Performance Analysis of Luminescent Materials for OLED Applications
1. Presentation On
SEMINAr-1 (2ND Semester)
Amity School of Engineering and Technology
Amity University Uttar Pradesh
Lucknow
“PERFORMANCEANALYSISOF LUMINESCENT MATERIALS FOR OLED
APPLICATIONS: a REVIEW”
Guide: Submitted By:
Prof.(Dr.) Ashok Kumar Mishra Adrija Chowdhury
M.Tech (OEOC)
A7636913003
26 May 2014 1
2. Oled: what is it???
Small LED displays showing only the numeric contains.
Heavy jumbo CRTs: heavy & bulky requiring quiet larger area than
anything else; couldn’t be carried from one place to another.
Compact LCDs: very lighter in weight; easily carried; drawback of
getting the perfect result in some particular direction.
Lightweight, efficient and flexible display technology, based on
OLEDs emerged:
Solid-state semiconductor device
100 to 500 nm thick; 200 times smaller than a human hair.
Consists of a luminescent organic semiconducting layer sandwiched
between two electrodes and deposited on a substrate.
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3. Oled generalized structure
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Substrate (clear plastic, glass, foil):
supports the OLED.
Anode (usually ITO): Transparent to
visible light
Cathode: metals like barium, calcium
and aluminium are used as a cathode
Organic layers: made of organic
molecules or polymers. They are of two
types:
Conducting layer - transport "holes"
from the anode. E.g: polyaniline.
Emissive layer - transport electrons
from the cathode; emits light in response
to an electric current. E.g: polyfluorene.
4. Working mechanism
The battery or power supply of
the device containing the OLED
applies a voltage across the OLED.
An electrical current flows from
the cathode to the anode through
the organic layers. (an electrical
current is a flow of electrons)
At the boundary between the
emissive and the conductive layers,
electrons find electron holes.
The OLED emits light.
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5. PERFORMANCE ANALYSIS OF LUMINESCENT
MATERIALS
Based upon the type of Organic Semiconductor
material used: SM-OLED v/s P-OLED
Based upon the type of electroluminescence
property: Fluorescence v/s Phosphorescence
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10. Characteristics curves analysis ofsm-oled andp-oled
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SM-OLED is better than P-OLED: in terms Of Efficiency and Lifespan; though Costlier
11. fLuorescence v/s phosphorescence
Faster decay
Durable for lesser time
period
Lesser efficient
No spin change of excitons
Emission occurs due to
singlet state excitons only
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Slower decay
Durable for longer time
period
Most efficient
Involves spin change
Both singlet and triplet
state excitons are
responsible for emission
15. Passive matrixoled
Perpendicular cathode/anode
strip orientation
Light emitted at intersection
(pixels)
External circuitry
•Turns on/off pixels
External circuitry
Large power consumption
•Used on 1-3 inch screens
•Alphanumeric display
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16. active matrix oled
Full layers of cathode,
anode, organic molecules
Thin Film Transistor
matrix (TFT) on top of anode
•Internal circuitry to
determine which pixels to
turn on/off
Less power consumed then
PMOLED
•Used for larger displays
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17. transparent oled
Transparent substrate,
cathode and anode
Bi-direction light emission
Passive or Active Matrix
OLED
Useful for heads-up display
•Transparent projector
•Screen
•glasses
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18. Top emitting oled
Non-transparent or
reflective substrate
Transparent Cathode
Used with Active Matrix
Device
Smart card displays
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19. foldable oled
Flexible metallic foil or
plastic substrate
Lightweight and durable
Reduce display breaking
Clothing OLED
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20. white oled
Emits bright white
light
Replace fluorescent
lights
Reduce energy cost for
lighting
True Color Qualities
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21. Fabricationtechnologies
Polymer-based OLEDs: excellent film forming properties; ease of
application over large surfaces through simple, economically viable
coating techniques. e.g-ink jet printing. Small molecule materials:
typically coated as thin films via vacuum-deposition which is
difficult over large areas and is not as cost effective.
The techniques are as follows:
Vacuum deposition or vacuum thermal evaporation (VTE)
Organic vapor phase deposition (OVPD)
Inkjet printing
Transfer-printing
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22. Pros and cons
Much faster response
Consume significantly
less power
Wider viewing angles
Thinner display
Better contrast ratio
Safer for the environment
Light weight
Cost efficient
Brighter
Lifetime: usage gets
limited due to
degradation of materials
Expensive manufacturing
technologies
Susceptible to water
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24. Current trend and conclusion
Manufacturers focusing on finding a cheap way to
produce: “Roll-to-Roll Manufacturing”
Increasing efficiency by: implementing multilayered
structure; boosting lifespan
OLED will replace current LED and LCD technologies
based market
Flexibility and thinness will enable many applications:
may lead to future application: heads-up displays,
automotive dashboards, billboard type displays, home and
office lightings and flexible displays
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