polytronics document

1. CONTENT
1. ABSTRACT
2. INTRODUCTION
3. WHAT IS A POLYMER?
4. HOW DOES POLYMER CONDUCT?
5. APPLICATIONS AND RECENT TRENDS.
6. FLEXONICS
7. THIN FILM TRANSISTORS AND FLAT PANEL
DISPLAY
8. ORGANIC LED’S
9. OTHER POTENTIAL APPLICATIONS
10. CONCLUSION
11. BIBLIOGRAPHY

2. ABSTRACT
“Existence of every thing is felt with new innovations and inventions”. Thus to
replace silicon a alternate technology to meet our present day needs so that the production cost
could reduce to handsome amount, consume less power and overall make thing easy is this
technology “POLYTRONICS”.
POLYTRONICS is an emerging advancement in the materialistic world which
has enormous applications to change the existing conditions to a dramatic extent. The researches
brought about innovative ideas on integrate plastics into mainstream electronics. Viewing of
world could change through flat panel displays. Transistor could be made just like ink-jet
printing on papers. Batteries could be made using plastics. Very soon we could see e-papers
which could be continuously updated via the internet. The age of polymer electronics has begun
and could revolutionize this world.

3. INTRODUCTION
Silicon considered as the best semiconductor and known to be “kith and kin “ of
electronics has largely influenced the electronic industry and would continue to do so over a
period of time. However we are looking for a replacement or an alternative that could meet our
needs. We know pretty well the proverb “Necessity is the mother of invention”; exactly the same
is this case too.
Today most of the electronic circuits are integrated circuits/semiconductor chips
fabricated out of silicon. Producing these circuits involves huge investments known to be in
millions of dollars. So we are coming out with a new technology known as POLYTRONICS
which would be able to produce these circuits on plastics which are flexible enough to be easily
rolled up have display screens that can be continuously updated with sharp images consume less
power and above all can be manufactured at a fraction of the cost involved in making
semiconductor chips.
Thus Polymer Electronics abbreviated as POLYTRONICS is a combination of
two different terminologies meaning electronics using polymers or simply plastics.
Here’s a look into how plastics could revolutionize the world of electronics, what
changes on existing things it could make, what new things it could bring about in detail in our
paper.

4. What is a POLYMER?
Polymers are nothing but macromolecules built by repeated chain of monomers
by the process of polymerization. These polymers are formed because of double and triple bonds
between monomer to form a rigid structure and unique chemical and physical characteristics.
There are many such polymers like polyethylene (polethene), polyactelyene, polyvinylchloride
(PVC) and so on.
In case of polyactelyene, which possesses conjugated double bonds is as shown
in fig.
Based on their ultimate form and use a polymer can be classified as plastics,
elastomer, fibre or resin. When a polymer is shaped into hard and tough utility they are termed as
plastics. As we know polymers or simply plastics are the extensively used in this materialistic
world. Their uses and applications range right from your tooth brush till your clothing and
containers. They are used to coat metal wires to prevent electric shocks. Such is the usage of
polymers in this day today life.

5. HOW DOES A POLYMER CONDUCT?
Simply Ohms Law can define conductivity V= IR. Thus from this relationship
conductivity is found. The conductivity depends on the number of charge carriers (number of
electrons) in the material and their mobility. For example in a metal it is assumed that all the
outer electrons are free to carry charge and the impedance to flow of charge is mainly due to the
electrons "bumping" in to each other. Thus for metals as temperature is increased the resistance
in the material increases as the electrons bump in to each other more as they are moving faster.
Insulators however have tightly bound electrons so that nearly no electron flow
occurs so they offer high resistance to charge flow. So for conductance free electrons are needed.
The diagram below shows how the conductivity of conjugated polymers like polyactelyene can
vary from being an insulator to a conductor.
We think of Polymers as good insulators. However it is now recognized that there
are some polymers which have typical conducting and light emitting properties. The chemical
composition of these polymers is changed by doping (adding impurities) to make them
conducting. Pentacene, oligothiopenes, polyacetelyene,etc,. are found to the best examples.

6. It is well known that graphite is a good conductor, previously it was thought that
polymers which substitute a carbon (e.g. adding hydrogen's to make hydrocarbons) for another
atom could not conduct, however our greater knowledge of conjugated systems has enabled the
discovery of conducting polymers. As in a conjugated system the electrons are only loosely
bound, electron flow may be possible. However as the polymers are covalently bonded the
material needs to be doped for electron flow to occur. Doping is either the addition of electrons
(reduction reaction) or the removal of electrons (oxidation reaction) from the polymer. Once
doping has occurred, the electrons in the pi-bonds are able to "jump" around the polymer chain.
As the electrons are moving along the molecule a electric current occurs.
However the conductivity of the material is limited, as the electrons have to "jump"
across molecules so for better conductivity the molecules must be well ordered and closely
packed to limit the distance "jumped" by the electrons. By doping, the conductivity increases
from 10-3
S m-1
to 3000 S m-1
.This is seen very well in trans undoped polyacetelyene An
oxidation doping (removal of electrons) can be done using iodine. The iodine attracts an electron
from the polymer from one of the pi bonds. Thus the remaining electron can move along the
chain.

7. APPLICATIONS &RECENT TRENDS
As we know the area of applications and usages of polymers are wide spread in
electronics. Most importantly the replacement of silica to fabricate a microchip could bring about
dramatic changes as because the cost will reduce to hand some amount and production too
becomes easier.
Conducting polymers have many uses. The most documented are as follows:
• Corrosion Inhibitors
• Compact Capacitors
• Anti Static Coating
• Electromagnetic shielding for computers
A second generation of conducting polymers have been developed these have
industrial uses like,
• The recent development allows thin-film transistors and even microchips to be made
entirely of organic conductors.
• Display Technology to develop light-emitting polymers for use in the flat panel
displays.
• Light Emitting Diodes (POLY LED’s)
• An inkjet-like technique for producing plastic transistors.
• Solar cells.

8. FLEXONICS
Although current silicon chip technology has had a huge impact on western
lifestyles and the performance of chips is continually being improved, the silicon electronics
industry is an industry facing limitations. Current methods of silicon chip production are very
capital intensive, requiring huge plants and large numbers of chips produced at any one time to
give small returns on large investments. In addition, the turnaround times are lengthy and
mistakes are hugely expensive. Furthermore, supply and demand are far from stable and the
process of producing chips is energy intensive, requires high temperatures and vacuum
processing, and in the case of photolithographic methods, a lot of pure water. There is, however,
a process that promises cheap circuits, tailor made for individual applications produced locally as
they are needed.
Fabrication of microelectronic components plastic substrate instead of silicon
would allow manufacturing of complete gadgets through just printing process in the near future.
This technology would focus on building any electronic device from bottom up gradually, so
instead of building a device by adding new components through the regular ‘assemble and
build’ technique, the entire product would come out of the printer complete with electronic
circuitry embedded in the product. The technology of producing such embedded electronic
circuitry of plastic wafers is “FLEXONICS”.
The principles that apply to printing on polymer are similar to those used in
industrial ink jet printing. Although plastic semiconductors are not yet kings of performance
(plastic inhibits electron mobility), the technology could drastically reduce production costs,
because it is much less volatile than silicon. It could help usher in low-cost smart appliances. But
it is found a way to print clever materials in such a way that we can make practical.
The new technology will have the most immediate impact on various types of
displays, including mobile-phone screens, flat-screen computer monitors, and televisions. The
inclusion of plastic chips could mean that manufacturers of TFT (thin-film transistor) flat-panel
screens and televisions, which currently use a traditional silicon-based transistor for each pixel,

9. would be able to switch to much cheaper chips. The manufacturing process is simpler, because it
doesn’t require vacuum processing or high temperatures. So facilities will cost a fraction of that
price.
The huge cost of mass-manufacturing silicon microchips is due largely to the
complex processes involved. Photolithographic techniques are used to pattern wafers with micro
circuitry, which is grown in powerful vacuums while the wafers are baked at temperatures of
several hundred degrees Celsius. Silicon foundries typically use wafers of only one size, each
fabricated as a discrete unit in facilities that cost billions of dollars to design and build. There
could be a continuous production line of plastic circuits printed on a plastic substrate and then
cut into individual units. The substrate may perhaps be made of the same acetate material as
transparent Vugraph sheets.
The whole thing works at ambient pressure, doing away with many of the costly
vacuum steps needed for silicon. The printing of circuits on a scale far larger than is possible
with silicon is also in view and of great importance for the development of large flat-screen
displays. The Plastic Logic printer resembles any home office inkjet printer. A piezoelectric
material expands when a voltage is passed across it, pressing on a reservoir of fluid and sending
droplets flying out onto the substrate.
The water-based droplets contain an organic conductor--poly (3,4-
ethylenedioxythiophene) doped with solution of polystyrene sulfonic acid, otherwise known as
PEDOT/PSS. As the droplets dry, they become a conducting layer and form the source and drain
of a transistor. These are then coated with a layer of a semi-conducting polymer (9,9-
dioctylfluorene-co-bithiophene), followed by a dielectric layer of polyvinyl phenol. Finally, the
gate is printed, creating a so-called top gate transistor.
The net result is plastic circuits whose advantages over their silicon counterparts include
low capital investment, a large area capability, the ability to be printed on flexible substrates, an
environmentally friendly production process, transparency, ease of customisation, quick cycle
and turnaround times, robustness, light weight, and thinness.

10. The molecular chains must line up in a way that makes it easy for electrons to hop from
one chain to another. But polymers tend to form into disordered microstructures that reduce
electron-charge--the blight of earlier attempts to produce organic transistors efficiently.
However it is discovered that a careful choice of polymers would yield self-organized
chains that achieved charge mobilities of up to 0.1 cm2
/V/s. All of a sudden, thin film transistors
could match at least some of the properties of their silicon cousins.
We have also had to overcome some inkjet printing limitations, notably a maximum
resolution of around 600 dots per square inch (90/cm2
) arising from natural variations in the
droplets' flight paths. This translates into a feature size of around 50 µm. Now the smaller the
transistor, the shorter the distances electrons must travel within it, and the faster the device can
be switched on and off. Unfortunately, this 50-µm limit falls short of the 10-µm sizes needed for
fast circuits.
So the resolution has to be increased. For now, they do it photo lithographically by
coating the glass substrate with a hydrophobic film of polyimide in a pattern that defines
transistor dimensions. When the water-based droplets fall on the surface, they are forced away
from the hydrophobic regions in the required pattern. So far, single transistors and simple logic
circuits have been produced with a feature length of as little as 5 µm. This should lead to circuits
with the switching speeds of a few tens of kilohertz needed for display applications and smart
tags.
It is believed that photolithography can be replaced by other techniques, such as photo
patterning, in which having ultraviolet light shone on it patterns a single hydrophilic layer. Thus
the circuit could still be fabricated in successive steps of coating and printing. Using
photolithography now is an obvious shortcoming of initial demonstrations, but it won’t be a
problem in the long term. To overcome this problem via a process of substrate surface energy
patterning, this directs the flow of the water-based conducting polymer inkjet droplets.
More difficult will be making devices of greater complexity. Making a single transistor
is in some sense trivial. Scaling up the technology is the difficult thing. It is planned to build a
more complex prototype chip.

11. THIN FILM TRANSISTORS & FLAT PANEL DISPLAY
The technology developed here enables the formation of a range of devices
required in complex integrated circuits. A patented technology that allows manufacturers to print
plastic onto a polymer substrate. The result is a plastic-based transistor that is inexpensive and
flexible. Particular expertise has been developed in the creation of thin film transistors (TFTs),
the key component of digital circuits. Techniques have also been created to enable the
construction of other circuit elements including interconnects, resistors, capacitors, diodes and
via-holes.
Thin Film Transistor acts as a switch that can be controlled by the voltage put on
the three contacts. These three contacts are called the source, drain and the gate. The transistor
consists of four layers. The thickness of each of the layers is less than 100 nm:
1. The first conducting, layer defines the gate contact .
2. The second insulating, layer electrically separates the gate from the source-
drain layer.
3. The latter is the third conducting, layer.
4.On top this the semi-conducting layer is applied.
How a TFT works :
Changing the gate voltage will vary the conduction in the semi-conducting
layer. At negative gate voltages, positive charges present in the semi-conductor will accumulate
at the semi-conductor insulator interface. When in this case a voltage is applied at the drain
contact (the source is connected to earth) a current will flow from the source to the drain
electrode. The switch is on.

12. Removing the gate voltage, or applying a positive gate voltage, will remove the
positive charges from the interface (depletion), and no current will flow. The switch is off. The
difference in current between the on and off state (the on/off ratio) is about 106.
The step is to inkjet print the transistor source and drain onto the energy
patterned substrate. The water-based conductive polymer used, for example PEDOT, is attracted
to the hydrophilic surface, but repelled by the hydrophobic areas. This stops the conductive
polymer spreading or splashing on the substrate and gives rise to the very high resolution
achievable. The transistor semiconductor, for instance Dow Chemical’s F8T2, is then ink jetted
into the gap before the transistor gate dielectric layer is spin coated from solution across the
entire area. Metal is then deposited to form TFT gates and gate interconnects. The backplane is
now complete and ready for integration with a display effect, such as liquid crystal or e-paper.
Devices are designed by way of CAD software and created using advanced
solution-based processing techniques. The materials used are sophisticated semi conducting,
insulating, and conducting polymers. Additionally, nano-particle metals are utilized. Plastic
electronics replicate many of the electrical functionalities of conventional silicon without
complex vacuum deposition, mask-alignment and high temperature manufacturing processes.
The technology enables production of devices with consistent performance and significant cost
advantages. One of the challenges in developing a manufacturing process that could change an
entire industry is where to concentrate the technology first. It has decided to initially turn to flat
panel displays (FPD), and has done so for a couple of reason. Firstly, technology can be used to

13. manufacture active matrix backplanes and is compatible with glass and flexible substrates, as
well as large area applications. Secondly, the technology can be tested and refined, with a ready
market to hand when perfected. New display effects, in particular bistable displays for electronic
paper applications are being pioneered.
The displays produced are, for the moment, constructed on substrates of glass.
Glass is used as it is easy to handle and its properties are well known and understood. The
substrates are purchased pre-patterned with indium oxide doped with tin oxide, meaning the data
lines and pixels are already positioned. The plastic electronic thin film transistor (TFT) source,
drain and channel are then defined by surface energy patterning. The substrate is hydrophobic
(water hating), but the applied energy patterning is hydrophilic (water loving) so the technique of
energy patterning enables very high resolution to be achieved with channel length.

14. ORGANIC LED’S
Due emergence of the present technology we have developed families of highly
efficient OLED materials. These materials emit light through the process of electro
phosphorescence. In traditional OLEDs, the light emission is based on fluorescence, a transition
from a singlet excited state of a material. According to theoretical and experimental estimation,
the upper limit of efficiency of an OLED doped with fluorescent material, is approximately 25%.
With our electro phosphorescent materials used as a dopant, which exploits both
singlet and triplet excited states; this upper limit is virtually eliminated. Equipped with the
potential of 100% efficiency, the commercialization of electro phosphorescent devices by
optimizing the device efficiency, color purity and device storage and operation durabilities.
Such a process is facilitated by the development and modification of charge
transport materials, charge blocking materials and luminescent materials, and their incorporation
into devices.
TRANSPARENT ORGANIC LED’S:
The Transparent OLED (TOLED) uses a proprietary transparent contact to create
displays that can be made to be top-only emitting, bottom-only emitting, or both top and bottom

15. emitting (transparent). TOLEDs can greatly improve contrast, making it much easier to view
displays in bright sunlight. Because TOLEDs are 70% transparent when turned off, they may be
integrated into car windshields, architectural windows, and eyewear. Their transparency enables
TOLEDs to be used with metal, foils, silicon wafers and other opaque substrates for top-emitting
devices.
TOLED Creates New Display Opportunities:
• Directed top emission: Because TOLEDs have a transparent structure, they may be built
on opaque surfaces to effect top emission. Simple TOLED displays have the potential to
be directly integrated with future dynamic credit cards. TOLED displays may also be
built on metal, e.g., automotive components. Top emitting TOLEDs also provide an
excellent way to achieve better fill factor and characteristics in high resolution, high-
information-content displays using active matrix silicon backplanes.
• Transparency: TOLED displays can be nearly as clear as the glass or substrate they're
built on. This feature paves the way for TOLEDs to be built into applications that rely on
maintaining vision area. Today, "smart" windows are penetrating the multi-billion dollar
flat glass architectural and automotive marketplaces. Before long, TOLEDs may be
fabricated on windows for home entertainment and teleconferencing purposes; on and
into helmet-mounted or "head-up" systems for virtual reality applications.
• Enhanced high-ambient contrast: TOLED technology offers enhanced contrast
ratio. By using a low-reflectance absorber (a black backing) behind either top or bottom TOLED
surface, contrast ratio can be significantly improved over that in most reflective LCDs and

16. OLEDs. This feature is particularly important in daylight readable applications, such as on cell
phones and in military fighter aircraft cockpits.
• Multi-stacked devices: TOLEDs are a fundamental building block for many multi-
structure (i.e. SOLEDs) and hybrid devices. Bi-directional TOLEDs can provide two
independent displays emitting from opposite faces of the display. With portable products
shrinking and desired information content expanding, TOLEDs make it possible to get twice the
display area for the same display size.
STACKED OLED’S:
A SOLED display consists of an array of vertically stacked TOLED sub-
pixels. To separately tune color and brightness, each of the red, green and blue (R-G-B) sub-
pixel elements is individually controlled. By adjusting the ratio of currents in the three elements,
color is tuned. By varying the total current through the stack, brightness is varied. By modulating
the pulse width, gray scale is achieved. With this SOLED architecture, each pixel can, in
principle, provide full color. Universal Display Corporation's SOLED technology may be the
first demonstration of an vertically-integrated structure where intensity, color and gray scale can
be independently tuned to achieve high-resolution full-color.
PERFORMANCE ENHANCEMENT:
The SOLED architecture is a significant departure from the traditional side-by-
side (SxS) approach used in CRTs and LCDs today. Compared to SxS configurations, SOLEDs
offer compelling performance enhancements:
• Full-color tunability: SOLEDs offer dynamic full-color tunability for "true" color
quality at each pixel valuable when color fidelity is important.
• High resolution: SOLEDs also offer 3X higher resolution than the comparable SxS
display. While it takes three SxS pixels (an R, G and B) to generate full-color, it takes
only one SOLED pixel or one-third the area to achieve the same. This is especially
advantageous when maximizing pixel density is important.

17. • Nearly 100% fill factor: SOLEDs also maximize fill factor. For example, when a full-
color display calls for green, the red and blue pixels are turned off in the SxS structure.
By comparison, all the pixels turn on green in a SOLED under the same conditions. This
means that SOLED color definition and picture quality are superior.
• Scalable to large pixel size: In large screen displays, individual pixels are frequently
large enough to be seen by the eye at short range. With the SxS format, the eye may
perceive the individual red, green and blue instead of the intended color mixture. With a
SOLED, each pixel emits the desired color and, thus, is perceived correctly no matter
what size it is and from where it is viewed.
FLEXIBLE OLED’S:
FOLEDs are organic light emitting devices built on flexible substrates. Flat panel
displays have traditionally been fabricated on glass substrates because of structural and/or
processing constraints. Flexible materials have significant performance advantages over
traditional glass substrates.
FOLEDs Offer Revolutionary Features for Displays:
• Flexibility: For the first time, FOLEDs may be made on a wide variety of substrates that
range from optically-clear plastic films to reflective metal foils. These materials provide
the ability to conform, bend or roll a display into any shape. This means that a FOLED
display may be laminated onto a helmet face shield, an aircraft cockpit instrument panel
or an automotive windshield.
• Ultra-lightweight, thin form: The use of thin plastic substrates will also significantly
reduce the weight of flat panel displays in cell phones, portable computers and,
especially, large-area televisions-on-the-wall. For example, the weight of a display in a
laptop may be significantly reduced by using FOLED technology.
• Durability: FOLEDs will also generally be less breakable, more impact resistant and
more durable compared to their glass-based counterpart.
• Cost-effective processing: OLEDs are projected to have full-production level cost
advantage over most flat panel displays. With the advent of FOLED technology, the

18. prospect of roll-to-roll processing is created. To this end, our research partners have
demonstrated a continuous organic vapor phase deposition (OVPD) process for large-area
roll-to-roll OLED processing.
How PASSIVE MATRIX works:
Passive Matrix displays consist of an array of picture elements, or pixels,
deposited on a patterned substrate in a matrix of rows and columns. In an OLED display, each
pixel is an organic light emitting diode, formed at the intersection of each column and row line.
The first OLED displays, like the first LCD (Liquid Crystal Displays), are addressed as a passive
matrix. This means that to illuminate any particular pixel, electrical signals are applied to the
row line and column line. The more current pumped through each pixel diode, the brighter the
pixel looks to our eyes.
How ACTIVE MATRIX works:
In an active matrix display, the array is still divided into a series of row and
column lines, with each pixel formed at the intersection of a row and column line. However,
each pixel now consists of an organic light emitting diode (OLED) in series with a thin film
transistor (TFT). The TFT is a switch that can control the amount of current flowing through the
OLED. In an active matrix OLED display (AMOLED), information is sent to the transistor in
each pixel, telling it how bright the pixel should shine. The TFT then stores this information and
continuously controls the current flowing through the OLED. In this way the OLED is operating
all the time, avoiding the need for the very high currents necessary in a passive matrix display.
Our new high efficiency material systems are ideally suited for use in active matrix OLED
displays, and their high efficiencies should result in greatly reduced power consumption. The
TOLED architecture enables the organic diode, which is placed in each pixel to emit its light
upwards away from the substrate. This means that the diode can be placed over the TFT
backplane, resulting in a brighter display.

19. OTHER POTENTIAL APPLICATIONS OF
POLYTRONICS
As well as displays, there is enormous potential for plastic electronics in relatively
simple logic applications, once the technology takes hold. Using the same process that produces
electronic backplanes for displays, entry into markets such as electronic barcodes (RFID tags)
and intelligent packaging, currently a US$2billion market, are distinctly probable. It is a boost to
this emerging market recently by ordering 500 million silicon-based electronic tags for an initial
pilot project. Printed electronics will be a key enabler of intelligent packaging and low-cost
electronic labels.
Beyond this, plastic electronics can add value in many diverse markets, but will only
do so once the technology has matured. In one sense the technology is complementary to
conventional silicon electronics, serving established billion-dollar markets such as electronic
displays and enabling new concepts such as electronic labels, intelligent bio-sensors, disposable
electronics, flexible e-paper and electro-textiles, as well as novelty applications - gadgets,
gizmos and games. It is likely that the biggest applications for plastic electronics are yet to be
discovered. In addition we could see plastic batteries coming out for low power consumption
areas. These could even replace the solar cells the present technology.

20. CONCLUSION
The overall impact of this technology is likely to be huge. This is without doubt a
completely disruptive technology. In the same way that the steel industry moved from integrated
works to smaller facilities requiring lower capital intensity, so ‘our inkjet printing of plastic
circuits will do the same to the electronics industry.’ The age of polymers has begun, where in
the form factor, flexibility and low cost of production would result in constant innovation.
The Future for Plastic Electronics:
The economics of direct writing plastic electronics will ensure that the technology
will not end up centred in those countries that have very cheap labour costs. ‘Mini fabrication
centres will be sited next to the customer, as the initial cost of the process will be much lower by
not requiting masks and big plants’. As for future there could be supply of a complete plastic
electronics package, delivered through a set of standards, operating procedures and licences that
enable direct writing of electronic circuits to take place whenever there is a need or application
for them. When this comes to pass, there really will be chips with everything. Let’s wait for the
clock to turn around to enjoy the beautiful and interesting applications of this technology!.....
BIBLIOGRAPHY:
1.www.polymervision.com
2.www.battcon.com
3.www.polytronics.org
4.www.polytronicseng.com