Future light component produced in printing press

Aug 15, 2012

(Phys.org) -- In the August issue of Nature Communications, Professor Ludvig Edman and PhD Andreas Sandström at Umeå University, report that they have produced organic light-emitting electrochemical cells (LECs) using a roll-to-roll compatible process under ambient conditions.

“LECs can thus be produced as inexpensive and large-area extremely thin light-emitting devices for informative displays and, at a later stage, lighting applications”, says Ludvig Edman, Professor in Physics.

Professor Edman’s group at Umeå University is focusing on novel organic compounds (such as light-emitting and conducting polymers and graphene) and develops LECs based on such materials. The researchers have dramatically improved the energy efficiency and lifetime of LECs, as well as demonstrated the unique physics and chemistry behind their operation and have recently enhanced the performance of LECs to a point where lifetime and efficiency make LECs useful for signage applications.

The next step in the development was to ensure that the manufacturing costs can be attractive for commercial applications. The report shows that using solely air-stable materials in a roll-coater apparatus, the team managed to deposit a light-emitting layer and a PEDOT-PSS anode on top of a flexible cathode-coated substrate mounted on a roll by means of a slot-die head. The layers in the produced LEC device were found to be highly uneven, and the layer thickness, for both active layer and anode, was very thick at approximately 1 µm. However, due to the unique self-doping operation of the LEC, the light emitted did not suffer from the rough interfaces, and was in fact found to be very uniform. This feature is ideal for roll-to-roll processes, as the demands of the coating quality can be relaxed thus lowering the costs substantially.

It is notable that all the steps involved, i.e. preparation of inks, the subsequent coating of the constituent layers, and the final device operation all could be executed under ambient air. This shows that the LEC-technology can be used for a low-cost fabrication of large-area light emitting devices under ambient air.

The experiments were carried out in collaboration with Professor Frederik Krebs and Henrik Dam at the Technical University of Denmark, where they have extensive experience of low-cost roll-to-roll fabrication of organic solar cells.

“It was great to work with Frederik Krebs' group so that we quickly could prove that our 10x10 cm2 application techniques for LECs were transferable to roll-to-roll-processing. Thanks to them we have made a rapid technology leap in a very short time”, says Andreas Sandström, PhD student at Umeå University.

Explore further: Team invents microscopic sonic screwdriver

More information: Andreas Sandström, Henrik F. Dam, Frederik C. Krebs, Ludvig Edman: Ambient Fabrication of Flexible and Large-Area Organic Light-Emitting Devices Using Slot-Die Coating. Nature Communications August 14 issue.

Related Stories

Researchers roll out a new form of lighting

Nov 01, 2011

In this month's edition of Physics World, Paul Blom and Ton van Mol from the Holst Centre in Eindhoven describe a way of creating thin, flexible sheets of organic light-emitting diodes (OLEDs) using a cheap, newspaper-style "roll- ...

Stable electrodes for improving printed electronics

Apr 19, 2012

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 ...

Recommended for you

Researchers prove magnetism can control heat, sound

May 28, 2015

Phonons—the elemental particles that transmit both heat and sound—have magnetic properties, according to a landmark study supported by Ohio Supercomputer Center (OSC) services and recently published by ...

How researchers listen for gravitational waves

May 28, 2015

A century ago, Albert Einstein postulated the existence of gravitational waves in his General Theory of Relativity. But until now, these distortions of space-time have remained stubbornly hidden from direct ...

What's fair?: New theory on income inequality

May 27, 2015

The increasing inequality in income and wealth in recent years, together with excessive pay packages of CEOs in the U.S. and abroad, is of growing concern, especially to policy makers. Income inequality was ...

Scientists one step closer to mimicking gamma-ray bursts

May 27, 2015

Using ever more energetic lasers, Lawrence Livermore researchers have produced a record high number of electron-positron pairs, opening exciting opportunities to study extreme astrophysical processes, such ...

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.