6. INTRODUCTION
LEP or PLED or P OLED
Polymer which emits light(EM radiations).
Polymers are chains of smaller molecular components
called MONOMERS.
CDT & UDC are developing LEP display.
7. HISTORY
1977 conducting polymers are discovered.
Alan J. Heeger , Alan G. MacDiarmid got Nobel prize
From this OLED evolved.
In 1990 Friend et al found Electroluminescence in the
conducting polymers.
Birth of “LIGHT EMITTING POLYMERS”!!!!!!!!!!!
Poly phinylene vinylene (PPV) is the first LEP
discovered.
8. About LEP………..
Electroluminescence is the principle behind
the LEP.
LEP comes under the category of
conjugated polymers.
Polymers with metallic and
semiconductor characteristics.
Delocalized pi electrons
Band gap ranges from 2.2 to 2.8 ev
Wave length depends on the band gap of
LEP.
9. Thin film of semiconducting
polymer sandwiched between an
ANODE and CATHODE. Metal Cathode
Polymer
ANODE: ITO(Indium Tin Oxide)
CATHODE: Metals (depends upon
the type of LEP)
Glass Substrate
SUBSTRATE: Glass, clear plastic
(depends upon the type of LEP) Transparent Anode (ITO)
Voltage is applied between anode
and cathode
10. Due to applied voltage
electrons and holes will
migrate to polymer
lattice.
They will combine
together to form excitons
Excitons returns to initial
state by emitting
radiation.
11.
12. MATRIX DISPLAYS
PLED displays consists of matrix of pixels.
Each pixel is a light emitting polymer.
Emit light by turning OFF and ON the pixels.
Primary color pixels are positioned very close to form other
colored pixels
To control each pixel DRIVERS are needed.
DRIVERS are Transistors
• 2 matrix
13. TWO TYPES OF MATRIX DISPLAY SYSTEMS
PASSIVE MATRIX DISPLAYS
ACTIVE MATRIX DISPLAYS
14. PASSIVE MATRIX DISPLAY
Each row and column have its own
drivers.
The organic layer is between strips
of cathode and anode.
Intersection forms the Pixel.
Matrix scan every pixel to switched
on or off as required.
Data signal is send to the pixel
sequentially.
If brightness is to increase, current
through that electrode will be
increased.
15. Passive matrix displays……
Easy to make.
Use more power.
If size of display increases..it
will become difficult.
Each pixel only emits light for a
small length of time.
Flickering is more.
Only for small displays.
16. ACTIVE MATRIX DISPLAYS
Each pixel is addressed by
incorporating a TFT.
Brightness of each pixel is
controlled by TFT.
TFT will hold the current.
Current flow is controlled by
setting TFT drivers.
More efficient than passive
matrix displays.
Can be used in large area
displays.
AMOLEP or AMOLED
18. • Substrate is placed on spinning
STEP 1 plate.
• Plate is spinning at a speed of
few thousand rotation per
STEP 2 minute.
• Robotic arm will pour small
amount of polymer solution to
STEP 3 the substrate.
• After spreading ,it is baked to
STEP 4 evaporate any remaining liquid.
• Extremely fine layer of polymers
having a thickness of about
STEP 5 100nm
19. Ink-jet head, Ink and substrate for printing are
different
Primary colour polymers are jetted to the substrate.
Uniformly spread the substrate.
Mainly used for printing LEP images.
Also used for making large display.
21. FLEXIBLE ORGANIC LEP(FOLEP)
Built on a flexible substrate.
They have the ability to conform, bend or
roll a display into any shape.
They are less fragile and more impact
resistant.
Ultra lightweight & thin form.
22.
23. TRANSPARENT ORGANIC
LEP(TOLEP)
Substrate is transparent.
LEPs sandwiched between 2 transparent layers.
Top and bottom emitting layers.
High resolution.
More than 70% transparent when turned off.
Better efficiency.
Faster response.
24.
25. STACKED ORGANIC LEP(SOLEP)
Array of vertically stacked
TOLEP sub-pixels.
Color is tuned by individually
controlling R-G-B sub pixels
Brightness is adjusted by
adjusting the total current in
the stack.
It will only turn on the desired
color pixel only.
Can be used in large displays
True color quality.
26. Screen Refreshing Rates Higher than LCD
Viewing quality Higher than LCD
Screen size Size is not limited in LEP
display
Viewing angle Glare free up to 170
degree
Power consumption Lesser than LCD
27. ADVANTAGES…..
Require only 3.3v & life time of more than 30,000 hr.
Low power consumption.
Self luminous.
No viewing angle dependence.
Manufacturing cost is less.
Can be scaled to any dimension.
No environmental draw backs.
Simple to use.
Very slim flat panel displays.
28. DISADVANTAGES……
Voltage drops may affect the performance.
Limited market availability.
Aging of LEP
Degradation of luminescence
Light intensity gradually decreases.
Disintegrate due to contact with oxygen.
29. APPLICATIONS……
Multi or full color cell phone displays
Full color high-resolution personal digital
assistants(PDAs)
Lightweight wrist watches
Roll-up daily refreshable electronic newspapers
Automobile light systems without bulbs
33. Have both electrical and optical property
A low cost solution for flat panel display.
Many manufactures are working to introduce a
revolutionary changes in the market.
Hazardless to environment.
Simpler and cheaper
Have some limitations
Till it is the superior technology………for the
future…..