As shown in Fig. any type of OLED is made of
the following components
1. An emissive layer.
2. A conducting layer.
3. A substrate.
4. Anode and cathode terminals.
The emissive layer and the conducting layer both are made up of organic molecules of different materials.
These molecules has a property of conducting electricity and their conduction level can be varied substantially.
The emissive layer is made up of organic plastic material (typically polyfluorene)
The conducting layer is also made up of organic molecules (typically polyaniline)
The substrate is made of plastic, foil or glass.The material used for the anode is Indium Tin Oxide, because this material is transparent to visible light.
The cathode component is made from metals like Calcium or Aluminium and the cathode also can be transparent.
The purpose of using various component of OLED have been listed below:
Substrate:To support the OLED
Anode:To inject more holes
Conducting layer :To carry holes from the anode
Cathode:To produce electrons
Emissive layer:To produce light.
A positive voltage is applied to the anode with respect to cathode. Hence an electron produced by the cathode flows to anode.
This electron is captured by the emissive layer due to which the anode withdraws an electron from the conductive layer. Thus a hole is created in the conductive layer.
As this process continues, the conductive layer becomes positively charged (full of holes) and the emissive layer is negatively charged (full of electrons)
Due to electrostatic forces, these electrons and holes combine together very close to the emissive layer to produce light in the emissive region.
This is a visible light, the colour of which depends on the type of organic molecules used. A colour display can be obtained by using a number of organic layers.
The intensity of an OLED display increases with increase in current.