Organic light emitting diodes, different types, comparison of them, recent developments and future scope.

1. B N Manoj
10ECE043

2. INTRODUCTION
1)An oled is the light emitting diode in which
electro - luminiscent layer is a thin film of
organic compounds, that emits light in response to
electric current applied
2)It works on the principle of electroluminiscence
3)No backlighting is required

3. STRUCTURE :
1)IT CONSISTS OF A
CATHODE AND ANODE
PLACED ON A
SUBSTRATE
2)EMISSIVE LAYER AND
CONDUCTIVE LAYER ARE
PLACED BETWEEN ANODE
AND CATHODE
3)BOTH THE LAYERS ARE
MADE OF ORGANIC
COMPOUNDS

4. 1) Different colours are
produced due to the
different types of organic
materials used
2) Intensity of the light is
controlled by the electric
voltage applied to the
electrodes

5. WORKING:
1)Electric current is
applied across the
electrodes (2-10v)
2)Current flows from
cathode to anode
3)Electroluminiscence
occurs at emissive
layer

6. MAKING OF OLED
1)Vacuum deposition or vacuum thermal evaporation (VTE):
The vacuum thermal evaporation deposition technique consists
in heating until evaporation of the material to be deposited. The
material vapor finally condenses in form of thin film on the cold
substrate surface and on the vacuum chamber walls
2)Organic vapor phase deposition (OVPD):In a low-pressure,
hot-walled reactor chamber, a carrier gas transports evaporated
organic molecules onto cooled substrates, where they condense
into thin films. Using a carrier gas increases the efficiency and
reduces the cost of making OLEDs
3) Inkjet printing:With inkjet technology, OLEDs are sprayed
onto substrates just like inks are sprayed onto paper during
printing. Inkjet technology greatly reduces the cost of OLED
manufacturing and allows OLEDs to be printed onto very large
films

7. INKJET PRINTING
1) high-resolution,low
cost
2) selectively deposit
many
layers in a display
Simultaneously
3) Surface properties of
the substrate affect the
uniformity of the film
thickness

8. Types of oled
1)Passive-matrix OLED
2)Active-matrix OLED
3)Transparent OLED
4)Top-emitting OLED
5)Foldable OLED
6)White OLED

9. ACTIVE MATRIX OLED:
1)In this type of oled,full layers
of cathode and anode are
presentbetween which organic
material is present
2)Each pixel is addressed
using a thin film transistor
,which is placed over
anode,avoiding external
circuitory
3)When each pixel is put
on/off, other pixels can be
addressed

10. PASSIVE MATRIX OLED
1)In this type of oled,
anode and cathode are
placed perpendicularly,
whose intersection
forms a pixel
2)By using external
circuitory,row or
coloumn of pixels are
addressed
3) State of the pixel
should be the same until
the pixel is addressed
again

11. TOP EMITTING
OLED
1)Top-emitting OLEDs have
a substrate that is either
opaque or reflective.
2)They are best suited to
active-matrix design.

12. TEOLED
 Improved active area and power consumption: Especially
advantageous for high-resolution, active-matrix OLED applications,
top-emitting structures can increase the effective active area of the
display.
 With more effective active area, the power required to achieve a
specific luminance level can also be reduced.
 Use of opaque substrates: By emitting light through the top contact
instead of the bottom contact (and substrate), TOLEDs have expanded
the variety of substrate materials that can be used

13. BOTTOM EMISSION OLED
1) Bottom emission oled
has a substrate which
is transparent.
2) Emission of light is
through the apertures
of the thin film
transistor

14. STACKED OLED
1) Stacked OLED, in which the red,
green,and blue emitters are stacked
on top of each other , instead of being
placed side-by-side like in other
OLEDs, LCDs, and CRTs.
2)As a result, for the same display
area as other OLEDs,stacked OLEDs
have resolutions three times greater.
3)The stacked OLED displays’ pixels
can be scaled very
large and still look normal.

15. TRANSPARENT OLED
1)Transparent OLEDs have only
transparent components
(substrate, cathode and anode)
and, when turned off, are up to
85 percent as transparent as their
substrate.
2)When a transparent OLED
display is turned on, it allows
light to pass in both directions.
3)A transparent OLED display
can be either active- or passive-
matrix. This technology can be
used for heads-up displays

16. FOLDABLE OLED
1) Foldable OLEDs have
substrates made of very
flexible metallic foils or
plastics.
2) 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.
3) Potentially, foldable
OLED displays can be
attached to fabrics to create
"smart" clothing

17. WHITE OLED
1)White OLEDs emit white light
that is brighter, more uniform
and more energy efficient than
that emitted by fluorescent lights.
2)White OLEDs also have the
true-color qualities of
incandescent lighting.
3)Because OLEDs can be made in
large sheets, they can replace
fluorescent lights.

18. ADVANTAGES OF OLED:
1)The plastic, organic layers of an OLED are thinner, lighter and more
flexible than the crystalline layers in an LED or LCD.
2)OLEDs are brighter than LEDs and LCDs. Because LEDs and LCDs
require glass for support, and glass absorbs some light. OLEDs do not
require glass.
3)OLEDs do not require backlighting like LCDs.
4) OLEDs can enable a greater artificial contrast ratio (both dynamic
range and static, measured in purely dark conditions)

19. 5)Wider viewing angle: viewing angle compared to LCDs because OLED
pixels directly emit light. OLED pixel colours appear correct and
unshifted, even as the viewing angle approaches 90° from normal
6) They have the potential to be able to be produced much more cheaply
than conventional LED’s, LCD’s and plasma televisions using processes
derived from ink-jet printing
7) Potential to produce much larger displays compared to LCD and
plasma display technology, i.e. a more scalable production process
8) Potentially very energy efficient
9) They can be deposited on large substrates enabling large areas to be
illuminated
10) Lighter than Led
11) Can produce a true black and infinite contrast ratios

20.  Fast response time: OLEDs can also have a faster response time than
standard LCD screens. Whereas LCD displays are capable of between 2
and 16 ms response time offering a refresh rate of 60 to 480 Hz, an
OLED can theoretically have less than 0.01 ms response time, enabling
up to 100,000 Hz refresh rate.
 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.

21. DISADVANTAGES:
 Cost of production is still high. An OLED screen costs more than an
LCD screen of similar size. This is more an issue for large screen
HDTVs than for portable devices that have smaller screens.
 OLED screens are difficult to view in bright sunlight as compared to an
LCD screen. This is significant in the case of portable electronic devices
like a Zune HD or iPod Touch.
 Water can easily damage an OLED screen.
 Life span is another technical problem…for blue led’s,it is far less than
lifespan of lcd’s
 UV sensitivity: oled’s are senitive to uv rays …to avoid this ,a protective
filter is used to block uv rays

22. CURRENT
APPLICATIONS:
Currently, OLEDs are used
in small-screen devices such
as cell phones, PDAs and
digital cameras.

23. MAXIMUS OPTIMUS
KEYBOARD :
Each of its keys is
a display which can
dynamically change
to adapt to
the keyboard
layout in use or to
show the function of
the key.
Each key will have
an oled screen on it
to display

24. FUTURE
APPLICATIONS: