One player that remained largely unconsidered in the LED v.
fluorescent/incandescent battle was LED's organic brethren: OLEDs. OLEDs
have many advantages over LEDs -- the ability to flex, improved color, and the
potential to be manufactured by cheaper organic ink printing processes.
However, they also have a couple key disadvantages. One, lifetime, has
been steadily chipped away, and with the first
generation of OLED TV displays, the problem has become almost a
nonissue. However, one key obstacle to OLED lighting remained --
Typically with OLEDs, only 20 percent of the light generated by the
device is emitted. This makes there brightness inferior to LEDs, making them a poor
choice for lighting. However, in a significant breakthrough, researchers
at the University of Michigan and Princeton University have developed an
OLED/microlense combination material that boosts illumination
by over 60 percent, bringing it into the realm of respectability.
The research was led by Stephen Forrest, a professor of electrical engineering
and physics at Michigan, and Yuri Sun, from Princeton University. The
pair observed that in OLEDs light is generated by applying electricity to
a thin organic layer, analogous to the semiconductor in an LED. However
in OLEDs the material character internally reflects the light, forcing it to
run parallel, instead of perpendicularly out of the bulb.
To get the light to come out, researchers first use an organic grid meshed into
the material. The light is guided by this grid to 5 micrometer domed
microlenses, which focus it and project it out as rays.
The results are respectable. The researchers reported that the device
produced 70 lumens per watt, compared with 15 lumens per watt for incandescent
lighting, and 90 lumens per watt for fluorescent lighting. While it might
seem that fluorescent beats the new OLEDs, fluorescent has other problems --
harsh light, less longevity, and the use of environment-damaging substances
The team plans to next scale the technology to more efficient OLED
designs. They are confident the process can be affordably adopted for
mass commercial production.
The DOE is curious about the new technology, seeing as a way to possibly more
affordably reach its LED adoption goals. If LEDs are widely adopted,
according to the DOE, U.S. energy consumption for lighting could be cut to a
third of current levels, resulting in a 10 percent total reduction in power use
and a 258 million metric ton reduction in carbon emissions.
As both LED and OLED technologies are rapidly advancing in terms of production
and efficiencies, it remains to be seen which will ultimately prove themselves
the eventual victor via performance and cost. However, in Professor
Forrest's eyes, the future of OLEDs has never looked better. He is
confident that OLEDs will thrive, and that his team's breakthrough will aid in
that success. He states optimistically, "Luckily, OLEDs are the light
that just keeps giving. There is so much to be done and so much that's
been done, but this is nonetheless a quite exciting advancement."
The team's research will be reported in the August issue of the journal Nature