Research

from universities, journals, and other organizations

Paint-on plastic electronics: Aligning polymers for high performance

Date:
March 24, 2013
Source:
University of Michigan
Summary:
Semiconducting polymers are an unruly bunch, but now engineers have developed a new method for getting them in line that could pave the way for cheaper, greener, "paint-on" plastic electronics.

Kyeongwoon Chung, Macromolecular Science & Engineering PhD Student, sets up the contact coater to align the surfaces properly for the application of high performance plastic semiconductors.
Credit: Joseph Xu, CoE Communications & Marketing

Semiconducting polymers are an unruly bunch, but University of Michigan engineers have developed a new method for getting them in line that could pave the way for cheaper, greener, "paint-on" plastic electronics.

"This is for the first time a thin-layer, conducting, highly aligned film for high-performance, paintable, directly writeable plastic electronics," said Jinsang Kim, U-M professor of materials science and engineering, who led the research published in Nature Materials.

Semiconductors are the key ingredient for computer processors, solar cells and LED displays, but they are expensive. Inorganic semiconductors like silicon require high temperatures in excess of 2,000 degrees Fahrenheit and costly vacuum systems for processing into electronics, but organic and plastic semiconductors can be prepared on a basic lab bench.

The trouble is that charge carriers, like electrons, can't move through plastics nearly as easily as they can move through inorganic semiconductors, Kim said. Part of the reason for this is because each semiconducting polymer molecule is like a short wire, and these wires are randomly arranged.

"Charge mobility along the polymer chains is much faster than between the polymers," Kim said.

To take advantage of the good conduction along the polymers, research groups have been trying to align them into a charge-carrying freeway, but it's a bit like trying to arrange nanoscopic linguine.

Kim's group approached the problem by making smarter semiconducting polymers. They wanted a liquid polymer solution they could brush over a surface, and the molecules would automatically align with one another in the direction of the stroke, assembling into high-performance semiconducting thin-layer films.

First, they designed the polymers to be slippery -- ordinary polymers glom together like flat noodles left in the fridge, Kim said. By choosing polymers with a natural twist, the team kept them from sticking to one another in the solution. But in order to align during the brushstroke, the polymers needed to subtly attract one another. Flat surfaces would do that, so the team designed their polymer to untwist as the solvent dried up.

They stopped the unaligned polymers from forming large chunks by adding flexible arms that extended off to the sides of the flat, wire-like polymer. These arms prevented too much close contact among the polymers while the bulkiness of the arms kept them from snagging on one another. Polymers with these properties will line up in the direction of an applied force, such as the tug of a paintbrush.

"It's a big breakthrough," Kim said. "We established a complete molecular design principle of semiconducting polymers with directed alignment capability."

And it works. The team made molecules that matched their design and built a device for spreading the polymer solution over surfaces such as glass or a flexible plastic film. The force from the silicon blade, moving at a constant speed across the liquid polymer, was enough to align the molecules.

The team then built the semiconducting film into a simple transistor, a version of the electronic components that make up computer processors. The device demonstrated the importance of the polymer alignment by showing that charge carriers moved 1,000 times faster in the direction parallel to the silicon blade's brushstroke than they did when crossing the direction of the stroke.

"By combining the established molecular design principle with a polymer that has a very good intrinsic charge carrier mobility, we believe it will make a huge difference in organic electronics," he said. "We are currently developing a versatile fabrication method in order to realize high-performance and paintable plastic electronics in various length scales from nanometers to meters."

Kim believes that the technique will work equally well with atomic-scale pen nibs or large trowel-like applicators for making electronics of all sizes such as LED displays or light-absorbing coatings for solar cells.

The paper is titled "A molecular design principle of lyotropic liquid-crystalline conjugated polymers with directed alignment capability for plastic electronics."

The work is funded by the U.S. Department of Energy. Two authors of the paper were partly supported by National Science Foundation and WCU program of National Research Foundation of Korea. The university is pursuing patent protection for the intellectual property and is seeking commercialization partners to help bring the technology to market.


Story Source:

The above story is based on materials provided by University of Michigan. Note: Materials may be edited for content and length.


Journal Reference:

  1. Bong-Gi Kim, Eun Jeong Jeong, Jong Won Chung, Sungbaek Seo, Bonwon Koo, Jinsang Kim. A molecular design principle of lyotropic liquid-crystalline conjugated polymers with directed alignment capability for plastic electronics. Nature Materials, 2013; DOI: 10.1038/nmat3595

Cite This Page:

University of Michigan. "Paint-on plastic electronics: Aligning polymers for high performance." ScienceDaily. ScienceDaily, 24 March 2013. <www.sciencedaily.com/releases/2013/03/130324151830.htm>.
University of Michigan. (2013, March 24). Paint-on plastic electronics: Aligning polymers for high performance. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2013/03/130324151830.htm
University of Michigan. "Paint-on plastic electronics: Aligning polymers for high performance." ScienceDaily. www.sciencedaily.com/releases/2013/03/130324151830.htm (accessed July 31, 2014).

Share This




More Matter & Energy News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Britain Testing Driverless Cars on Roadways

Britain Testing Driverless Cars on Roadways

AP (July 30, 2014) British officials said on Wednesday that driverless cars will be tested on roads in as many as three cities in a trial program set to begin in January. Officials said the tests will last up to three years. (July 30) Video provided by AP
Powered by NewsLook.com
7 Ways to Use Toothpaste: Howdini Hacks

7 Ways to Use Toothpaste: Howdini Hacks

Howdini (July 30, 2014) Fresh breath and clean teeth are great, but have you ever thought, "my toothpaste could be doing more". Well, it can! Lots of things! Howdini has 7 new uses for this household staple. Video provided by Howdini
Powered by NewsLook.com
Amid Drought, UCLA Sees Only Water

Amid Drought, UCLA Sees Only Water

AP (July 30, 2014) A ruptured 93-year-old water main left the UCLA campus awash in 8 million gallons of water in the middle of California's worst drought in decades. (July 30) Video provided by AP
Powered by NewsLook.com
Smartphone Powered Paper Plane Debuts at Airshow

Smartphone Powered Paper Plane Debuts at Airshow

AP (July 30, 2014) Smartphone powered paper airplane that was popular on crowdfunding website KickStarter makes its debut at Wisconsin airshow (July 30) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins