Ppt on Light Emitting Polymer

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.




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




Poly p-

phenylenevinylene

LEP can be used in

Laptop screens, cellphones, TV screens,

calculators, digital

cameras, and in a

future almosteverything.

Light Emitting Polymers




LIGHT EMITTING POLYMER

Schematic of a 2-layer LEP:

1. Cathode (−), 2. Emissive Layer, 3. Emission of radiation, 4. Conductive Layer, 5. Anode (+)

http://en.wikipedia.org/wiki/File:OLED_schematic.svg




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.














http://slidepdf.com/reader/full/ppt-on-light-emitting-polymer 7/27Light emitting polymer

CONSTRUCTION

Anode-Indium Tin Oxide

Cathode- Aluminum

Polymer- poly

phenylene vinylene















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

















INK JET PRINTING







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..
















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.



















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.























BASIC PRINCIPLE AND TECHNOLOGY







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.



























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.





















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.

















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.



























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.














https://webspace.utexas.edu/mes729/WWW/OLEDs/Images/colors.jpg?uniq=vcw2s4




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.













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!








https://webspace.utexas.edu/mes729/WWW/OLEDs/Images/sony_11-inch_oled_profile.jpg?uniq=-yl3on6




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.









https://webspace.utexas.edu/mes729/WWW/OLEDs/Images/0704GWoled_3.jpg?uniq=-yl3l5u




FUTURE DEVELOPMENTS






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”





















https://webspace.utexas.edu/mes729/WWW/OLEDs/Images/th_0609mae_n05_02.jpg?uniq=-cv6x8b




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.






















https://webspace.utexas.edu/mes729/WWW/OLEDs/Images/bown0605SmtHome_485x220.jpg?uniq=-cw74yk



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.



















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















3-Mar-12Light emitting polymer



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