How do OLEDs Emit Light?

OLEDs emit light in a similar manner to LEDs, through
a process called electrophosphorescence.

The process is as follows:

1. The battery or power supply of the device containing
the OLED applies a voltage across the OLED.
2. An electrical current flows from the cathode to the
anode through the organic layers (an electrical current is
a flow of electrons).
* The cathode gives electrons to the emissive layer
of organic molecules.
* The anode removes electrons from the conductive
layer of organic molecules. (This is the equivalent to giving
electron holes to the conductive layer.)
3. At the boundary between the emissive and the conductive
layers, electrons find electron holes.
* When an electron finds an electron hole, the
electron fills the hole (it falls into an energy level of the
atom that's missing an electron).
* When this happens, the electron gives up energy
in the form of a photon of light.
4. The OLED emits light.
5. The color of the light depends on the type of organic
molecule in the emissive layer. Manufacturers place several
types of organic films on the same OLED to make color
displays.
6. The intensity or brightness of the light depends on the
amount of electrical current applied: the more current, the
brighter the light.