ppt on light emitting polymer
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5/14/2018 Ppt on Light Emitting Polymer - slidepdf.com
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Light emitting polymer
Introduction
LEP
Construction and working
Ink jet printer
Active Matrix and passive MatrixBasic principle and technology
Light emission
Advantages and Disadvantages
Applications
Future application
Conclusion
Bibliography.
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Light emitting polymer
Introduction
After watching the breakfast news on TV, you rollup the set like a large handkerchief, and stuff itinto your briefcase.
Somewhere in the Kargil sector, a platooncommander of the Indian Army readies for theregular satellite updates that will give him thelatest terrain pictures of the border in his sector.
All these are possible using
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Light emitting polymer
Poly p-
phenylenevinylene
LEP can be used in
Laptop screens, cellphones, TV screens,
calculators, digital
cameras, and in a
future almosteverything.
Light Emitting Polymers
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Light emitting polymer
LIGHT EMITTING POLYMER
Schematic of a 2-layer LEP:
1. Cathode (−), 2. Emissive Layer, 3. Emission of radiation, 4. Conductive Layer, 5. Anode (+)
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Light emitting polymer
A voltage is applied across the LEP such that theanode is positive with respect to the cathode. Thiscauses a current of electrons to flow through thedevice from cathode to anode.
Electrostatic forces bring the electrons and theholes towards each other and they recombineliberating light.
In organic semiconductors holes are more mobile
than electrons. The recombination causes a dropin the energy levels of electrons, accompanied by an emission of radiation.
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CONSTRUCTION
Anode-Indium Tin Oxide
Cathode- Aluminum
Polymer- poly
phenylene vinylene
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Light emitting polymer
Light-emitting devices consist of emitting layerssandwiched between a cathode and an anode.
Single-layer devices typically work only under aforward DC bias.
In order to manufacture the polymer, a SPIN-COATING MACHINE is used.
The robot pours the plastic over the rotatingplate, which, evenly spreads the polymer on theplate. This results in an extremely fine layer of the thickness of 100 nanometers.
Once the polymer is evenly spread, it is baked in
an oven to evaporate any remnant liquid
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Light emitting polymer
INK JET PRINTING
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Light emitting polymer
Use of inkjet printing for PLEDdisplaysThis technique is now at theforefront of developments in digitalelectronic materials deposition.Red, green and blue polymersolutions are jetted into well defined
areas with an angle of flightdeviation of less than 5º.The film thickness uniformity may have to be better than ±2 per cent..
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Light emitting polymer
Active matrix
Active Matrix LEP displays are much morecomplex.
Because they have a cathode layer that isan integrated back plane they are able toproduce very high resolution images andhandle large amounts of data at one time.
This display quality is made possible by polysilicone thin-film-transistors whichhave very high current carrying capability and switching speed.
Because of these TFTs, active matrixdisplays have the ability to control eachindividual pixel independently.
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Light emitting polymer
Passive matrix
Passive Matrix LEP displays are thesimplest form of LEP.
These displays are useful inproviding limited information fordevices such as cell phones,
wristwatches, and other simpledisplay applications. Theconstruction of these OLEDs isbased on a set “rib” pattern of thecathode materials and organiclayers.
Drivers at the end of each row orcolumn control where the voltage issupplied, and subsequently whichribs produce the image.
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Light emitting polymer
BASIC PRINCIPLE AND TECHNOLOGY
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Light emitting polymer
The properties of the spherical s orbital and bimodal porbitals combine into four equal , unsymmetrical ,tetrahedral oriented hybridized sp3 orbitals. This is knownas a ‘sigma’ bond
A conjugated ‘pi’ bond refers to a carbon chain or ring whose bonds alternate between single and double (ortriple) bonds. The bonding system tends to form strongerbonds than might be first indicated by a structure with
single bonds
Unlike the ‘sigma’ bond electrons, which are trappedbetween the carbons, the ‘pi’ bond electrons have relativemobility.
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Light emitting polymer
LIGHT EMISSION
Electroluminescence : The energy is released when an electron from the
conduction band falls into a hole in the valence band.
The electronic device that accomplishes this electron-hole interaction is that of a diode, which consists of ann-type material (electron rich) interfaced with p-typematerial (hole rich).
The mobility of electrons and holes are limited to thelinear or branched directions of the molecule. Theefficiency of electron/hole transport between polymermolecules is also unique to polymers.
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Light emitting polymer
Figure demonstration of the full conjugation of π
The delocalized π electron clouds are colored yellow. PPV is a semiconductor. Semiconductors are so called
because they have conductivity that is midway between that of a conductor and an insulator. Semi-conductors require modest amounts of energy
in order to carry a current, and are used intechnologies such as transistors, microchips and
LEDs.
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Light emitting polymer
ADVANTAGES AND DISADVANTAGES
ADVANTAGES Require only 3.3 volts and have lifetime of more than
30,000 hours.
• Low power consumption.
• Self luminous.
• No viewing angle dependence OLED TVs are really thin - the Sony XEL-1 for example is
just 3mm thick. The new prototypes by Sony are merely 0.3mm thick!
OLEDs have a much better viewing angle - almost 180degrees.
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Light emitting polymer
DISADVANTAGES
Because they are made out of organic compounds, somehave a tendency to “die out” before others.“ Reds andblues die first, leaving a very green display”.
Red and green typically last between 10,000 and 40,000hours, while blue compounds begin to die at around1,000 hours. Additionally, the brightness to which yourdisplay is set has a tremendous effect on longevity.
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Light emitting polymer
APPLICATIONS
PHOTOVOLTAICS
PLED technology can be used in reverse, to convertlight into electricity. Devices which convert light
into electricity are called photovoltaic (PV)devices, and are at the heart of solar cells and lightdetectors.
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Light emitting polymer
POLY LED TV
LEPs TVs are really thin - the Sony XEL-1 forexample is just 3mm thick. The new prototypes by Sony are merely 0.3mm thick!
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Light emitting polymer
TRANSPARENT OLEDS
While there seem to be zero to few readily available uses of transparent OLEDs (TOLEDs) inthe consumer market today, the technology exists
for wide spread use in the future.
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Light emitting polymer
FUTURE DEVELOPMENTS
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Light emitting polymer
NEWS AND INFORMATION
Imagine a day when you arereading a newspaper that iscapable of showingpictures and video, iscontinuously updating
itself with the latest news via Wi-Fi connection, andis also so thin and flexiblethat you can roll it up andput it in your backpack orbriefcase.
“That day may someday bea reality thanks to OLEDtechnology”
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Light emitting polymer
ADVANCEMENTS IN THE HOME
One of the many possibilitiesis to replace regular walls or
windows with similar sizedOLED installations which will“lead to user-definable
window spaces".
These walls will usetransparent OLEDs that willmake it possible to havecertain areas opaque whileother areas clear, depending
on what the homeowner would like. Additionally, “the wall can be any color ordesign that you want.
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3-Mar-12Light emitting polymer
Conclusion
Organic electronics are already entering commercial world. Multicolor automobile stereo displays are nowavailable from Pioneer Corp., of Tokyo.Royal Philips Electronics, Amsterdam is gearing up toproduce PLED backlights to be used in LCDs andorganic ICs.The first products using organic displays are already inthe market. And while it is always difficult to predict when and what future products will be introduced
The portable and light weight organic displays willsoon cover our walls replacing the bulky and powerhungry cathode ray tubes.
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Light emitting polymer
Bibliography.
www. cdtltd.co.uk
www. research.philips.com
www. covion.com
www.ieee.com
D.Rwdinger, R.Farshchi and V.Subramanian. “Inkjetpassive component and plastic substrate”. 2003 IEEEDevice Research conference digest pp.187-188, 2003
Josephine B.Lee and Vivek Subramanian. “Ink JetPassive devices” 2003 IEEE Device Researchconference digest, 2003
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3-Mar-12Light emitting polymer