OLEDs

Imagine having a high-definition TV that is 80 inches wide
and less than a quarter-inch thick, consumes less power than
most TVs on the market today and can be rolled up when you're
not using it. What if you could have a "heads up" display in
your car? How about a display monitor built into your
clothing? These devices may be possible in the near future
with the help of a technology called organic light-emitting
diodes (OLEDs).

OLEDs are solid-state devices composed of thin films of
organic molecules that create light with the application of
electricity. OLEDs can provide brighter, crisper displays on
electronic devices and use less power than conventional
light-emitting diodes (LEDs) or liquid crystal displays
(LCDs) used today.

OLED Components

Like an LED, an OLED is a solid-state semiconductor device
that is 100 to 500 nanometers thick or about 200 times
smaller than a human hair. OLEDs can have either two layers
or three layers of organic material; in the latter design,
the third layer helps transport electrons from the cathode to
the emissive layer. In this post, we'll be focusing on the
two-layer design.


An OLED consists of the following parts:

* Substrate (clear plastic, glass, foil) - The substrate
supports the OLED.
* Anode (transparent) - The anode removes electrons (adds
electron "holes") when a current flows through the device.
* Organic layers - These layers are made of organic
molecules or polymers.
o Conducting layer - This layer is made of organic
plastic molecules that transport "holes" from the anode. One
conducting polymer used in OLEDs is polyaniline.
o Emissive layer - This layer is made of organic
plastic molecules (different ones from the conducting layer)
that transport electrons from the cathode; this is where
light is made. One polymer used in the emissive layer is
polyfluorene.
* Cathode (may or may not be transparent depending on the
type of OLED) - The cathode injects electrons when a current
flows through the device.