Organic Light-Emitting Diode (OLED) Technology
by James Dunn

Samsung's 40" OLED TV
Photo courtesy Samsung Electronics
Samsung's prototype 40-inch OLED TV


Imagine a device that has a clearer picture then the best HDTV, or allows a phone to be so lightweight and thin that it is unimaginable.  Well that is what the future holds for the new products that will be using OLEDs.  OLED devices are composed of thin films of organic molecules, which emit light when electricity is added, also called electrophosphorescence.  By using different organic materials to these films it creates the primary colors red, green, and blue.  These solid-state semiconductors tend to be less than 500 nm thick, which is about 200 times smaller than a human hair.  OLEDs have either two or three layers of organic material.



There are four main parts that a OLED contains:
Substrate
- This is what supports the OLED and is usually clear plastic, glass, or foil.
Anode
- When current flows through the device then removes electrons, which is also known as adding electron “holes”.
Organic Layers
- This is made of polymers or organic molecules.
        Conducting Layer- This layer is made of organic molecules, such as polyaniline, which transport “holes” from the anode.
        Emissive Layer- This layer is made from another organic molecule, such as polyfluorene, and transports electrons from the cathode.
Cathode
- This is when the light is made the cathode injects electrons when a current flows through the device.  It does not always have to be transparent it just depends on the type of device being used.  (see ref #3: How Stuff Works, 2005)


 OLED structure

photo courtesy how stuff works


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