Light from Crystals – Light-emitting Diodes Invade our Lives
Dr. rer. nat. Klaus Streubel (Spokesperson)
Dr. rer. nat. Andreas Bräuer
Dr. rer. nat. Stefan Illek Osram Opto Semiconductors GmbH, Regensburg
Fraunhofer-Institut für Angewandte Optik und
Feinmechanik IOF, Jena
Light-emitting diodes (LEDs) have definite advantages over electric light bulbs: they are made to last and consume less energy.
But how can the small and actually poor illuminants be gotten into shape for powerful and ultra-bright applications?
A new way of producing LEDs with much higher luminous intensity than in the past was discovered by Klaus Streubel, Stefan Illek and Andreas Bräuer who devised a new thin-film technology as well as a special package and optics. Klaus Streubel is head of the Conceptual Engineering department at Osram Opto Semiconductors in Regensburg, where Stegan Illek works as a development engineer. Andreas Bräuer is head of the Micro-optical Systems department at the Fraunhofer Institute for Applied Optics and Precision Engineering IOF.
Three innovations for the great objective
The achievement of the three nominated researchers consists of three separate innovations. They were thus able to successfully overcome an obstacle which until now had stood in the way of LED applications. The heart of an LED is a small semiconductor chip that emits light when an electric current is applied. The intensity of the light, however, has so far been low. Consequently, LEDs were only used for applications that did not require bright light: for example, as indicator lights in car instrument panels and as backlighting for cell phone displays.
Streubel and Illek and their team succeeded in improving the performance of LED chips considerably through the use of thin-film technology. They used a special technique: a metal reflector in the chip itself made it more efficient and gave the chip its unique properties. The thin-film technology is used to produce more efficient and larger LED chips which produce much more light than has been possible in the past. The Osram developers invented a new package that can be used to combine chips of different colors. In this way, powerful LEDs are created whose light can be mixed to produce the desired shade of color or white light. Bräuer and his team created a special optical system that bundles the light produced and, depending on the requirements for an application, forms an intensity profile.
LEDs for street lights and headlamps
The findings of the researchers are revolutionizing LED technology. LED light sources can replace conventional lamps in virtually every setting, for example, in television screens, street lights, projectors, and car headlamps. The first products were introduced to the market in 2002. Because of their low power consumption, they help save energy and reduce CO2 emissions which are so harmful to the environment.
Market researchers predict that sales of powerful LEDs will increase by on average 20 percent per year to 11 billion US dollars by 2012. To prepare for this boom, Osram Opto Semiconductors is expanding their production sites for LEDs and plans on investing a three-figure Euro amount in the project.