OLED TV IN THE FUTURE?
Given the major investments in LCD
and plasma-display panels (PDPs), many
experts wonder if OLED TVs will ever be
able to match LCD and PDP TVs. Right
now, the best answer is that the potential
is out there. However, nearly every OLED
expert agrees that OLED technology for
TVs is still in the formative stage.
Last year’s introduction of the Sony
1.1-mm thin XL-1 11-in. diagonal OLED
TV was a harbinger of this potential (Fig.
5). This year, Sony introduced an even
slimmer version at 0.3 mm and showed
off a prototype 27-in. diagonal OLED TV
monitor capable of displaying video images
in a 1920- by 1080-pixel format.
Sony is not alone. Samsung SDI plans
to produce a 40-in. diagonal OLED TV
by 2010. CMEL claims that it will begin
production of 12.1-in. diagonal OLED
displays for notebook computers in the
first half of next year and volume production of 32-in. diagonal OLED TVs by the
second half of 2009.
The one major challenge involves mastering
the AM OLED manufacturing
process for large-size displays needed in
TVs. AM OLED manufacturing is still an
inefficient process, as yields decrease with
increasing panel sizes. So, at least for the
next couple of years, we can expect OLEDs
to make inroads as displays for portable and
mobile electronic consumer products.
GETTING THE LIGHT OUT
One of the most promising attributes of
OLED technology is its potential as an
efficient white-light source. In fact, display
experts predict that OLEDs may prove
to be serious (and possibly disruptive)
competitors with inorganic LEDs, which
themselves are making rapid advances as
high-efficiency light sources. That can
only happen, though, if most of the light
presently trapped inside an OLED’s layers
(about 60%) can be freed.
So far, efforts look very promising.
One way to accomplish this is by using an
embedded tandem system of low-index
grid and micro lenses. That’s the approach
being tried by researchers at the University
of Michigan to deliver significantly more
bright light than has been possible to date
(Fig. 6). Developed jointly with Princeton
University and funded by Universal Display
Corp. (UDC) and the U.S. Department of
Energy (DOE), their approach has yielded
70 lumens/W compared with 15 lumens/W
for incandescent bulbs.
UDC recently announced a major breakthrough
with a white OLED that has a
power efficacy of 102 lumens/W at 1000 cd/
m2, using UDC’s phosphorescent OLED
(PHOLED) technology. The device provides
operating lifetimes of 8000 hours to
50% of initial luminance. Konica Minolta
recently licensed UDC’s PHOLED technology
to make and sell energy-efficient
white OLED lighting products.
Osram has developed a transparent white
OLED tile. A prototype has achieved luminous
efficiency of 20 lumens/W at a brightness
level of 1000 cd/m2 (Fig. 7). Osram is
already using its OLEDs in home floor
lamps designed by Germany’s Lösche
Design. They’re also being used for table
lamp lighting designed by Ingo Maurer.