The document discusses organic light-emitting diodes (OLEDs), detailing their structure, working principles, advantages, and applications. It outlines the manufacturing techniques, materials used, and different classifications of OLEDs, highlighting their potential in modern technology such as displays and wearable electronics. The future of OLED technology looks promising, with prospects for flexible and transparent displays in various applications.

1. ORGANIC LIGHT
EMITTING
DIODE(O.L.E.D.)

2. PRESENTED BY :-
MOHAMMAD HAMMAD AHMAD (2K12/EE/080)
DEPARTMENT OF ELECTRICAL ENGINEERING
DELHI TECHNOLOGICAL UNIVERSITY , NEW DELHI-110042

3. WHAT IS A
L.E.D. ?
L.E.D. OR LIGHT EMITTING DIODE IS A SEMICONDUCTOR LIGHT
SOURCE THAT WORKS ON THE PRINCIPLE OF
ELECTROLUMINESCENCE WHICH IS A RESULT OF RADIATIVE
RECOMBINATION OF ELECTRONS AND HOLES IN A MATERIAL.
STRUCTURE AND WORKING

4. LED CONSISTS OF A CHIP OF
SEMICONDUCTING MATERIAL DOPED
WITH IMPURITIES TO CREATE A P-N
JUNCTION. AS IN OTHER DIODES,
CURRENT FLOWS EASILY FROM THE P-
SIDE, OR ANODE, TO THE N-SIDE, OR
CATHODE, BUT NOT IN THE REVERSE
DIRECTION. CHARGE-CARRIERS—
ELECTRONS AND HOLES—FLOW INTO
THE JUNCTION FROM ELECTRODES WITH
DIFFERENT VOLTAGES. WHEN AN
ELECTRON MEETS A HOLE, IT FALLS
INTO A LOWER ENERGY LEVEL AND
RELEASES ENERGY IN THE FORM OF A
PHOTON.

5. ADVANTAGES AND
DISADVANTAGES
ADVANTAGES
1.LEDS CONSUME LESSER POWER AS COMPARED TO NORMAL
INCANDESCENT LIGHTS.
2.LEDS HAVE LONGER LIFETIME.
3.LEDS HAVE LESSER RESPONSE TIME.
4.LEDS RADIATE LESS HEAT.
5.LEDS CAN EMIT LIGHT OF ANY COLOR USING SPECIFIC FILTER.
6.LEDS CAN BE OF VERY SMALL SIZE .
7.AND MANY MORE……

6. 1.LEDs are expensive.
2.LEDs are temperature dependent and their performance
is affected by temperature to a very large extent.
3.LEDs works between certain voltage and current ranges.
4.LEDs works only when they are connected with correct
electrical polarity.
DISADVANTAGES

7. THERE ARE MANY USES OF L.E.D.S IN PRESENT TIME FEW OF WHICH ARE :-
1.VISUAL SIGNALS WHERE LIGHT GOES MORE OR LESS DIRECTLY FROM
THE SOURCE TO THE HUMAN EYE, TO CONVEY A MESSAGE OR
MEANING.
2.ILLUMINATION WHERE LIGHT IS REFLECTED FROM OBJECTS TO GIVE
VISUAL RESPONSE OF THESE OBJECTS.
3.MEASURING AND INTERACTING WITH PROCESSES INVOLVING NO
HUMAN VISION.
4.NARROW BAND LIGHT SENSORS WHERE LEDS OPERATE IN A REVERSE-
BIAS MODE AND RESPOND TO INCIDENT LIGHT, INSTEAD OF EMITTING
LIGHT.
5.EMITTING WIRELESS INTERNET SIGNAL CALLED LI-FI.
6.LEDS CAN ALSO BE USED WITH CONTACT LENSES OR NORMAL EYE
GLASSES MOST RECENT EXAMPLE IS GOOGLE GLASS.
7.THE LIGHT FROM LEDS CAN BE MODULATED VERY QUICKLY SO THEY
ARE USED EXTENSIVELY IN OPTICAL FIBER AND FREE SPACE OPTICS
COMMUNICATIONS.
Applications

8. WHAT IS AN O.L.E.D.
STRUCTURE,MANUFACTURING AND WORKING
An OLED (organic light-emitting diode) is a light-emitting diode (LED) in which the emissive
electroluminescent layer is a film of organic compound which emits light in response to an
electric current.

9. . This layer of organic semiconductor is situated between 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.

10. HISTORY AND
DEVELOPMENT
 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.
 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.
 ALSO IN 1965, W. HELFRICH AND W. G. SCHNEIDER OF THE NATIONAL RESEARCH
COUNCIL IN CANADA PRODUCED DOUBLE INJECTION RECOMBINATION

11. 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 MILLIMETRE THIN LAYERS OF A MELTED PHOSPHOR
CONSISTING OF GROUND ANTHRACENE POWDER, TETRACENE, AND
GRAPHITE POWDER.

12. WORKING PRINCIPLE

13. OLED Components
Like an LED, an OLED is a solid-state semiconductor device that is 100 to 500 nanometers thick
or about 200 times smaller than a human hair. OLEDs can have either two layers or three layers
of organic material,the third layer helps transport electrons from the cathode to the emissive
layer. Thus, the organic material must serve all the three main functions: electron
transport, hole transport and emission. The injection rates of both carriers should be almost
equal for high efficiency. Otherwise, the surplus electrons or holes will not recombine, which
results in low operation efficiency
An OLED consists of the following parts:
1. Substrate (clear plastic, glass, foil) - The substrate supports the OLED.
Anode (transparent) - The anode removes electrons (adds electron "holes") when a current flows
through the device.
2. Organic layers - These layers are made of organic molecules or polymers.
Conducting layer - This layer is made of organic plastic molecules that transport "holes“ from
the anode. One conducting polymer used in OLEDs is polyaniline.

14. 3. 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. One polymer used in the emissive layer is polyfluorene.
4. Cathode (may or may not be transparent depending on the type of OLED) -
The cathode injects electrons when a current flows through the device.

15. The biggest part of manufacturing OLEDs is applying the organic layers to the
substrate. This can be done in three ways:
1. Vacuum deposition or vacuum thermal evaporation (VTE) - In a vacuum
chamber, the organic molecules are gently heated (evaporated) and allowed to
condense as thin films onto cooled substrates. This process is expensive and
inefficient.
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 for large displays like 80-inch TV screens or electronic billboards.
MANUFACTURING TECHNIQUE

16. MATERIALS USED
1.POLYMER(S)
 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 FULL-SPECTRUM COLOUR
DISPLAYS. POLYMER OLEDS ARE QUITE
EFFICIENT AND REQUIRE A RELATIVELY
SMALL AMOUNT OF POWER FOR THE
AMOUNT OF LIGHT PRODUCED.
 TYPICAL POLYMERS USED IN PLED
DISPLAYS INCLUDE DERIVATIVES OF

17. 1.PHOSPHORESCENT MATERIALS
 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(N-VINYLCARBAZOLE) IS
USED AS A HOST MATERIAL TO WHICH AN ORGANOMETALLIC
COMPLEX IS ADDED AS A DOPANT. IRIDIUM COMPLEXES SUCH
AS IR(MPPY)3.
3.FLUOROSCENT
THESE TYPE OF ORGANIC L.E.D.S HAVE FLOUROSCENT
MATERIAL AS THEIR MAIN CONSTITUENT AND THESE TYPE
OF ORGANIC LIGHT EMITTING DIODES ARE THE MOST
WIDELY USED ONES.
EXAMPLE:- PERYLENE

18. 4. SMALL MOLECULE
OLED
 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.
 FLUORESCENT DYES CAN BE CHOSEN TO OBTAIN
LIGHT EMISSION AT DIFFERENT WAVELENGTHS, AND
COMPOUNDS SUCH AS PERYLENE, RUBRENE AND
QUINACRIDONE DERIVATIVES ARE OFTEN USED.

19. ON THE BASIS OF PIXEL CONTROL/DRIVING
METHOD
1. A.M.O.L.E.D.-IN A.M.O.L.E.D. OR ACTIVE MATRIX
ORGANIC LIGHT EMITTING DIODE THE PIXELS ARE
CONTROLLED DIRECTLY.THIS TECHNIQUE IS USED
TO MAKE LARGER AND MORE EFFICIENT DISPLAYS
BUT IS EXPENSIVE.
2. P.M.O.L.E.D.-IN P.M.O.L.E.D. OR PASSIVE MATRIX
ORGANIC LIGHT EMITTING DIODE THE DISPLAY IS
CONTROLLED BY SWITCHING A CERTAIN ROW AND
COLUMN - IN EFFECT LIGHTING THE PIXEL AT THE
INTERSECTION. THE PIXELS ARE TURNED ON AND
OFF QUICKLY, AND THE SEQUENCE CREATES THE
IMAGE. BUT IT ONLY ALLOW FOR SMALL SIZED
DISPLAYS (UP TO 3", TYPICALLY) AND IS CHEAP.
Classification

20. ON BASIS OF DIRECTION LIGHT EXITS O.L.E.D.
1. TOP EMISSION- . TOP EMISSION DEVICES ARE CLASSIFIED BASED ON WHETHER OR
NOT THE LIGHT EMITTED FROM THE OLED DEVICE EXITS THROUGH THE LID THAT IS
ADDED FOLLOWING FABRICATION OF THE DEVICE. TOP-EMITTING OLEDS ARE
BETTER SUITED FOR ACTIVE-MATRIX APPLICATIONS AS THEY CAN BE MORE EASILY
INTEGRATED WITH A NON-TRANSPARENT TRANSISTOR BACKPLANE.
2. BOTTOM EMISSION-. OLED DEVICES ARE CLASSIFIED AS BOTTOM EMISSION DEVICES
IF LIGHT EMITTED PASSES THROUGH THE TRANSPARENT OR SEMI-TRANSPARENT
BOTTOM ELECTRODE AND SUBSTRATE ON WHICH THE PANEL WAS MANUFACTURED.

21. ON BASIS OF MANUFACTURING MATERIAL
1. SMALL MOLECULE-SMALL MOLECULES' OLEDS ARE MORE
COMMON TODAY, WITH MOST DISPLAYS USING THOSE KIND
OF MATERIALS.THIS TYPE OF O.L.E.D. IS DIFFICULT TO
FABRICATE.
2. LARGE MOLECULE/POLYMER BASED-LARGE MOLECULES
(ALSO CALLED POLYMER-BASED OLEDS, OR P-OLEDS) ARE
LAGGING BEHIND IN LIFETIME AND EFFICIENCY SPECS. P-
OLEDS MIGHT BE EASIER TO MAKE, THOUGH, BECAUSE THEY
ARE MORE EASILY ADAPTED FOR PRINTING.
3. FLOURSCENT O.L.E.D.-THESE TYPE OF O.L.E.D.S HAS
FLUORESCENT MATERIAL AS MAJOR CONSTITUENT.THESE
ARE THE MOST USED O.L.E.D.S.
4. PHOSPHORESCENT O.L.E.D.-THESE O.L.E.D.S HAS
PHOSPHORESCENT MATERIAL AS MAJOR CONSTITUENT
.THEY ARE KNOWN TO GIVE A MORE EFFICIENT PICTURE.

22.  SOME OTHER O.L.E.D.
1. FOLDABLE O.L.E.D.S-SUBSTRATE IS MADE OF FLEXIBLE
METALLIC FOILS OR PLASTICS. THEY ARE LIGHTWEIGHT
AND CONSIDERED VERY DURABLE.
2. TRANSPARENT O.L.E.D.S-USE TRANSPARENT OR SEMI-
TRANSPARENT CONTACTS ON BOTH SIDES TO CREATE
DISPLAYS THAT CAN BE TOP AND BOTTOM EMITTING.
OFFERS GREAT CONTRAST.
3. STACKED O.L.E.D.-UNIQUE PIXEL ARCHITECTURE THAT
STACKS RED, GREEN, AND BLUE SUBPIXELS ON TOP OF
ONE ANOTHER (INSTEAD OF NEXT TO EACH ANOTHER).
THIS PROVIDES BETTER COLOR SCOPE AND DEPTH, AND
ALSO REDUCES PIXEL GAP

23. DIFFERENCE BETWEEN LCD,PLASMA
AND OLED DISPLAYS

24. APPLICATIONS
ORGANIC LIGHT EMITTING DIODES HAVE A LOT OF
PRACTICAL APPLICATIONS IN TODAY`S WORLD.SOME OF
WHICH ARE AS FOLLOW…..
THE MOST WIDE USE OF ORGANIC L.E.D.S IS IN THE
FIELD OF DISPLAYS OR MORE PRECISELY VDUS(VISUAL
DISPLAY UNITS) SUCH AS MONITORS , TELEVISIONS ,
MOBILE PHONES ETC. O.L.E.D. SCREENS HAVE A MUCH
GOOD DISPLAY RESOLUTION THAN NORMAL LCD(LIQUID
CRYSTAL DISPLAY) AND ALSO HAVE A LONGER LIFETIME
AS COMPARED TO CRT(CATHODE RAY TUBE) DISPLAYS
OR LCD.
ORGANIC LEDS CAN ALSO BE USED IN THE
CONSTRUCTION OF WEARABLE ELECTRONICS.

25. ADVANTAGES
• SUBSTRATE IS FLEXIBLE, WHICH OFFERS THE POSSIBILITY OF NEW
DISPLAY OPTIONS
• PLASTIC CAN BE USED AS OPPOSED TO GLASS, WHICH IS GOOD BECAUSE
GLASS ABSORBS SOME LIGHT
• SINCE MANUFACTURERS ARE WORKING MOSTLY WITH PLASTICS, OLEDS
TEND TO BE EASIER TO PRODUCE
• WIDER VIEWING RANGE (APPROXIMATELY 170°)
• MUCH BETTER COLOR BALANCE BECAUSE MORE THAN 16 MILLION CAN
BE DISPLAYED.

26. • NO PROBLEM TO OBSERVE FROM A HIGH ANGLE (AROUND 160°), WHICH MEANS
BETTER READABILITY FROM DIFFERENT POSITIONS.
• CLEAR AND BRIGHT IMAGE.
• MORE MECHANICALLY RESISTANT - IDEAL FOR POCKET COMPUTERS AND
MOBILE PHONES.
• FAST RESPONSE.
• LOW ENERGY CONSUMPTION.
• WELL READABLE IN CASE OF DIRECT DAYLIGHT.
• POSSIBILITY TO BEND OR SHAPE THE DEVICES.
• ADDITIONAL SOURCE OF LIGHT IS NOT NEEDED SO THEY ARE THINNER AND
LIGHTER.

27. DISADVANTAGES
DESPITE OF BEING VERY MUCH ADVANTAGEOUS OLEDS ALSO HAVE
SOME DISADVANTAGE WHICH ARE..
• WATER CAN DAMAGE THE DEVICE AND LIMIT FLEXIBILITY
• DISPLAYS CAN BE DAMAGED BY PROLONGED EXPOSURE TO UV LIGHT
• PIXEL BRIGHTNESS FADES OVER TIME AND THE VARIED LIFESPAN OF
THE DYES CAN CAUSE A DISCREPANCY BETWEEN RED, GREEN, AND
BLUE INTENSITY; THIS COULD, IN TURN, LEAD TO SCREEN BURN-IN.
• BLUE OLEDS ARE INEFFICIENT: RED (625 NM) AND GREEN (530 NM)
DIODES HAVE SHOWN EXTERNAL QUANTUM EFFICIENCY VALUES OF
20% AND 19%; BLUE DIODES (430 NM), ON THE OTHER HAND, ARE
MUCH LOWER, WITH A REPORTED MAXIMUM EXTERNAL QUANTUM
VALUE BETWEEN 4% AND 6%

28. FUTURE SCOPE
THE FUTURE OF ORGANIC LIGHT EMITTING
TECHNIQUE IS VERY “BRIGHT” INDEED AS DESPITE OF
PRODUCING A VERY CLEAR AND BRIGHT IMAGE THIS
TECHNIQUE ALSO HAS THE ABILITY OF PRODUCING
FLEXIBLE AS WELL AS TRANSPARENT DISPLAYS WHICH
CAN BE USED IN MANY FUTURE APPLICATIONS.
BEING FLEXIBLE ORGANIC LIGHT EMITTING DIODES
CAN ALSO BE INCORPORATED IN MANUFACTURING
WEARABLE ELECTRONICS ,SUCH AS PEBBLE WATCH.
THIS TECHNIQUE CAN ALSO BE USED TO MAKE MORE
EFFICIENT TOUCHSCREEN DISPLAYS AS IN
SMARTPHONES,
ONE OF THE MOST IMPORTANT USE OF THIS
TECHNIQUE IS IN MANUFACTURE OF TRANSPARENT