05-02-2013, 02:44 PM
ORGANIC LIGHT EMITTING DIODES(VLSI)
ORGANIC LIGHT.pptx (Size: 301.22 KB / Downloads: 30)
What is an OLED ?
An organic light emitting diode (OLED), also organic electro luminescent device (OELD), is a light-emitting diode (LED) whose emissive electroluminescent layer is composed of a film of organic compounds.
This layer of organic semiconductor material is formed between two electrodes, where at least one of the electrodes is transparent.
OLED (Organic Light Emitting Diodes) is a flat display technology, made by placing a series of organic thin films between two conductors. When electrical current is applied, a bright light is emitted. Because OLEDs produce (emit) light they do not require a backlight. This means that OLEDs can be made very thin and very power efficient when compared to LCD
The difference between OLED/LED::
OLED/LED: What’s the diff? Both OLED and LED use the same principle of electroluminescence the optical and electrical phenomenon where certain materials emit light in response to an electric current passing through it OLED Lighter weight Perform at lower efficiencies Less power consumption.
HISTORY OF OLEDS
In 1979 Chin Tang discovered electroluminescence in the research department of Kodak.
During his work with solar cells he observed a blue glow of organic material.
In 1987 Tang and Van Slyke introduced the first light emitting diodes from thin organic layers.
Surface construction of OLED illumination
The construction of OLED consists of laminated organic thin
films laid on top of a substrate .
The organic device is normally constructed of three layers.
An emissive layer is sandwiched between two transport layers
that come into contact with the cathode and
anode respectively.
Light emission principle of OLED illumination
When a voltage is applied to OLED, the holes and the electrons are generated from each of the two electrodes, which have a positive and negative electric charge respectively.
When they recombine in the emissive layer, organic materials make
the emissive layer to turn into a high energy state termed “excitation”.
The light is emitted when the layer returns to its original stability.
Working principle of OLED
Schematic of a 2-layer OLED: 1. Cathode (−), 2. Emissive Layer,
3. Emission of radiation, 4. Conductive Layer, 5. Anode (+)
A typical OLED is composed of an emissive layer,
a conductive layer, a substrate, and both anode and cathode terminals.
The layers are made of organic molecules that conduct electricity.
APPLICATIONS:
1. Car display 2. Car navigation3. Display panel4. Cellular phone.5. Mobile computer.6. Digital camera7. Digital VTR8. House hold machine.9. Game machine
CONCLUSION
Organic Light Emitting Diodes are evolving as the next generation of light sources.
Organic full-color displays may eventually replace liquid crystal displays for use with lap top and even desktop computers. Researches are going on this subject and it is sure that OLED will emerge as future solid state light source.