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MacRobert Award
2002 Winner
CDT - Light-emitting polymers
[News Release]
 In
1989, researchers at Cambridge University
found that passing an electric current
through certain polymers made them emit
light. Cambridge Display Technology (CDT)
was formed in 1992 to commercialise the
technology that evolved from this discovery.
CDT owns the fundamental intellectual
property and expertise in light-emitting
polymers (LEPs), a form of Organic Light
Emitting Diode (OLED). The team of Dr. David
Fyfe, Professor Richard Friend, Dr. Jeremy
Burroughes, Dr. Karl Heeks and Dr. Carl
Towns are responsible for the development of
this technology.
Light-emitting polymer displays are simple
to manufacture, have excellent viewing
properties and promise low cost manufacture.
By altering the chemistry of the polymer(s)
used, it is possible to produce different
colours. Now there is a wide range of
colours available covering the whole visible
spectrum.
Innovation
LEP displays are made
by applying a thin film of the
light-emitting polymer onto a glass or
plastic substrate coated with a transparent
electrode. A metal electrode is sputtered or
evaporated on top of the polymer.
Application of an electric field between
these two electrodes results in emission of
light from the polymer. When a current is
applied to the polymer, electrons from the
cathode migrate through the cell and meet
positive holes migrating from the anode.
When they meet, they form so-called excitons,
and as the electrons drop into the holes,
energy is released as light.
LEPs have a number of
advantages over liquid crystal displays (LCDs);
LEP is an emissive technology, meaning that
it emits light as a function of its
electrical operation. An LEP display
consists solely of the polymer material
manufactured on a substrate of glass or
plastic and does not require additional
elements that LCDs do, e.g. backlights,
filters and polarizers. LEP technology is
very energy efficient and lends itself to
the creation of ultra-thin lighting displays
that will operate at lower voltages.
One of CDT’s key
innovations is the fact that a display can
be created by ink-jet printing light
emitting polymers on to a sheet of glass or
plastic, which offers a very low cost route
to colour displays. As devices can be
manufactured on flexible plastic substrates
it is possible to make displays that have
non-planar shapes.
Commercial Success
CDT’s LEP technology
has already been licensed to world-class
OEMs, including Philips, Seiko Epson, Osram,
Dupont and Delta Electronics, as a route to
making lighter, brighter, less
power-consuming and more responsive displays
for next generation products such as mobile
phones, PDAs and eventually computer
monitors and televisions. Features include
reduced power consumption, size, thickness
and weight, very wide viewing angle,
superior video imaging performance and the
potential to produce displays on plastic
substrates. CDT licensees will make the
technology commercially available in
consumer electronic products this year.
Visit Cambridge Display Technology Ltd website at www.cdtltd.co.uk.
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