How is it that such a small and delicate device can emit light on the scale of an LCD - a device far larger in size?
There are three major steps involved in producing light (see figure to the right):
- Step 1: A power supply applies voltage across the OLED sending electrical current flows from the cathode to the anode through the organic layers. The cathode injects electrons into the emissive layer, while removing electrons from the conductive layer.
- Step 2: The removal of electrons from the conductive layer leaves holes that need to be filled by electrons in the emissive layer.
- Step 3: These holes jump to the emissive layer and recombine with electrons. The combination creates energy in the form of light.
The colour of light is dependent on the type of organic molecule in the emissive layer (several types of organic films are placed on the same OLED to make colour displays). The intensity of brightness increases by applying more current through the device.