Stable electrodes for improving printed electronics

Apr 19, 2012
After introducing what appears to be a universal technique to reduce the work function of a conductor in printable electronics, a team led by Georgia Tech's Bernard Kippelen has developed the first completely plastic solar cell. Credit: Virginie Drujon-Kippelen

Imagine owning a television with the thickness and weight of a sheet of paper. It will be possible, someday, thanks to the growing industry of printed electronics. The process, which allows manufacturers to literally print or roll materials onto surfaces to produce an electronically functional device, is already used in organic solar cells and organic light-emitting diodes (OLEDs) that form the displays of cellphones.

Although this is expected to grow by tens of billions of dollars over the next 10 years, one challenge is in manufacturing at low cost in . In order to create light or energy by injecting or collecting electrons, printed electronics require conductors, usually calcium, magnesium or lithium, with a low-work function. These metals are chemically very reactive. They oxidize and stop working if exposed to oxygen and moisture. This is why electronics in solar cells and TVs, for example, must be covered with a rigid, thick barrier such as glass or expensive encapsulation layers.

However, in new findings published in the journal Science, Georgia Tech researchers have introduced what appears to be a universal technique to reduce the work function of a conductor. They spread a very of a polymer, approximately one to 10 thick, on the conductor's surface to create a strong surface dipole. The interaction turns air-stable conductors into efficient, low-work function electrodes.

The commercially available polymers can be easily processed from dilute solutions in solvents such as water and methoxyethanol.

"These polymers are inexpensive, environmentally friendly and compatible with existent roll-to-roll mass production techniques," said Bernard Kippelen, director of Georgia Tech's Center for Organic Photonics and Electronics (COPE). "Replacing the reactive metals with stable conductors, including , completely changes the requirements of how electronics are manufactured and protected. Their use can pave the way for lower cost and more flexible devices."

To illustrate the new method, Kippelen and his peers evaluated the polymers' performance in organic thin-film transistors and OLEDs. They've also built a prototype: the first-ever, completely plastic solar cell.

"The polymer modifier reduces the work function in a wide range of conductors, including silver, gold and aluminum," noted Seth Marder, associate director of COPE and professor in the School of Chemistry and Biochemistry. "The process is also effective in transparent metal-oxides and graphene."

Explore further: Artificial muscles get graphene boost

Related Stories

Recommended for you

Artificial muscles get graphene boost

May 22, 2015

Researchers in South Korea have developed an electrode consisting of a single-atom-thick layer of carbon to help make more durable artificial muscles.

How to make continuous rolls of graphene

May 21, 2015

Graphene is a material with a host of potential applications, including in flexible light sources, solar panels that could be integrated into windows, and membranes to desalinate and purify water. But all ...

Carbon nanothreads from compressed benzene

May 20, 2015

A new carbon nanomaterial – the thinnest possible one-dimensional thread that still retains a diamond-like structure – was created by the controlled, slow compression and decompression of benzene. The ...

Printing 3-D graphene structures for tissue engineering

May 19, 2015

Ever since single-layer graphene burst onto the science scene in 2004, the possibilities for the promising material have seemed nearly endless. With its high electrical conductivity, ability to store energy, ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.