DRESDEN (dpa) – Organic light emitting displays may be the next monitors in your future. Called OLED for short, organic light emitting displays practically illuminate themselves, which is one reason why their future is so bright.
The displays use thin organic films as light sources. The technology has several advantages over the current liquid crystal display (LCD) monitors.
Yet until there is a major breakthrough in practical application of the technology, it will be some time before OLEDs will dominate their field.
While OLEDs are already in use in a handful of devices, the research labs of electronics firms are struggling with the durability and production processes of these new monitors.
There’s no doubt that the OLED, sometimes also called the organic light-emitting diode, will eventually hit it big, according to experts.
“The displays offer a much higher brightness than current monitors,” says Joerg Amelung, who leads the technology division of the Fraunhofer Institute in Dresden, Germany. He is personally involved with the production of OLEDs.
Kodak is developing OLEDs that weigh only half as much as a similarly sized LCD monitor, the firm claims. They are as thin as a coin and use significantly less power, the company notes.
Another advantage of the OLEDs is in their significantly larger viewable radius. If an LCD user is not positioned directly in front of the LCD screen, the image displayed quickly becomes difficult to recognize.
“OLED offers the user a viewable radius up to 90 degrees at times,” Amelung explains.
That fact alone makes OLED technology applicable for car radios, for example, since the display is generally visible to the driver only from sharp angles. Among the early contestants in the OLED area is the manufacturer Pioneer, which has already used an OLED in its CD tuner DEX-P9R.
As with prior non-organic light diodes, OLEDs require a certain wave length to produce light. Yet OLEDs are surface emitters, which means that not every visible point must be individually controlled, as is the case with thin film transistor (TFT) monitors.
“OLED monitors can be built significantly flatter that previous flat screens,” says Joerg Amelung.
This is because every visible point on a TFT screen must have two transistors behind it to serve as signallers. For OLEDs, as with passive matrix screens, this is not necessary.
The fact that every point on a TFT screen needs to be individually steered makes those devices comparatively more expensive.
It is also very likely that of the millions of visible points, one or another will not work – and this raises the number of rejects in a production line – and hence the price to the end-user.
“Once OLED monitors are finally introduced, and once the manufacturers get production figured out, prices will be around 30- per-cent less that today’s prices for LCD monitors,” explains Olaf Gelsen, director of technology marketing for Covion Organic Semiconductors in Frankfurt, Germany.
Covion provides the film system for OLEDs.
“Since the backlighting of a display is done away with in the OLED technology, you can build film-thin displays that could, for example, contour to the curves of a car’s dashboard,” Amelung explains.
It’s also possible to imagine handheld PCs that could simply be rolled up and stuck into a pocket between use. Televisions might also conceivably take advantage of OLEDs, albeit with an active matrix screen.
Manufacturers distinguish between polymer OLEDs (P-OLEDs) and small-molecule OLEDs (SM-OLEDs). In polymer OLEDs, the illuminating organisms are bound to molecule chains.
“It is imaginable that a P-OLED monitor could be printed onto a transparency,” Amelung claims. “The displays don’t last long enough.” SM-OLEDs have a different problem, namely with the reproduction of full colours.
“We are working within thresholds of 100 to 150 nanometers. This is one ten-thousandth of a millimetre,” Olaf Gelson of Covion explains.
The experts all feel that the problems facing OLEDs can be overcome. “For the production of displays, the use of a vacuum chamber for moisture suppression is required,” a Kodak representative says.
Above all, large surface OLEDs, such as those to be used as computer monitors or televisions, aren’t quite a reality yet. “It will take another two to three years before we can reliably pump out high-resolution OLEDs that can replace today’s desktop monitors,” Gelsen says.
