OLEDABSTRACT

Over the time there are many changes came into the field of output/display devices. In this field

first came the small led displays which can show only the numeric contents. Then came the

heavy jumbo CRTs (Cathode Ray Tubes) which are used till now. But the main problem with

CRT is they are very heavy & we couldn’t carry them from one place to another. The result of

this CRT is very nice & clear but they are very heavy & bulky & also required quiet large area

than anything else. Then came the very compact LCDs (Liquefied Crystal Displays). They are

very lighter in weight as well as easy to carry from one place to the other. But the main problem

with the LCDs is we can get the perfect result in the some particular direction. If we see from

any other direction it will not display the perfect display. To overcome this problems of CRTs &

LCDs the scientist of Universal Laboratories, Florida, United States & Eastman Kodak Company

both started their research work in that direction & the outcome of their efforts is the new

generation of display technologies named OLED (Organic Light Emitting Diode) Technology. In

the flat panel display zone unlike traditional Liquid-Crystal Displays OLEDs are self luminous &

do not require any kind of backlighting. This eliminates the need for bulky & environmentally

undesirable mercury lamps and yields a thinner, more compact display. Unlike other flat panel

displays OLED has a wide viewing angle (up to 160 degrees), even in bright light. Their low

power consumption (only 2 to 10 volts) provides for maximum efficiency and helps minimize

heat and electric interference in electronic devices. Because of this combination of these features,

OLED displays communicate more information in a more engaging way while adding less

weight and taking up less space. Their application in numerous devices is not only a future

possibility but a current reality.

1

LIST OF FIGURES

Figure 1. Demonstration of flexible OLED device 9

Figure 2. Structure of OLED 12

Figure 3. Triplet state 14

Figure 4. Two different way of decay 15

Figure 5. Single organic layer 16

Figure 6. Two organic layer 17

Figure 7. Multilayer organic light emitting diode 17

Figure 8. Recombination region 19

Figure 9. Layer sequence and energy level diagram for OLED 21

Figure 10. OLED Passive matrix 23

2

Figure 11. OLED Active matrix 24

Figure 12. OLED Transparent structure 25

Figure 13. OLED Top emitting structure 26

Figure 14. Foldable OLED 26

Figure 15. White OLED 27

Figure 16. Samsung galaxy round 33

Figure 17. Blackberry Q30 33

Figure 18. Sony XEL-1,World first OLED TV 33

Figure 19. Kodak LS633 34

Figure 20. Turn light flaps 34

Figure 21. Wallpaper lighting 35

Figure 22. Scroll laptop 35

Figure 23. Toshiba ultra thin flexible OLED 35

3

LIST OF TABLES

Table 1: Comparison of organic OLED and LCD 28

4

TABLE OF CONTENTS

Page no.

Certificate..........................................................................................................................ii

Abstract ............................................................................................................................iii

Acknowledgment..............................................................................................................iv

List of Figure ....................................................................................................................vii

List of Table ......................................................................................................................ix

(1) Introduction………………………………………………………………………....8

(2) History……………………………………………………………………………….10

(3) Components of an OLED…………………………………………………………..12

(4) Working Operation………………………………………………………………....14

(5) Types of OLED……………………………………………………………………..22

(6) OLED and LCD comparison…………………........................................................28

(7) Advantages………………………………………………………………………….30

(8) Disadvantages…………………………………………………………………….....31

(9) Current and future OLED Applications………………………………………….33

(10) Efficiency of OLED………………………………………………………………..36

(11) The Organic Future………………………………………………………………..37

(12) Conclusion……………………………………………………………………….....38

References………………………………………………………………………….39

INTRODUCTION5

Scientific research in the area of semiconducting organic materials as the active substance in

light emitting diodes (LEDs) has increased immensely during the last four decades. Organic

semiconductors was first reported in the 60:s and then the materials were only considered to be

merely a scientific curiosity. (They are named organic because they consist primarily of carbon,

hydrogen and oxygen.). However when it was recognized in the eighties that many of them are

photoconductive under visible light, industrial interests were attracted. Many major electronic

companies, such as Philips and Pioneer, are today investing a considerable amount of money in

the science of organic electronic and optoelectronic devices. The major reason for the big

attention to these devices is that they possibly could be much more efficient than today’s

components when it comes to power consumption and produced light. Common light emitters

today, Light Emitting Diodes (LEDs) and ordinary light bulbs consume more power than organic

diodes do. And the strive to decrease power consumption is always something of matter. Other

reasons for the industrial attention are i.e. that eventually organic full color displays will replace

today’s liquid crystal displays (LCDs) used in laptop computers and may even one day replace

our ordinary CRT-screens.

Organic light-emitting devices (OLEDs) operate on the principle of converting

electrical energy into light, a phenomenon known as electroluminescence. They exploit the

properties of certain organic materials which emit light when an electric current passes through

them. In its simplest form, an OLED consists of a layer of this luminescent material sandwiched

between two electrodes. When an electric current is passed between the electrodes, through the

organic layer, light is emitted with a colour that depends on the particular material used. In order

to observe the light emitted by an OLED, at least one of the electrodes must be transparent.

When OLEDs are used as pixels in flat panel displays they have some advantages

over backlit active-matrix LCD displays - greater viewing angle, lighter weight, and quicker

response. Since only the part of the display that is actually lit up consumes power, the most

efficient OLEDs available today use less power.

6

Figure.1 Demonstration of a flexible OLED device

Based on these advantages, OLEDs have been proposed for a wide range of display

applications including magnified micro displays, wearable, head-mounted computers, digital

cameras, personal digital assistants, smart pagers, virtual reality games, and mobile phones as

well as medical, automotive, and other industrial applications.

7

HISTORY

The first observations of electroluminescence in organic materials were in the early 1950s by

André Bernanose and co-workers at the Nancy-Université, France. They applied high-

voltage alternating current (AC) fields in air to materials such as acridine orange, either

deposited on or dissolved in cellulose or cellophane thin films. The proposed mechanism was

either direct excitation of the dye molecules or excitation of electrons.

In 1960, Martin Pope and co-workers at New York University developed ohmic dark-

injecting electrode contacts to organic crystals. They further described the necessary energetic

requirements (work functions) for hole and electron injecting electrode contacts. These contacts

are the basis of charge injection in all modern OLED devices. Pope's group also first observed

direct current (DC) electroluminescence under vacuum on a pure single crystal of anthracene and

on anthracene crystals doped with tetracene in 1963 using a small area silver electrode at 400 V.

The proposed mechanism was field-accelerated electron excitation of molecular fluorescence.

Pope's group reported in 1965 that in the absence of an external electric field, the

electroluminescence in anthracene crystals is caused by the recombination of a thermalized

electron and hole, and that the conducting level of anthracene is higher in energy than the exciton

energy level. Also in 1965, W. Helfrich and W. G. Schneider of the National Research

Council in Canada produced double injection recombination electroluminescence for the first

time in an anthracene single crystal using hole and electron injecting electrodes, the forerunner

of modern double injection devices. In the same year, Dow Chemical researchers patented a

method of preparing electroluminescent cells using high voltage (500–1500 V) AC-driven (100–

3000 Hz) electrically insulated one millimeter thin layers of a melted phosphor consisting of

ground anthracene powder, tetracene, and graphite powder. Their proposed mechanism

involved electronic excitation at the contacts between the graphite particles and the anthracene

molecules.

Electroluminescence from polymer films was first observed by Roger Partridge at

the National Physical Laboratory in the United Kingdom. The device consisted of a film of

poly(n-vinylcarbazole) up to 2.2 micrometers thick located between two charge injecting

electrodes. The results of the project were patented in 1975 and published in 1983.

8

The first diode device was reported at Eastman Kodak by Ching W. Tang and Steven

Van Slyke in 1987. This device used a novel two-layer structure with separate hole transporting

and electron transporting layers such that recombination and light emission occurred in the

middle of the organic layer. This resulted in a reduction in operating voltage and improvements

in efficiency and led to the current era of OLED research and device production.

Research into polymer electroluminescence culminated in 1990 with J. H. Burroughes et

al. at the Cavendish Laboratory in Cambridge reporting a high efficiency green light-emitting

polymer based device using 100 nm thick films of poly(p-phenylene vinylene).

9

COMPONENTS OF AN OLED

The components in an OLED differ according to the number of layers of the organic material.

There is a basic single layer OLED, two layer and also three layer OLED’s. As the number of

layers increase the efficiency of the device also increases. The increase in layers also helps in

injecting charges at the electrodes and thus helps in blocking a charge from being dumped after

reaching the opposite electrode. Any type of OLED consists of the following components.

1. An emissive layer

2. A conducting layer

3. A substrate

4. Anode and cathode terminals.

Figure.2 Stucture of OLED

Substrate- The substrate supports the OLED.

Example: clear plastic, glass, foil.

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Anode- The anode removes electrons when current flows through the device.

Example: indium tin oxide

Organic layers- These layers are made of organic molecules or polymers.

o Conductive layer- This layer is made of organic plastic molecules that

send electrons out from the anode.

Example: polyaniline, polystyrene

o Emissive layer- This layer is made of organic plastic molecules

(different ones from the conducting layer) that transport electrons from

the cathode; this is where light is made.

Example: polyfluorine, Alq3

Cathode- The cathode injects electrons when a current flows through the device. (It may

or may not be transparent depending on the device)

Example: Mg, Al, Ba, Ca

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WORKING OPERATION

The organic light emitting diode (OLED) is a p-n diode, in which charge-carriers (e-h pairs)

recombine to emit photons in an organic layer. The thickness of this layer is approximately 100

nm (experiments have shown that 70 nm is an optimal thickness). When an electron and a hole

recombine, an excited state called an exciton is formed. Depending on the spin of the e-h pair,

the excitation is either a singlet or a triplet. An electron can have two different spins, spin up and

spin down. When the spin of two particles is the same, they are said to be in a spin-paired, or a

triplet state, and when the spin is opposite they are in a spin-paired singlet state.

Figure.3 Triplet State

On the average, one singlet and three triplets are formed for every four electron-hole pairs, and

this is a big inefficiency in the operation of the diodes. A singlet state decays very quickly,

within a few nanoseconds, and thereby emits a photon in a process called fluorescence. A triplet

state, however, is much more long-lived (1 ms - 1 s), and generally just produce heat. One

method of improving the performance is to add a phosphorescent material to one of the layers in

12

the OLED. This is done by adding a heavy metal such as iridium or platinum. The excitation can

then transfer its energy to a phosphorescent molecule which in turn emits a photon. It is however

a problem that few phosphorescent materials are efficient emitters at room temperature.

Figure.4 Two different ways of decay

There have been devices manufactured which transforms both singlet and triplet states in a host

to a singlet state in the fluorescent dye. This is done by using a phosphorescent compound which

both the singlets and triplets transfer their energy to, after which the compound transfer its

energy to a fluorescent material which then emits light.

Using one organic layer has some problems associated with it. The electrodes energy

levels have to be matched very closely, otherwise the electron and hole currents will not be

properly balanced. This leads to a waste in energy since charges can then pass the entire structure

13

without recombining, and this lowers the efficiency of the device. With two organic layers, the

situation improves dramatically. Now the different layers can be optimized for the electrons and

holes respectively. The charges are blocked at the interface of the materials, and “waits” there for

a “partner”.

Figure.5 Single Organic layer

Considerably better balance can be achieved by using two organic layers one of which is

matched to the anode and transports holes with the other optimized for electron injection and

transport. Each sign of charge is blocked at the interface between the two organic layers and tend

to "wait" there until a partner is found.

Recombination therefore occurs with the excitation forming in the organic material

with the lower energy gap. The fact that it forms near the interface is also beneficial in

preventing quenching of the luminescence that can occur when the excitation is near one of the

electrodes.

14

Figure.6 Two Organic layers

Another improvement is to introduce a third material specifically chosen for its

luminescent efficiency. Now the three organic materials can be separately optimized for electron

transport, for hole transport and for luminescence.

Figure.7 Multilayer organic light emitting diode

The principle of operation of organic light emitting diodes (OLEDs) is similar to that of

inorganic light emitting diodes (LEDs). Holes and electrons are injected from opposite contacts

into the organic layer sequence and transported to the emitter layer. Recombination leads to the

formation of singlet excitons that decay radiatively. In more detail, electroluminescence of

15

organic thin film devices can be divided into five processes that are important for device

operation:

(a) Injection: Electrons are injected from a low work function metal con-tact, e. g. Ca or Mg.

The latter is usually chosen for reasons of stability. A wide-gap transparent indium-tin-oxide

(ITO) or polyaniline thin film is used for hole injection. In addition, the efficiency of carrier

injection can be improved by choosing organic hole and electron injection layers with a low

HOMO (high occupied molecular orbital) or high LUMO (lowest unoccupied molecular orbital)

level, respectively.

(b) Transport: In contrast to inorganic semiconductors, high p- or n-conducting organic thin

films can only rarely be obtained by doping. Therefore, preferentially hole or electron

transporting organic compounds with sufficient mobility have to be used to transport the charge

carriers to the re-combination site. Since carriers of opposite polarity also migrate to some

extent, a minimum thickness is necessary to prevent non-radiative recombination at the opposite

contact. Thin electron or hole blocking layers can be inserted to improve the selective carrier

transport.

(c) Recombination: The efficiency of electron-hole recombination leading to the creation of

singlet excitons is mainly influenced by the overlap of electron and hole densities that originate

from carrier injection into the emitter layer. Recombination of filled traps and free carriers may

also attribute to the formation of excited states. Energy barriers for electrons and holes to both

sides of the emitter layer allow to spatially confine and improve the recombination process.

(d) Migration and (e) decay: Singlet excitons will migrate with an average diffusion length of

about 20 nm followed by a radiative or non-radiative decay. Embedding the emitter layer into

transport layers with higher singlet excitation energies leads to a confinement of the singlet

excitons and avoids non-radiative decay paths. Doping of the emitter layer with organic dye

molecules allows to transfer energy from the host to the guest molecule in order to tune the

emission wavelength or to increase the luminous efficiency.

16

When biased, charge is injected into the highest occupied molecular

orbital (HOMO) at the anode (positive), and the lowest unoccupied molecular orbital (LUMO) at

the cathode (negative), and these injected charges (referred to as “holes” and “electrons,”

respectively) migrate in the applied field until two charges of opposite polarity encounter each

other, at which point they annihilate and produce a radiative state emitting photons with energy

hf =Eg . The energy gap is the difference between the HOMO and LUMO level of the emitting

layer, and it is largely responsible for the observed color of the light.

Figure.8 Recombination Region

17

Figure.9 Layer sequences and energy level diagrams for OLEDs with (a) single layer, (b) single hetero structure, (c) double hetero structure, and (d)multiplayer structure with separate hole and electron injection and transport layers.

18

TYPES OF OLED

There are several types of OLEDs:

Passive-matrix OLED

Active-matrix OLED

Transparent OLED

Top-emitting OLED

Foldable OLED

19

White OLED

Passive-matrix OLED (PMOLED)

PMOLEDs have strips of cathode, organic layers and strips of anode. The anode strips are

arranged perpendicular to the cathode strips. The intersections of the cathode and anode make up

the pixels where light is emitted. External circuitry applies current to selected strips of anode and

cathode, determining which pixels get turned on and which pixels remain off. Again, the

brightness of each pixel is proportional to the amount of applied current.

PMOLEDs are easy to make, but they consume more power than other types of OLED, mainly

due to the power needed for the external circuitry. PMOLEDs are most efficient for text and

icons and are best suited for small screens (2- to 3-inch diagonal) such as those you find in CELL

PHONES, PDA’s and MP3 Players. Even with the external circuitry, passive-matrix OLEDs

consume less battery power than the LCDs that currently power these devices.

Figure.10 OLED Passive Matrix

20

Active-matrix OLED (AMOLED)

AMOLEDs have full layers of cathode, organic molecules and anode, but the anode layer

overlays a thin film transistor (TFT) array that forms a matrix. The TFT array itself is the

circuitry that determines which pixels get turned on to form an image.

AMOLEDs consume less power than PMOLEDs because the TFT array requires less

power than external circuitry, so they are efficient for large displays. AMOLEDs also have faster

refresh rates suitable for video. The best uses for AMOLEDs are computer monitors, large-

screen TVs and electronic signs or billboards.

21

Figure.11 OLED Active Matrix

Transparent OLED

Transparent OLEDs have only transparent components (substrate, cathode and anode) and,

when turned off, are up to 85 percent as transparent as their substrate. When a transparent OLED

display is turned on, it allows light to pass in both directions. A transparent OLED display can be

either active- or passive-matrix. This technology can be used for heads-up displays.

22

Figure.12 OLED Transparent Structure

Top-emitting OLED

Top-emitting OLEDs have a substrate that is either opaque or reflective. They are best suited to

active-matrix design. Manufacturers may use top-emitting OLED displays in SMART CARDS

23

Figure.13 OLED Top-Emitting Structure

Foldable OLED

Foldable OLEDs have substrates made of very flexible metallic foils or plastics. Foldable

OLEDs are very lightweight and durable. Their use in devices such as cell phones and PDAs can

reduce breakage, a major cause for return or repair. Potentially, foldable OLED displays can be

attached to fabrics to create "smart" clothing, such as outdoor survival clothing with an

integrated computer chip, cell phone, GPS receiver and OLED display sewn into it.

Figure.14 Foldable OLED

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White OLED

White OLEDs emit white light that is brighter, more uniform and more energy efficient than that

emitted by fluorescent lights. White OLEDs also have the true-color qualities of incandescent

lighting. Because OLEDs can be made in large sheets, they can replace fluorescent lights that are

currently used in homes and buildings. Their use could potentially reduce energy costs for

lighting.

Figure.15 White OLED

25

ORGANIC LED AND LIQUID CRSYTAL DISPLAY COMPARISON

Organic LED panel Liquid Crystal Panel

A luminous form Self emission of light Back light or outside light is

necessary

Consumption of Electric

power

It is lowered to about mW

though it is a little higher

than the reflection type

liquid crystal panel

It is abundant when back light

is used

Colour Indication form The fluorescent material of

RGB is arranged in order

and or a colour filter is

used.

A colour filter is used.

High brightness 100 cd/m2 6 cd/m2

The dimension of the panel Several-inches type in the

future to about 10-inch

type.Goal

It is produced to 28-inch type in

the future to 30-inch type.Goal

Contrast 100:14 6:1

The thickness of the panel It is thin with a little over

1mm

When back light is used it is

thick with 5mm.

The mass of panel It becomes light weight

more than 1gm more than

the liquid crystal panel in

the case of one for

portable telephone

With the one for the portable

telephone.10 gm weak degree.

Answer time Several us Several ns

A wide use of temperature

range

86 *C ~ -40 *C ~ -10 *C

The corner of the view Horizontal 180 * Horizontal 120* ~ 170*

26

ADVANTAGES OF OLED

The different manufacturing process of OLEDs lends itself to several advantages over flat-panel

displays made with LCD technology.

Lower cost in the future: OLEDs can be printed onto any suitable substrate by an inkjet

printer or even by screen printing, theoretically making them cheaper to produce than

LCD or plasma display. However, fabrication of the OLED substrate is more costly than

that of a TFT LCD, until mass production methods lower cost through scalability.

Light weight & flexible plastic substrates: OLED displays can be fabricated on flexible

plastic substrates leading to the possibility of flexible organic light-emitting diodes being

fabricated or other new applications such as roll-up displays embedded in fabrics or

clothing.

Wider viewing angles & improved brightness: OLEDs can enable a greater artificial

contrast ratio (both dynamic range and static, measured in purely dark conditions) and

viewing angle compared to LCDs because OLED pixels directly emit light.

Better power efficiency: LCDs filter the light emitted from a back light

Response time: OLEDs can also have a faster response time than standard LCD screens.

27

DISADVANTAGES OF OLED

OLED seem to be the perfect technology for all types of displays; however, they do have some

problems, including:

Outdoor performance: As an emissive display technology, OLEDs rely completely

upon converting electricity to light, unlike most LCDs which are to some extent reflective

Power consumption: While an OLED will consume around 40% of the power of an

LCD displaying an image

Screen burn-in: Unlike displays with a common light source, the brightness of each

OLED pixel fades depending on the content displayed. The varied lifespan of the organic

dyes can cause a discrepancy between red, green, and blue intensity. This leads to image

persistence, also known as burn in

UV sensitivity: OLED displays can be damaged by prolonged exposure to UV light. The

most pronounced example of this can be seen with a near UV laser (such as a Bluray

pointer) and can damage the display almost instantly with more than 20mW leading to

dim or dead spots where the beam is focused.

Lifetime - While red and green OLED films have longer lifetimes (46,000 to 230,000

hours), blue organics currently have much shorter lifetimes (up to around 14,000 hours

Manufacturing - Manufacturing processes are expensive right now.

Color balance issues: Additionally, as the OLED material used to produce blue light

degrades significantly more rapidly than the materials that produce other colors, blue

light output will decrease relative to the other colors of light. This differential color

28

output change will change the color balance of the display and is much more noticeable

than a decrease in overall luminance.

Water damage: Water can damage the organic materials of the displays. Therefore,

improved sealing processes are important for practical manufacturing. Water damage

may especially limit the longevity of more flexible displays.

CURRENT AND FUTURE OLED APPLICATIONS

Currently, OLEDs are used in small screen devices like cell phones, digital cameras etc.

29

Some examples of OLED applications are as follows:

Mobile Phones- Mobile phones were the first to adopt AMOLED displays and is the

largest market for OLEDs today.

Figure.16 Samsung Galaxy Round Figure.17 Blackberry Q30

OLED TVs- OLED TVs had begun shipping in 2013 but their prices are still very high.

Figure.18 Sony XEL-1, world’s 1st OLED TV

30

Digital Cameras- Several compact and high-end cameras use AMOLED displays that

offer rich colors and high contrast and brightness. Kodak was the first to release a digital

camera with an OLED display in March 2003, the EasyShare LS633.

Figure.19 Kodak LS633

OLED Lamps- OLED lamps are currently very expensive, but already several

companies are offering these in the premium lighting category.

Figure.20 Turn lights flaps

Other devices- OLEDs are also used in wrist watches, headsets, car audio systems,

remote controllers, digital photo frames and many other kinds of devices.

Future uses of OLED-

Wallpaper lighting defining new ways to light a space

31

Figure.21 Wallpaper Lighting

Scroll Laptop

Figure.22 Scroll Laptop

Rollable OLED television

Figure.23 Toshiba ultra thin flexible OLED

32

Efficiency of OLEDRecent advantages in boosting the efficiency of OLED light emission have led to the possibility

that OLEDs will find early uses in many battery-powered electronic appliances such as cell

phones, game boys and personal digital assistants. Typical external quantum efficiencies of

OLEDs made using a single fluorescent material that both conducts electrons and radiates

photons are greater than 1 percent. But by using guest-host organic material systems where the

radiative guest fluorescent or phosphorescent dye molecule is doped at low concentration into a

conducting molecular host thin film, the efficiency can be substantially increased to 10 percent

or higher for phosphorescence or up to approximately 3 percent for fluorescence.

Currently, efficiencies of the best doped OLEDs exceed that of incandescent light bulbs.

Efficiencies of 20 lumens per watt have been reported for yellow-green-emitting polymer

devices and 40 lm/W for a typical incandescent light bulb. It is reasonable to that of

fluorescent room lighting will be achieved by using phosphorescent OLEDs.

The green device which shows highest efficiency is based on factris(2-phenylpyridine)

iridium[Ir(PPY)3],a green electro phosphorescent material. Thus phosphorescent emission

originates from a long-lived triplet state.

The Organic Future

33

The first products using organic displays are already being introduced into the market place. And while it

is always difficult to predict when and what future products will be introduced, many manufacturers are

now working to introduce cell phones and personal digital assistants with OLED displays within the next

one or two years. The ultimate goal of using high-efficiency, phosphorescent, flexible OLED displays in

lap top computers and even for home video applications may be no more than a few years into future.

However, there remains much to be done if organics are to establish a foothold in the display

market. Achieving higher efficiencies, lower operating voltages, and lower device life times are

all challenges still to be met. But, given the aggressive worldwide efforts in this area, emissive

organic thin films have an excellent chance of becoming the technology of choice for the next

generation of high-resolution, high-efficiency flat panel displays.

In addition to displays, there are many other opportunities for application of organic thin-film

semiconductors, but to date these have remained largely untapped. Recent results in organic

electronic technology that may soon find commercial outlets in display black planes and other

low-cost electronics.

CONCLUSION

34

Performance of organic LEDs depend upon many parameters such as electron and hole

mobility, magnitude of applied field, nature of hole and electron transport layers and excited

life-times. Organic materials are poised as never before to transform the world IF circuit and

display technology. Major electronics firms are betting that the future holds tremendous

opportunity for the low cost and sometimes surprisingly high performance offered by organic

electronic and optoelectronic devices.

Organic Light Emitting Diodes are evolving as the next generation of light

sources. Presently researchers have been going on to develop a 1.5 emitting device. This

wavelength is of special interest for telecommunications as it is the low-loss wavelength for

optical fibre communications. Organic full-colour 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.

REFERENCES

35

1) http://impnerd.com/the-history-and-future-of-oled

2) http://jalopnik.com/5154953/samsung-transparent-oled-display-pitched-as-automotive-hud

3) http://optics.org/cws/article/industry/37032 

4) http://www.cepro.com/article/study_future_bright_for_oled_lighting_market/

5) http://www.oled-research.com/oleds/oleds-history.html

6) http://www.pocket-lint.com/news/news.phtml/23150/24174/samsung-say-oled-not-

ready.phtml

7) http://www.technologyreview.com/energy/21116/page1/ 

8) http://www.voidspace.org.uk/technology/top_ten_phone_techs.shtml#keep-your-eye-on-

flexible-displays-coming-soon

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