ORANIC LIGHT EMITTING DIODE ( OLED )

                           

 PRINCIPLE :

            It is the solid state device made up of thin films of organic molecules that produce light with the application of electricity. An electron moves from the cathode to the emissive layer ( ELECTRON TRANSPORTING LAYER ) and the hole moves from the anode to the conductive layer (HOLE INJECTIVE LAYER ) and they recombine to produce photon ( Light ). 

STRUCTURE : 

1. The OLED consist of a cathode and a anode, in between there are two organic layers present

2. The layers are emissive layer (ELECTRON TRANSPORTING LAYER ) and Conductive layer   (HOLE INJECTION LAYER )

3. All the layers are grown over a transparent substrate through which the light will be emitted.

4. ANODE is connected to the positive terminal and CATHODE is connected to the negative terminal of the battery.

                          

WORKING :

1. Forward bias voltage is applied across the OLED.

2. By apply voltage to the cathode will get negative charge electrons. Then the electrons in the cathode will repel  the electrons in the next layer i.e. (ELECTRON EMITTING LAYER).

3.By apply voltage to the anode will get positive charge holes. Then the holes in the anode will repel the holes in the previous layer i.e. (HOLE INJECTING LAYER ).

4.By the electrostatic force the electron in the ELECTRON EMITTING LAYER attract the holes in the hole injection layer and the recombination take place in the organic emitters .

5. The recombination take place near to the emissive layer of the organic emitters because the movement of the hole is faster in the organic semiconductor.

6.The recombination is result in the production of POTON (Light).The light is pass through the transparent substrate.

                       

OTHER DETAILS :

• OLED is made up of 100 to 500 nm thick.
•  The Organic Light Emitting Diode (OLED) is also called Light Emitting Polymer (LEP) or Organic Electro Luminescence (OEL) and it consist of a film of organic compound.
• eg of ELECTRON TRANSPORTIN LAYER - POLYFLURENE
• eg of HOLE INJECTION LAYER - POLYANILINE