This document provides an overview of light emitting polymers (LEPs), which are a type of thin, lightweight and low-power flat panel display technology. It describes the chemistry and structure of LEPs, how they work, types including flexible and transparent polymers, manufacturing processes like spin coating, advantages over other displays, limitations such as aging, and applications including phones, TVs and electronic paper. LEPs have potential for use in many consumer electronics and displays.

1. LIGHT EMITTING
POLYMER
PRESENTED BY :
SARATH KUMAR K

2. CONTENTS
 Introduction
 What is LEP?
 Chemistry behind LEP
 Structure And Working
 Types of LEPs
 Manufacturing
 Advantages
 Limitations
 Applications
 Conclusions

3. INTRODUCTION
 It’s a rapidly emerging technology for next generation flat panel
displays
 It promises thin , light weight emissive display with low drive
voltage , low power consumption , high contrast , wide viewing
angle and fast switching times
 LEPs are inexpensive and consume much less power than any
other flat panel display
 One interesting application of these displays is electronic paper
that can be rolled up like newspaper

4.  Light emitting polymers are superiors than other displays like
liquid crystal displays (LCDs),vacuum fluorescence displays and
electroluminescence displays.
 The technology uses a light-emitting polymer (LEP) that costs
much less to manufacture and run than CRTs because the active
material used is plastic.

5. WHAT IS LEP?
 LEP is a polymer that emits light when voltage is applied to it.
 The structure comprises a thin film semi conducting polymer
sandwiched between two electrodes namely anode and cathode
 When electrons and holes are injected from the electrodes , the
recombination of theses charge carriers takes place , which leads
to emission of light that escape through glass substrate.

6.  The first polymer LEPs used poly phinylene vinylene(PPV) as the
emitting layer
 The band gap determines the wave length and colour of emitted
light

7. STRUCTURE AND WORKING
 The basic LEP consists of a stack of thin organic polymer layers
sandwiched between a transport anode and a metallic cathode.
 The indium-tin-oxide(ITO)coated glass is coated with a polymer
 On the top of it , there is a metal electrode of Al , LI , Mg or Ag
 These moving holes and electrons combine together to form hole-
electron pairs known as “excitons”

9.  When this energy drop occurs light comes out from the device .
this phenomenon is called electroluminescence
 Indium-tin oxide is typically used for the anode

13. TYPES OF LEPs
 Flexible organic LEPs
 Stacked organic LEPs
 Transparent organic LEPs

14. Flexible organic LEPs
 They are built on flexible substrates instead of glass substrates.
 These materials provide the ability to conform , bend or roll a
display into any shape.
 On helmet face shields , military uniforms , shirtsleeves and
automotive windshields

15. Stacked organic LEPs
 They use pixel architecture and offers high-definition display
resolution and true-colour quality for the next generations display
applications
 Each pixel emits the desired colour and thus is perceived
correctly , no matter what size it is and from where it is viewed

16. Stacked organic light-emitting device

17. Transparent organic LEPs
 They can be top , bottom or both top and bottom emitting
(transparent).
 Bi-directional LEPs will provide two independent displays
emitting from opposite faces of the display
 Transparent LEPs are a great way to double the display area for
the same display size

18. Toled Structure

19. MANUFACTURING
 SPIN COATING PROCESS
 This technique involve spinning a disk , that is glass substrate at a
fixed angular velocity and letting a small amount of polymer
solution to drop on the top of the disk
 The robot pours the plastic over the rotating plate , which in turn ,
evenly spreads the polymer on the plate. This results in an
extremely fine layer of the polymer having a thickness of 100
nanometer.

20. : Spin Coating Process

21.  INK JET PRINTING
 Use of inkjet printing for PLED displays
 Red , green and blue polymer solutions are jetted into well
defined areas with an angle of flight deviation of less than 5
 The film thickness uniformity may have to be better than +
2percentage

23. Printer Based Technique

24. ADVANTAGES
 Require only 3.3 volt and have lifetime of more than 30,000
hours
 Great power efficiency than all other flat panel displays
 No directional or blurring effects
 Can be viewed at any angle
 Glare free view up to 160 degree

25.  Cost much less to manufacture and run than CRTs , because the
active material used is plastic
 Can scale from tiny device millimeters in dimension to definition
device up to 5.1 meter in diameter
 Fast switching speed , 1000 times faster than LCDs

26. LIMITATIONS
 AGING OF LEP
 One of the major barriers to the commercial development of LEP
is its usefull lifetime The light intensity gradually decreases and
some discrete regions become totally dark. This is called aging of
LEP
 The solution was to do the final soldering in a glass jar filled
nitrogen

27.  SPACE CHARGE EFFECT
 The effect of space charge on the voltage-current characteristics
and current-voltage characteristics becomes more pronounced
when the difference in the electron hole mobilities is increased.
This will decrease the luminescence and hence decreases the
efficiency

28. APPLICATIONS
 Multi or full colour cell phone displays
 Full colour high-resolution personal digital assistants
 Heads-up instrumentation for cars
 Lightweight wrist watches
 High definition televisions

29.  Roll-up daily refreshable electronic newspapers
 Automobile light systems without bulbs
 Window/wall/partitions that double as computer screens
 Military uniforms
 Aircraft cockpit instrumentation panel a lot of others

30. PHOTOVOLTAICS
 PHOTOVOLTAICS
 PLED technology can be used in reverse, to convert light into
electricity. Devices which convert light into electricity are called
photovoltaic (PV) devices, and are at the heart of solar cells and
light detectors

31. POLY LED TV
 LEPs TVs are really thin - the Sony XEL-1 for example is just
3mm thick. The new prototypes by Sony are merely 0.3mm thick!

32. TRANSPARENT OLEDS
 While there seem to be zero to few readily available uses of
transparent OLEDs (TOLEDs) in the consumer market today, the
technology exists for wide spread use in the future

33. NEWS AND INFORMATION
 Imagine a day when you are reading a newspaper that is capable
of showing pictures and video, is continuously updating itself
with the latest news via Wi-Fi connection, and is also so thin and
flexible that you can roll it up and put it in your backpack or
briefcase.
 “That day may someday be a reality thanks to OLED technology

34. OLED PASSPORT
 Samsung SDI from Germany have designed the OLED passport
which is claimed to be completely manipulation-proof.
 The OLED display will be able to display both video and text
containing information about the passport holder.

35. ADVANCEMENTS IN THE HOME
 One of the many possibilities is to replace regular walls or
windows with similar sized OLED installations which will “lead
to user-definable window spaces".
 These walls will use transparent OLEDs that will make it possible
to have certain areas opaque while other areas clear, depending on
what the homeowner would like. Additionally, “the wall can be
any color or design that you want.

36. CONCLUSION
 LEPs are promising , low cost solutions for today’s flat panel
displays. Although not commercialized yet, these replace bulky
and heavy CRT displays in the near future. However research is
underway to improve the efficiency and lifetime of the polymer
display

37. Bibliography.
 www. cdtltd.co.uk
 www. research.philips.com
 www. covion.com
 www.ieee.com
 D.Rwdinger, R.Farshchi and V.Subramanian. “Inkjet passive
component and plastic substrate”. 2003 IEEE Device Research
conference digest pp.187-188, 2003
 Josephine B.Lee and Vivek Subramanian. “Ink Jet Passive
devices” 2003 IEEE Device Research conference digest, 2003