For the
past few years, scientists at Philips Research have been working
to develop OLEDs as a new light source for homes, workplaces,
stores, public areas, and even cars and planes. It is a light
source that will not only enhance the look and feel of our
interiors, but also – increasingly important – be better for the
environment.
Why OLEDs are lighting’s “next big thing”
Thanks to the benefits OLED lighting panels offer designers,
architects and consumers, we can expect to see these devices
being used in many different contexts in the coming years. For a
start, OLEDs’ homogenous light output, it’s unusual appearance
and low heat emissions make them easy to integrate into other
structures. Interior designers, architects and home-owners will
particularly enjoy the high degree of controllability, which
gives them great freedom in creating lighting concepts or
quickly changing the atmosphere in a room. Consumers will love
the subtle, diffused, dematerialized character of the light
itself and the magical ambience it creates.
Coming soon to a room near you?
Since OLED light is not yet powerful enough to provide full
illumination, it will initially be used for decorative purposes.
However, the range of applications will expand dramatically as
the technology develops. The size of panels is also set to grow:
current prototypes are 5cm x 5cm up to 15cm X 15cm, but already
panels of 60cm X 60cm are envisioned. Philips has developed
plain white and “warm white” panels, while “color-variable”
OLEDs, capable of producing light of almost any color (including
mimicking daylight and traditional lighting), are likely to
appear over the next 3-5 years.
How OLEDs work
Unlike incandescent bulbs, which generate light by passing
electricity through a wire, or fluorescent lamps, which pass
current through a gas, OLED lighting works by passing
electricity through one or more incredibly thin layers of
organic semiconductive layers. These layers are sandwiched
between a negatively charged layer of aluminum, and a positively
charged, transparent layer of indium tin oxide. The whole
“sandwich” is attached to a sheet of glass or other transparent
material, known as a “substrate”. When current is applied to the
aluminum layer, it is conducted to the positive layer through
the organic film. As the current passes through the film, the
film emits light. Different materials in the films emit
different-colored light.
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Windows as lights
Another research focus is on the development of transparent
OLEDs This means OLED panels will be able to function as
ordinary windows during the day, and become panels of light
after dark, either mimicking natural light, or providing
attractive interior lighting. Even during the day, they could
function as privacy shields, in homes or offices. Look out for
transparent OLED panels within the next 3-5 years.
Flexible light
Today’s OLEDs are mounted on glass. In principle, any
transparent substrate would do, but so far only glass has been
able to protect organic films sufficiently from the effects of
moisture and air. However, scientists at Philips Research are
looking for ways to make plastic substrates that will provide
the necessary protection. This opens the way for flexible and
moldable OLED lighting panels, so that, in future, almost any
surface area, flat or curved, could become a light source. We
could see the development of luminous walls, curtains, ceilings
and even furniture. Flexible OLED panels are likely to become
available within 5 to 8 years.
Philips and OLEDs
Philips started its research into OLEDs back in 1991, as part of
the development of OLED display screens. In 2004, in line with
its revised strategy, the company decided to focus on the
lighting applications of OLEDs. Philips is a leader of an
international EU-sponsored project “OLLA” set up in 2004 to
advance basic OLED technology and make it suitable for general
lighting applications.
