this is the basic description about OLED Dispaly Technology.

1. DEPARTMENT OF ELECTRONICS ENGINEERING
SCHOOL OF ENGINEERING AND TECHNOLOGY
PONDICHERRY UNIVERSITY
PUDUCHERRY 605014
CREDIT SEMINAR
TOPIC: OLED DISPLAY TECHNOLOGY
SUBMITTED BY :
NAME:
COURSE:
ANIL KUMAR YADAV
M.TECH( ELECTRONICS)
REG. NO: 13304025
SUBMITTED TO:
DR. T.SHANMUGANTHAM
(ASSOCIATE PROFESSOR)

2. Table of content
1. Introduction :
2. Working principle:
3. Types of OLEDs:
4. Material used for oled
5. Foldable or flexible oled
6. Advantage & disadvantage
7. Global Market news
8. Conclusion
9. References

3. Abstract
OLED Flexible displays are an exciting development because of their physical and
performance attributes and their capability to enable new products requiring displays
with unique form factors that the current rigid glass substrate based displays cannot
support. Flexible displays can be very thin, light weight, have unique form factors and
be highly rugged and not prone to breakage on impact unlike rigid and flat glass
substrate based displays. The flexible form factors such as having an arbitrary shape,
ability to be curved, conformal, bendable, and rollable can enable a variety of new
applications and products. In this chapter, we will discuss the various attributes of the
flexible displays, their potential applications, and the display media appropriate for
flexible displays.
Like many electronic devices, the majority of today's smartphones aren't made to
survive abuse. With new display technologies that are currently in development
however, smartphones of the future may be more durable. These new display
technologies enable flexible displays that can be rolled, dropped, squished, and stepped
on without damage.
Although the dream of having a smartphone that can withstand such abuse may seem
far-off, flexible display technology has been in development for a while now. We've seen
prototypes at gadget shows, heard and seen demonstrations on various sites, and
dreamed of the day when we can have our own flexible smartphone. New rumors
suggest our dream may not be too far from reality. In fact, it's possible we could see the
launch of the first flexible phone sometime next year.
Introduction :
An exciting technology has been available in many small devices such as cell phones
and digital camera displays for the last 13 years. Soon it may available for use in larger
standard office and home entertainment displays. The technology is organic light
emitting diode (OLED). It is possible that in the next 2-3 years you may see an 80‖
OLED in your living room or board room that only requires 10 or less volts of power to
operate. OLED display devices use organic carbon-based films, sandwiched together
between two charged electrodes. One is a metallic cathode and the other a transparent
anode, which is usually glass. Online encyclopedia, Wikipedia, defines an organic
compound as ―any member of a large class of chemical compounds whose molecules
contain carbon, with the exception of carbides, carbonates, carbon oxides and gases
containing carbon.‖
An OLED (organic light-emitting diode) is a light-emitting diode (LED) in which
the emissive electroluminescent layer is a film of organic compoundwhich emits light in
response to an electric current. This layer of organic semiconductor is situated between

4. two electrodes. Generally, at least one of these electrodes is transparent. OLEDs are
used to create digital displays in devices such as television screens, computer monitors,
portable systems such as mobile phones, handheld games consoles and PDAs. A
major area of research is the development of white OLED devices for use in solid-state
lighting applications
The basic components of an OLED are:
1. Substrate-This is support for the OLED.
2. Anode-The anode removes electrons when a current flow through the device.
3. Organic layers-These layers are made of organic molecules or polymers.
4. Conducting layer -This layer is made of organic plastic molecules that send
electrons out from the anode.
5. 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.
6. Cathode (may or may not be transparent depending on the type of OLED). The
cathode injects electrons when a current flows through the device.

5. Applying the organic layers to the substrate can be accomplished in three ways:
1. Vacuum Deposition or Vacuum Thermal Evaporation (VTE).
In a vacuum chamber, the organic molecules are evaporated through a slow heat
process and then allowed to condense as thin films onto a cooled substrate. This is a
very inefficient and expensive process.
2. Organic Vapor Phase Deposition (OVPD). This process employs an inert carrier
gas (such as nitrogen) to precisely transfer films of organic material onto a cooled
substrate in a hot-walled,low-pressure chamber. The precise transfer and ability to
better control film thickness translates to lower material cost and higher production
throughput.
3. Inkjet Printing. OLEDs are sprayed onto the substrate the same way our desktop
inkjet printer sprays ink onto paper. This greatly reduces the cost of manufacturing
OLEDs and allows for printing on very large films. This allows for a much lower cost and
larger home displays and PIPD products.
One of the major benefits of OLEDs is their low power consumption when compared to
traditional LEDs or LCDs. OLEDs also do not require backlighting to function, which in
addition to using less power, also lowers manufacturing costs. Even with all the layers
that make up an OLED, this is an emissive technology – meaning it generates its own
light.
An OLED display is very thin and compact, typically has a viewing angle of 160 degrees
and will operate on as little as 2 volts. Imagine today’s typical 60‖ flat-screen display, but
instead of an 8-in. thick, 250-lb. plasma display or a 65-lb. LCD, your 60‖ OLED display
is only 1/2‖ thick and weighs roughly 30 lbs.!
Other OLED advantages over traditional LCDs include:
• Increased brightness
• Faster response time (fast action, live events)
• Greater durability
• Thinner and lighter weight product
• Higher contrast

6. How do OLEDs work?
•
OLED do not have a backlight unlike liquid crystal display (LCD). OLED create
light by the following process: A battery or power supply sends a voltage through
the OLED. An electrical current flows from the cathode to the organic layer and
anode. As explained earlier, the anode removes electrons and adds electron
holes in the conductive layer. Between the organic layers is where electrons fill
the holes and give off energy in the form of photon light.

7. Working principle:
A typical OLED is composed of a layer of organic materials situated between two
electrodes, the anode and cathode, all deposited on a substrate. The organic molecules
are electrically conductive as a result of delocalization of pi electronscaused
by conjugation over all or part of the molecule. These materials have conductivity levels
ranging from insulators to conductors, and therefore are considered organic
semiconductors. The highest occupied and lowest unoccupied molecular orbitals
(HOMO and LUMO) of organic semiconductors are analogous to
the valence and conduction bands of inorganic semiconductors.
Originally, the most basic polymer OLEDs consisted of a single organic layer. One
example was the first light-emitting device synthesised by J. H. Burroughes et al., which
involved a single layer of poly(p-phenylene vinylene). However multilayer OLEDs can
be fabricated with two or more layers in order to improve device efficiency. As well as
conductive properties, different materials may be chosen to aid charge injection at
electrodes by providing a more gradual electronic profile, or block a charge from
reaching the opposite electrode and being wasted.]
Many modern OLEDs incorporate a simple bilayer structure, consisting of a conductive
layer and an emissive layer. More recent developments in OLED architecture improves
quantum efficiency (up to 19%) by using a graded heterojunction.
In the graded heterojunction architecture, the composition of hole and electrontransport materials varies continuously within the emissive layer with a dopant emitter.
The graded heterojunction architecture combines the benefits of both conventional
architectures by improving charge injection while simultaneously balancing charge
transport within the emissive region.
During operation, a voltage is applied across the OLED such that the anode is positive
with respect to the cathode. Anodes are picked based upon the quality of their optical
transparency, electrical conductivity, and chemical stability.]A current of electrons flows
through the device from cathode to anode, as electrons are injected into the LUMO of
the organic layer at the cathode and withdrawn from the HOMO at the anode. This latter
process may also be described as the injection of electron holes into the HOMO.
Electrostatic forces bring the electrons and the holes towards each other and they
recombine forming an exciton, a bound state of the electron and hole. This happens
closer to the emissive layer, because in organic semiconductors holes are generally
more mobile than electrons. The decay of this excited state results in a relaxation of the
energy levels of the electron, accompanied by emission of radiation whose frequency is
in thevisible region. The frequency of this radiation depends on the band gap of the
material, in this case the difference in energy between the HOMO and LUMO.

8. As electrons and holes are fermions with half integer spin, an exciton may either be in
a singlet state or a triplet state depending on how the spins of the electron and hole
have been combined. Statistically three triplet excitons will be formed for each singlet
exciton. Decay from triplet states (phosphorescence) is spin forbidden, increasing the
timescale of the transition and limiting the internal efficiency of fluorescent
devices. Phosphorescent organic light-emitting diodes make use of spin–orbit
interactions to facilitate intersystem crossing between singlet and triplet states, thus
obtaining emission from both singlet and triplet states and improving the internal
efficiency.
Indium tin oxide (ITO) is commonly used as the anode material. It is transparent to
visible light and has a high work function which promotes injection of holes into the
HOMO level of the organic layer. A typical conductive layer may consist
of PEDOT:PSS as the HOMO level of this material generally lies between the
workfunction of ITO and the HOMO of other commonly used polymers, reducing the
energy barriers for hole injection. Metals such as barium and calcium are often used for
the cathode as they have low work functions which promote injection of electrons into
the LUMO of the organic layer.[28] Such metals are reactive, so they require a capping
layer of aluminium to avoid degradation.
Experimental research has proven that the properties of the anode, specifically the
anode/hole transport layer (HTL) interface topography plays a major role in the
efficiency, performance, and lifetime of organic light emitting diodes. Imperfections in
the surface of the anode decrease anode-organic film interface adhesion, increase
electrical resistance, and allow for more frequent formation of non-emissive dark spots
in the OLED material adversely affecting lifetime. Mechanisms to decrease anode
roughness for ITO/glass substrates include the use of thin films and self-assembled
monolayers. Also, alternative substrates and anode materials are being considered to
increase OLED performance and lifetime. Possible examples include single crystal
sapphire substrates treated with gold (Au) film anodes yielding lower work functions,
operating voltages, electrical resistance values, and increasing lifetime of OLEDs.
Single carrier devices are typically used to study the kinetics and charge transport
mechanisms of an organic material and can be useful when trying to study energy
transfer processes. As current through the device is composed of only one type of
charge carrier, either electrons or holes, recombination does not occur and no light is
emitted. For example, electron only devices can be obtained by replacing ITO with a
lower work function metal which increases the energy barrier of hole injection. Similarly,
hole only devices can be made by using a cathode made solely of aluminium, resulting
in an energy barrier too large for efficient electron injection.

9. Types of OLEDs:
There currently are six types of OLED screens, each designed for
a different type of use. The types are:
1. Passive Matrix OLEDs (PMOLEDs) 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 pixelsremain 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 (2to 3-inch diagonal) such as those you find in cell phones, PDAs and MP3 players. Even
with the external circuitry, PMOLEDs consume less battery power than the LCDs that
are currently used in these devices.
A PMOLED display uses a simple control scheme in which you control each row (or
line) in the display sequentially (one at a time). PMOLED electronics do not contain a
storage capacitor and so the pixels in each line are actually off most of the time. To
compensate for this you need to use more voltage to make them brighter. If you have
10 lines, for example, you have to make the one line that is on 10 times as bright (the
real number is less then 10, but that's the general idea).
So while PMOLEDs are easy (and cheap) to fabricate, they are not efficient and the
OLED materials suffer from lower lifetime (due to the high voltage needed). PMOLED

10. displays are also restricted in resolution and size (the more lines you have, the more
voltage you have to use). PMOLED displays are usually small (up to 3" typically) and
are used to display character data or small icons: they are being used in MP3 players,
mobile phone sub displays, etc.
The first OLED products in the market used PMOLEDs - these were MP3 players, subdisplays on cellphones and radio decks for automobiles. The displays were small and
usually with just one or two colors. When AMOLED panels started to emerge in 2007
and 2008 we have seen these larger displays in mobile video players, digital cameras,
mobile phones main displays and even OLED TV sets.
2. Active-matrix OLEDs (AMOLEDs):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 TFTarray 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.
AMOLED (active-matrix organic light-emitting diode) is a display technology for use
in mobile devices and televisions. OLED describes a specific type of thin-film-display
technology in which organic compounds form the electroluminescent material,
and active matrix refers to the technology behind the addressing of pixels.
As of 2012, AMOLED technology is used in mobile phones, media players and digital
cameras, and continues to make progress toward low-power, low-cost and large-size
(for example, 40-inch) applications

11. An AMOLED display consists of an active matrix of OLED pixels that generate light
(luminescence) upon electrical activation that have been deposited or integrated onto
a thin-film-transistor (TFT) array, which functions as a series of switches to control the
current flowing to each individual pixel. Typically, this continuous current flow is
controlled by at least two TFTs at each pixel (to trigger the luminescence), with one TFT
to start and stop the charging of a storage capacitor and the second to provide
a voltage source at the level needed to create a constant current to the pixel, thereby
eliminating the need for the very high currents required for passive-matrix OLED
operation.
TFT backplane technology is crucial in the fabrication of AMOLED displays. The two
primary TFT backplane technologies, namely polycrystalline silicon (poly-Si)
and amorphous silicon (a-Si), are used today in AMOLEDs. These technologies offer
the potential for fabricating the active-matrix backplanes at low temperatures (below
150°C) directly onto flexible plastic substrates for producing flexible AMOLED displays

12. 3. Transparent OLEDs have only transparent components (substrate, cathode and
anode) and, when turned off, are up to 85% 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.
4. 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.
5. 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 truecolor 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

13. Foldable or flexible OLEDs
Flexible OLED is an emerging display technology that enables beautiful and efficient
displays and lighting panels. Thin OLEDs are already being used in many mobile
devices and TVs, and the next generation of these panels will be flexible and bendable
Different kinds of flexibility
When we talk about flexible OLEDs, it's important to understand what that means
exactly. A flexible OLED is based on a flexible substrate which can be either plastic,
metal or flexible glass. The plastic and metal panels will be light, thin and very durable in fact they will be virtually shatter-proof.
Flexible 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 sewn into fabrics for ―smart‖ clothing, such as outdoor survival
clothing with an integrated computer chip, cell phone, GPS receiver and OLED display
sewn into it.
Second generation flexible OLED devices may indeed be flexible to the final user.
Finally, when the technology is ready, we may see OLED panels that you can fold, bend
or stretch. This may create all sorts of exciting designs that will enable large displays to
be placed in a mobile device and only be opened when required.

14. Flexible OLED products
After years of research, in October 2013, Samsung announced the world's first product
to use a flexible OLED display - the Galaxy Round curved smartphone. This is an
Android 4.3 smartphone similar to the Galaxy Note 3, with the major feature being the
5.7" Full-HD curved (400 mm curvature radius) flexible display (samsung simply refers
to it as a flexible Super AMOLED, strangely they are not using the YOUM brand)
LG is producing flexible OLED panels, 6" in size. It is expected that LG will also unveil
their own smartphone (called the G Flex) with a flexible OLED towrads the end of 2013.
Initial capacity in both companies is low (a few hundreds of thousands of panels per
month). Samsung's capacity is higher (they are using a Gen-5.5 line and LG is using a
Gen-4.5 line) but this too will not be enough even for a single mass market phone. The
company are probably waiting to see how consumers react to those new panels before
they commit to increase capacity.
Samsung launched their YOUM flexible OLED panels in January 2013, showing some
cool prototypes of curved and flexible OLED displays.

15. Material technologies
Small molecules
Alq3, commonly used in small molecule OLEDs Efficient OLEDs using small molecules
were first developed by Dr. Ching W. Tang et al at Eastman Kodak. The term OLED
traditionally refers specifically to this type of device, though the term SM-OLED is also in use.
Molecules commonly used in OLEDs include organometallic chelates (for example Alq3,
used in the organic light-emitting device reported by Tang et al.), fluorescent and
phosphorescent dyes and conjugated dendrimers. A number of materials are used for
their charge transport properties, for example triphenylamine and derivatives are
commonly used as materials for hole transport layers.[33] Fluorescent dyes can be
chosen to obtain light emission at different wavelengths, and compounds such
as perylene, rubrene and quinacridone derivatives are often used.[34] Alq3 has been
used as a green emitter, electron transport material and as a host for yellow and red
emitting dyes.
The production of small molecule devices and displays usually involves thermal
evaporation in a vacuum. This makes the production process more expensive and of
limited use for large-area devices than other processing techniques. However, contrary
to polymer-based devices, the vacuum deposition process enables the formation of well
controlled, homogeneous films, and the construction of very complex multi-layer
structures. This high flexibility in layer design, enabling distinct charge transport and
charge blocking layers to be formed, is the main reason for the high efficiencies of the
small molecule OLEDs.
Coherent emission from a laser dye-doped tandem SM-OLED device, excited in the
pulsed regime, has been demonstrated. The emission is nearly diffraction limited with a
spectral width similar to that of broadband dye lasers.
Researchers report luminescence from a single polymer molecule, representing the
smallest possible organic light-emitting diode (OLED) device.Scientists will be able to
optimize substances to produce more powerful light emissions. Finally, this work is a
first step towards making molecule-sized components that combine electronic and
optical properties. Similar components could form the basis of a molecular computer.

16. Polymer light-emitting diodes
poly(p-phenylene vinylene), used in the first PLED. Polymer light-emitting diodes (PLED),
also light-emitting polymers (LEP), involve an electroluminescent conductive polymer that
emits light when connected to an external voltage. They are used as a thin film for fullspectrum colour displays. Polymer OLEDs are quite efficient and require a relatively small
amount of power for the amount of light produced.
Vacuum deposition is not a suitable method for forming thin films of polymers. However,
polymers can be processed in solution, and spin coating is a common method of
depositing thin polymer films. This method is more suited to forming large-area films
than thermal evaporation. No vacuum is required, and the emissive materials can also
be applied on the substrate by a technique derived from
commercial inkjet printing.However, as the application of subsequent layers tends to
dissolve those already present, formation of multilayer structures is difficult with these
methods. The metal cathode may still need to be deposited by thermal evaporation in
vacuum. An alternative method to vacuum deposition is to deposit a Langmuir-Blodgett
film
Typical polymers used in PLED displays include derivatives of poly(p-phenylene
vinylene) and polyfluorene. Substitution of side chains onto the polymer backbone may
determine the colour of emitted light or the stability and solubility of the polymer for
performance and ease of processing. While unsubstituted poly(p-phenylene vinylene)
(PPV) is typically insoluble, a number of PPVs and related poly(naphthalene vinylene)s
(PNVs) that are soluble in organic solvents or water have been prepared via ring
opening metathesis polymerization.
Phosphorescent materials
Ir(mppy)3, a phosphorescent dopant which emits green light.
Phosphorescent organic light emitting diodes use the principle of electrophosphorescence to
convert electrical energy in an OLED into light in a highly efficient manner, with the internal
quantum efficiencies of such devices approaching 100%.Typically, a polymer such as poly(nvinylcarbazole) is used as a host material to which an organometallic complex is added as a
dopant. Iridium complexes[48] such as Ir(mppy)3 are currently the focus of research, although
complexes based on other heavy metals such as platinum have also been used.

17. The heavy metal atom at the centre of these complexes exhibits strong spin-orbit
coupling, facilitating intersystem crossing between singlet and triplet states. By using
these phosphorescent materials, both singlet and triplet excitons will be able to decay
radiatively, hence improving the internal quantum efficiency of the device compared to a
standard PLED where only the singlet states will contribute to emission of light.
Applications of OLEDs in solid state lighting require the achievement of high brightness
with good CIE coordinates (for white emission). The use of macromolecular species like
polyhedral oligomeric silsesquioxanes (POSS) in conjunction with the use of
phosphorescent species such as Ir for printed OLEDs have exhibited brightnesses as
high as 10,000 cd/m2.
OLED Advantages
The LCD is currently the display of choice in small devices and is also popular in largescreen TVs. Regular LEDs often form the digits on digital clocks and other electronic
devices. OLEDs offer many advantages over both LCDs and LEDs, including:
• The plastic, organic layers of an OLED are thinner, lighter and more flexible than the
crystalline layers in an LED or LCD.
• Because the light-emitting layers of an OLED are lighter, the substrate of an OLED
can be flexible instead of rigid. OLED substrates can be plastic rather than the glass
used for LEDs and LCDs.
• OLEDs are brighter than LEDs. Because the organic layers of an OLED are much
thinner than the corresponding inorganic crystal layers of an LED, the conductive and
emissive layers of an OLED can be multi-layered. Also, LEDs and LCDs
require glass for support, and glass absorbs some light. OLEDs do not require glass.
• OLEDs do not require backlighting like LCDs. LCDs work by selectively blocking areas
of the backlight to make the images that you see, while OLEDs generate light
themselves. Because OLEDs do not require backlighting, they consume much less
power than LCDs (most of the LCD power goes to the backlighting). This is especially
important for battery-operated devices such as cell phones.
• OLEDs are easier to produce and can be made to larger sizes. Because OLEDs are
essentially plastics, they can be made into large, thin sheets. It is much more difficult to
grow and lay down so many liquid crystals.
• OLEDs have large fields of view, about 170 degrees. Because LCDs work by blocking
light, they have an inherent viewing obstacle from certain angles. OLEDs produce their
own light, so they have a much wider viewing range.
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 displays. However, fabrication of the OLED substrate is more costly

18. than that of a TFT LCD, until mass production methods lower cost through
scalability. Roll-to-roll vapour-deposition methods for organic devices do allow
mass production of thousands of devices per minute for minimal cost, although
this technique also induces problems in that devices with multiple layers can be
challenging to make because of registration, lining up the different printed layers
to the required degree of accuracy.
Lightweight and flexible plastic substrates
OLED displays can be fabricated on flexible plastic substrates leading to the
possible fabrication of flexible organic light-emitting diodes for other new
applications, such as roll-up displaysembedded in fabrics or clothing. As the
substrate used can be flexible such as polyethylene terephthalate (PET),the
displays may be produced inexpensively.
Wider viewing angles and improved brightness
OLEDs can enable a greater artificial contrast ratio (both dynamic range and
static, measured in purely dark conditions) and a wider viewing angle compared
to LCDs because OLED pixels emit light directly. OLED pixel colors appear
correct and unshifted, even as the viewing angle approaches 90° from normal.
Better power efficiency and thickness
LCDs filter the light emitted from a backlight, allowing a small fraction of light
through. So, they cannot show true black. However, an inactive OLED element
does not produce light or consume power, thus allowing true blacks. Dismissing
the backlight also makes OLEDs lighter because some substrates are not
needed. This allows electronics potentially to be manufactured more cheaply,
but, first, a larger production scale is needed, because OLEDs still somewhat are
niche products.When looking at top-emitting OLEDs, thickness also plays a role
when talking about index match layers (IMLs). Emission intensity is enhanced
when the IML thickness is 1.3–2.5 nm. The refractive value and the matching of
the optical IMLs property, including the device structure parameters, also
enhance the emission intensity at these thicknesses.
Response time
OLEDs also can have a faster response time than standard LCD screens.
Whereas LCD displays are capable of between 1 and 16 ms response
time offering a refresh rate of 60 to 480 Hz, an OLED theoretically can have a
response time less than 0.01 ms, enabling a refresh rate up to 100,000 Hz..
OLEDs also can be run as a flicker display, similar to a CRT, in order to eliminate
the sample-and-hold effect that creates motion blur on OLEDs
OLED Disadvsantages
OLED seem to be the perfect technology for all types of displays,

19. however, they do have some problems, including:
OLED manufacture currently requires process steps that make it extremely expensive.
Specifically, it requires the use of low-temperature polysilicon backplanes; LTPS
backplanes, in turn, require laser annealing from an amorphous silicon start, so this part
of the manufacturing process for AMOLEDs starts with the process costs of standard
LCD, and then adds an expensive, time-consuming process that cannot currently be
used on large-area glass substrates.
Lifespan
The biggest technical problem for OLEDs was the limited lifetime of the organic
materials. One 2008 technical report on an OLED TV panel found that "After
1,000 hours the blue luminance degraded by 12%, the red by 7% and the green
by 8%."
In particular, blue OLEDs historically have had a lifetime of around 14,000 hours
to half original brightness (five years at 8 hours a day) when used for flat-panel
displays. This is lower than the typical lifetime of LCD, LED or PDP technology.
Each currently is rated for about 25,000–40,000 hours to half brightness,
depending on manufacturer and model.Degradation occurs because of the
accumulation of nonradiative recombination centers and luminescence
quenchers in the emissive zone.
It is said that the chemical breakdown in the semiconductors occurs in four
steps:
1) recombination of charge carriers through the absorption of UV light,
2) hemolytic dissociation,
3)subsequent radical addition reactions that form π radicals, and
4) disproportionation between two radicals resulting in hydrogen-atom transfer
reactions.However, some manufacturers' displays aim to increase the lifespan of
OLED displays, pushing their expected life past that of LCD displays by
improving light outcoupling, thus achieving the same brightness at a lower drive
current.
In 2007, experimental OLEDs were created which can sustain
400 cd/m2 of luminance for over 198,000 hours for green OLEDs and 62,000
hours for blue OLEDs.
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 variation in the
differential color output will change the color balance of the display and is much
more noticeable than a decrease in overall luminance. This can be avoided
partially by adjusting color balance, but this may require advanced control circuits
and interaction with the user, which is unacceptable for some users. More
commonly, though, manufacturers optimize the size of the R, G and B subpixels
to reduce the current density through the sub pixel in order to equalize lifetime at

20. full luminance. For example, a blue subpixel may be 100% larger than the green
subpixel. The red subpixel may be 10% smaller than the green.
Efficiency of blue OLEDs
Improvements to the efficiency and lifetime of blue OLEDs is vital to the success
of OLEDs as replacements for LCD technology. Considerable research has been
invested in developing blue OLEDs with high external quantum efficiency as well
as a deeper blue color. External quantum efficiency values of 20% and 19% have
been reported for red (625 nm) and green (530 nm) diodes, respectively.
However, blue diodes (430 nm) have only been able to achieve maximum external
quantum efficiencies in the range of 4% to 6%.
OLED market reports News:
Flexible and Curved Display Technologies and Market Forecast Report
Company: Touch Display Research
Report publishing date: 10/2013
Press Release––Flexible and curved displays will account for 16% of market by 2023
Santa Clara, October 1, 2013—Touch Display Research announces the publication of
―Flexible and Curved Display Technologies and Market Forecast Report.‖ This report
profiles over 260 companies and research institutes working on flexible and curved
displays. Touch Display Research forecasts that the flexible and curved display market
will grow from less than 1% market share in 2013 to $27 Billion and 16% market share
of global display revenue by 2023.
Figure. Flexible and curved display market forecast to 2023

21. OLED Displays Market - Global Industry Analysis, Market Size, Share, Growth And
Forecast, 2012 - 2018
Company: Transparency Market Research
Report publishing date: 01/2013
The research report on the OLED displays market is analyzed based on major
applications such as mobile phones, TV, notebooks, tablets, digital cameras, and
automotives. The global OLED displays market is expected to reach $25.9 billion by
2018 from $4.9 billion in 2012 growing at a CAGR of 31.7% from 2012 to 2018. Mobile
phones are the largest end use application and accounted for 71% of the total OLED
displays market in 2012, but the share of OLED TV displays are expected to surpass
the shares of mobile phone displays by 2015
.
OLED Lighting Market Forecast Q2 2012
Company: Nanomarkets
Report publishing date: 03/2012
This report provides NanoMarkets' market forecasts for OLED lighting. It includes the
revenue potential for the OLED lighting applications that currently interest the OLED
market the most (luxury consumer lighting, decorative lighting for large buildings and
showrooms, office lighting, residential lighting and automotive lighting). It also includes a
detailed analysis of pricing trends in OLED lighting, including the likely roadmaps for
pricing by unit, luminance and square meter.
OLED Displays and Lighting Market to 2020
Company: GBI Research
Report publishing date: 10/2011
This OLED lighting and displays market report gives an in-depth analysis of the global
OLED market for displays and lighting, covering four major regions – North America
(USA and Canada), Europe, Asia–Pacific.
The report covers market revenue forecasts for the OLED market (displays and lighting)
from 2005-2020, and it also provides market revenues breakdown for displays by
application types: mobile phones, TV, IT monitors and others, and technology type;
PMOLED and AMOLED.

22. LG Electronics expects the OLED TV market to gradually replace the LED TV
market
LG Electronics reported their financial results for Q4 2013 and the Korean company
doubled its operating profits compared to last year. LG reports a good quarter in its TV
business, but the mobile unit reported a loss (partly blamed on marketing spending)
even though they sold 13.2 million phones which is 50% higher than in Q3 2012.
Regarding OLEDs, LG says that they expect the OLED TV market to pick up from 2014,
"gradually becoming the main growth driver of the display business and replacing the
LED TV market". The company plans to extend the distribution network and to
strengthen regionally differentiated marketing activities in order to increase sales of
OLED TVs in 2014.
Samsung sold over 10 million Galaxy Note phones in South Korea
Samsung announced that they shipped over 10 million Galaxy Note smartphones in
South Korea alone since launching the original Galaxy Note in 2011. A month ago the
company announced that they shipped over 10 million Note 3 smartphones globally in
little over 2 months, and they also shipped over 38 million Galaxy Noteand Note
2 smartphones globally since launching the original Galaxy Note in 2011.All of
Samsung's Galaxy Note models use large HD Super AMOLED displays. The
original Note had a 5.3" 1280x800 OLED, the Note 2 had a 5.5" OLED display
(1280x720, non-Pentile) and the latest Note 3 sports a 5.7" Full-HD Super
AMOLED display (386 PPI, PenTile).
LG sold over 13,000 G Flex phones, says excessive force may cause bumps on
the display
According to a report from Korea, LG sold over 13,000 G Flex smartphones in
Korea. LG wants to lead the flexible OLED smartphone market, and is now launching
this phone in the US and in Europe. iSuppli: the OLED TV market is finally beginning,
shipments will reach 10 million in 2018.
Market research firm iSuppli expects the OLED TV market to grow quickly in coming
years. 2014 will still be a slow year with only 50,000 sets sold globally (most of them will
be made by LG), but this will quickly grow to 700,000 in 2015, 2.2 million in 2016 and
5.1 million in 2017.
In 2018, over iSuppli came back from CES with the conclusion that while there are still
challenges, it seems that TV makers are committed to promote OLED technologies.
They expect the technical issues to be overcome and high-volume production will begin
soon.

24. Conclusion:
OLED display revenues will exceed $35B in 2018, up from $11B in 2013.
AMOLED revenues passed PMOLED in 2009. AMOLED is the growth
force for OLED in the future.
Breakthroughs in oxide TFT and a-Si TFT backplanes and in color
patterning are needed for AMOLED to move to larger sizes.
More than 10 new AMOLED fabs or fab updates are expected in the
next three years.
OLED lighting will reach $6.3 billion by 2018.
Diversify OLED lighting for different applications.
Higher efficiency, longer lifetime, and high priced types are needed as
well as lower efficiency, shorter lifetime and lower priced types.
OLED lighting costs need to be reduced, and efficiency needs to be
improved for mass adoption.
OLED can be combined with other hot technologies: touch screens,
e-paper displays, and 3D.
OLED works in niche applications where LCD cannot compete:
flexible displays
transparent displays lighting.

25. Refrences
http://www.oled-info.com/
http://en.wikipedia.org/wiki/OLED
http://news.oled-display.net/
http://www.engpaper.com/
http://www.gsmarena.com/lg_flexible_oled_smartphone_display_
enters_mass_production-news-6921.php
http://www.raystar-optronics.com/
http://electronics.howstuffworks.com/oled1.htm