Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Cost-efficient production process and homogeneous luminosity for OLEDs thanks to micro-scale conductor paths

The trend in lighting technology is towards the large-area and decorative illumination made possible by organic light-emitting diodes (OLEDs).

Analysts at NanoMarkets forecast a worldwide market volume of over $2.9 billion for 2012, with sales increasing to around $5.9 billion by 2014. The lighting industry is now looking for economic production techniques for organic lighting.

In cooperation with Philips, the Fraunhofer Institute for Laser Technology ILT is developing an innovative, cost-efficient process for applying conductor paths to OLEDs.

Organic light-emitting diodes are highly efficient light sources based on organic materials. They achieve high luminous intensity while consuming little energy. OLEDs consist of one or several active organic layers which are energized by two large-area electrodes. The initiated current flow leads to electron-hole recombinations in the organic layer. This produces photons which radiate into the half-space through the conductive, transparent anode - consisting of indium tin oxide (ITO) or similar materials.

To distribute the electrical energy evenly over the entire surface of the OLEDs, metallic conductor paths are applied to the ITO layer. The size of the conductor paths plays an important role here: if they are too wide the paths can affect the luminous homogeneity of the light source. In addition to reducing manufacturing costs for OLEDs, the lighting industry is also very keen to produce tiny geometries. A process is required with which narrow metallic conductor paths can be produced efficiently, resulting in savings of energy and resources.

Up to now the metallic conductor material has been applied to the surface of the OLEDs in an energy-intensive high-vacuum sputter process, in which an atomic layer is deposited over the entire surface of the substrate in a high vacuum and removed again using a photolithographic method in the areas where the conductor paths are not required. This subtractive process is very expensive owing to the effort involved in applying and then removing the metal layer not required, which involves a material loss of up to 90%. Furthermore, the photolithographic removal process is environmentally detrimental as the etching solution containing metals has to be disposed of after use. The conventionally produced conductor paths have a width of up to 120 µm and are therefore optically disruptive to the homogeneous luminosity of the OLEDs.

Additive process will reduce costs and the burden on the environment

The Fraunhofer ILT is now developing a laser technique to apply micro-scale conductor paths for the industrial partner Philips. A mask foil is placed on the surface of the conductor which represents the negative to the conductor path geometry later required. This is then covered by a donor foil whose material will constitute the conductor path, for example aluminum or copper. The assembly is fixed in place and hit with laser radiation traveling at a speed of up to 2.5 m/s along the mask geometry. A mixture of melt drops and vapor forms, which is transferred from the donor foil to the substrate. The solidified mixture produces the conductor path, whose geometry is determined by the mask. As the process takes place in the ambient atmosphere an expensive process chamber is not required. There is no material loss because the residual material of the donor foil can be re-used.

"This enables us to produce narrow metallic paths with adjustable widths between 40 and 100 µm. They exhibit variable thicknesses between 3 and 15 µm and a resistance of

Conductor paths are used wherever electrical energy needs to be conducted over non-conductive surfaces made of glass, silicon or other materials. Further applications derive from the innovative process, including heated windows in cars and other vehicles as well the production of semiconductors for use in solar cells. Considerable demand exists in these sectors for micro-scale conductor paths because wide conductor paths restrict vision in motor vehicles and cause shading which reduces the efficiency of photovoltaic systems.

Contacts at Fraunhofer ILT
Our experts will be pleased to answer any questions:
Dipl.-Ing. Christian Vedder
Surface Engineering Department
Phone +49 241 8906-378
Dr. Konrad Wissenbach
Head of Surface Engineering Department
Phone +49 241 8906-147
Fraunhofer Institute for Laser Technology ILT
Steinbachstrasse 15
52074 Aachen
Phone +49 241 8906-0
Fax +49 241 8906-121

Axel Bauer | Fraunhofer Gesellschaft
Further information:

More articles from Power and Electrical Engineering:

nachricht Fluorescent holography: Upending the world of biological imaging
25.10.2016 | Colorado State University

nachricht Did you know that infrared heating is an essential part of automotive manufacture?
25.10.2016 | Heraeus Noblelight GmbH

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Ice shelf vibrations cause unusual waves in Antarctic atmosphere

25.10.2016 | Earth Sciences

Fluorescent holography: Upending the world of biological imaging

25.10.2016 | Power and Electrical Engineering

Etching Microstructures with Lasers

25.10.2016 | Process Engineering

More VideoLinks >>>