Organic Light Emitting Devices is quite similar to
Electro Luminescent Displays
in buildup, consisting of an organic electroluminescent material layered between
two
electrodes:
----------------------------------------
plastic layer
----------------------------------------- Transparent
----------------------------------------- Electrode
Electro luminescent material
-----------------------------------------
----------------------------------------- Electrode
Plastic/ glass substrate
-----------------------------------------
The top electrode is
transparent to allow light to pass through, the bottom
electrode consists of either a
reflective material(To help increase the brightness of
the device), or it consists of a transparent material like the top
electrode. When a current passes through the EL material it emits light.
I belive effect is caused when the
electrons in the
atoms of this material,
wich is forced in to lower orbits by the current, moves ut to their correct orbits
and give of the
energy as light(If this is incorrect, you are welcome to /msg me).
OLEDs with a
fluorescent electro luminescent material have been recharged for
nearly twenty
years now, and have a power efficiency of about 25%, but Universal
Display Corporation(UDC) has patented a type that uses a
phosphorescent material,
with almost 100% efficiency.
By using transparent electrodes and
plastics these devices can be made transparent,
and be used as
overlay displays or by stacking three OLED displays with different
light emitting materials, a
RGB type
colour display can be produced. By using soft
plastics as substrate flexible displays can be made, making it possible to build
display devices that can be rolled up when not in use.
I think this looks like a promising technology, and it can be interesting to see what
it will bring in the future.
Information sources I used for this WU:
UDC's webpages http://www.universaldisplay.com/
IBM, Almaden 's OLED pages http://www.almaden.ibm.com/st/projects/oleds/