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

18.11.2009
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
christian.vedder@ilt.fraunhofer.de
Dr. Konrad Wissenbach
Head of Surface Engineering Department
Phone +49 241 8906-147
konrad.wissenbach@ilt.fraunhofer.de
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:
http://www.ilt.fraunhofer.de

More articles from Power and Electrical Engineering:

nachricht In best circles: First integrated circuit from self-assembled polymer
19.02.2018 | Max-Planck-Institut für Polymerforschung

nachricht System draws power from daily temperature swings
16.02.2018 | Massachusetts Institute of Technology

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: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Contacting the molecular world through graphene nanoribbons

19.02.2018 | Materials Sciences

When Proteins Shake Hands

19.02.2018 | Materials Sciences

Cells communicate in a dynamic code

19.02.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>