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 Researchers use light to remotely control curvature of plastics
23.03.2017 | North Carolina State University

nachricht TU Graz researchers show that enzyme function inhibits battery ageing
21.03.2017 | Technische Universität Graz

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: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>