5. semiconductors are very useful devices for amplification of signals, switching, and energy conv
l
6.
7.
8. lThis effect is called electroluminescence and the color of the light (corresponding to the energy
lElectroluminescence-is an optical phenomenon and electrical phenomenon in which a material
lDiscovered in 1907 by the British experimenter H. J. Round of Marconi Labs, using a crystal of
9.
10.
11.
12. lDow Chemical researchers patented a method of preparing electroluminescent cells using high
lElectroluminescence from polymer films was first observed by Roger Partridge at the National P
13.
14.
15. Schematic of a Bilayer OLED
1. Cathode (−), 2. Emissive Layer, 3. Emission of radiation
16. Working principle
lVoltage is applied across the OLED such that the anode is positive w.r.t the cathode.
lA current of electrons flows through the device from cathode to anode, as electrons are injected
lElectrostatic forces bring the electrons and the holes towards each other and they recombine fo
17. lIn organic semiconductors holes are generally more mobile than electrons, results in a relaxatio
lThe frequency of this radiation depends on the band gap i.e (energy gap where no e- exixt) of t
18.
19. lLight weight & flexible plastic substrates
lBy fabricating possiblity of flexible organic light-emitting diodes being fabricated or other new ap
lBetter power efficiency
lOLED element does not produce light or consume power.
lAnd response time is also higher than standard LCD screens.
20. Disadvantages
lCurrent costs
lOLED manufacture currently its extremely expensive.
lLifespan
lThe biggest technical problem for OLEDs was the limited lifetime of the organic materials.
lWater damage
lWater can damage the organic materials so sealing processes are important for practical manu
21.
22. Manufacturers and commercial uses
lOLED technology is used in commercial applications such as displays for mobile phones and p
lOLEDs have been used in most Motorola and Samsung colour cell phones, as well as some HT
lNokia has also introduced some OLED products including the N85 and the N86 8MP, both of w
23. The Google and HTC Nexus One smartphone includes an AMOLED screen, as does HTC's ow
l
Magnified image of the AMOLED screen on the Googl
26. lOn June 25, 2012, Sony and Panasonic announced a joint venture for creating low cost mass pr
lOn December 26, 2011, LG officially announced the "world's largest 55" OLED panel" .
lMitsubishi installed a 6-meter OLED 'sphere' in Tokyo's Science Museum
