Light Emitting Polymers (LEPs) are
semi-conducting devices that exhibit electroluminescent characteristics. The
phenomenon known as electroluminescence (EL) is caused by the emission of light
generated from the recombination of electrons and holes electrically injected
into a semi-conductor. So far conventional and marketable electroluminescent
devices (ED s) have always been inorganic semi-conductors but recent
developments in the late 1990s are opening the doors for organic materials.
Introduction
Polymer light emitting diodes (PLEDs)
are optoelectronic devices ctric current flow through them. A simple PLED
consist of a fluorescent polymer layer sandwiched between two metal electrodes. Under
application of an electric field electrons and holes are injected from the two
electrodes in to the polymer layer, where they meet and recombine to produce
light. They have been developed for application in flat panel displays.
Envision light weight, portable and flexible flat panel displays that provide
visual imagery that is easy to read, vibrant in colour and less consuming of
power.
A
typical polymer LED
consists of a
thin film of
a luminescent conjugated polymer sandwiched between an
anode and a cathode, on top of a glass substrate. Indium Tin Oxide (ITO) is
most frequently used as the anode because it exhibits conductive properties
with a relatively high work function. It also is optically transparent, thus
allowing the light to propagate through the device.
Contents
1. Introduction
2. Evelution Of Pled
3. Construction
4. How Pled Works
4.1 Bonding In Lep
4.2 Energy Level Diagram Of Lep
5. P Ledand Lcd
Comparison
And etc
Dot Matrix Displays
A full-color display requires the
patterning of individual red, green, and blue pixels. This is usually a
technologically complicated process, but because LEPs can be deposited from
solution, patterning using a wide variety of printing techniques is possible.
The most advanced technique is ink-jet printing . CDT have demonstrated
resolutions as high as 360 dpi, and it is likely that much higher resolutions
will be obtained in the near future. The inkjet approach is easily scaled to
large-screen displays.
Future
LEP technology combines simple
solid-state construction, low drive voltage, and high-efficiency OLEDs with
large-area pattern ability and the possibility of flexible substrates. This
combination of characteristics provides a powerful base for building high-information-content
displays ranging from micro emissive displays to large-area screens. We expect
that LEP technology will initially be used to extend the performance of current
displays in mobile communications, computers, and consumer electronics but will
quickly lead to new applications.
Abstract
Today most of
electronics circuits are integrated circuits/semiconductor chips fabricated out
of silicon.There are some institutions comes out with plastic circuits that
are used as the electronic circuits. This field of electronics is termed as polytronics .We think of plastics more as insulators
rather than electricity conducting materials. But of late, research institutes
have come up with innovative ideas to integrate plastics into main stream
electronics as it has been established that certain plastics have typical
conductive and light emitting properties.
Conclusion
Performance of polymer LEDs depends up
on many parameters such as electron and hole mobility, magnitude of applied
field, nature of hole and electron transport layers and excitation life time.
Polymer materials are poised as never before to transform the world of circuit
and display technology.
0 comments: