A project based report on polytronics field after several test results

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CHAPTER-1
BACKGROUND OF ELECTRONICS
1.1. History of Semiconductors
The major concept of electronics runs around semiconductors. A semiconductor is a
material that has certain unique properties in the way it reacts to electrical current. It is
a material that has much lower resistance to the flow of electrical current in one
direction than in another. The electrical conductivity of a semiconductor is between
that of a good conductor (like copper) and that of an insulator (like rubber). Hence, the
name semi-conductor. A semiconductor is also a material whose electrical
conductivity can be altered (called doping) through variations in temperature, applied
fields, or adding impurities.
While a semiconductor is not an invention and no one invented the semiconductor,
there are many inventions which are semiconductor devices. The discovery of
semiconductor materials allowed for tremendous and important advancements in the
field of electronics. We needed semiconductors for the miniaturization of computers
and computer parts. We needed semiconductors for the manufacturing of electronic
parts like diodes, transistors, and many photovoltaic cells.
Semiconductor materials include the elements silicon and germanium, and the
compounds gallium arsenide, lead sulfide, or indium phosphide. There are many other
semiconductors, even certain plastics can be made semiconducting, allowing for
plastic light-emitting diodes (LEDs) which are flexible, and can be molded to any
desired shape.

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1.2. Disadvantages of Silicon
With the invention of the transistors in the early half of the nineteenth century, the
field of electronics has undergone innumerable changes that have had tremendous
impact on the life of the common man. Be it education, entertainment or healthcare,
there is possibly no field where electronics has not made an impact. The entire
concept of electronics is based on the study of materials called semi-conductors.
Silicon is one such material that is widely used in the manufacture of electronic
circuits. However the use of silicon has various disadvantages that have led
researchers and scientists all over the world to look for other alternatives. Research
has already begun for materials that can successfully replace Silicon and can come out
with better performances.
Figure 1.2.1 Silicon

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CHAPTER-2
INTRODUCTION TO POLYMERS
2.1. 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, PVC and so on.
In case of polyacetylene, which possesses conjugated double bonds is as shown
Figure 2.1.1 Polyacetylene
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.

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2.2. 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.
Figure 2.2.1. Conductionof Polymers
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.

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Figure 2.2.2 Conjugated Polymers
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 are found to the
best examples.
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.

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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.

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CHAPTER-3
INTRODUCTION TO POLYTRONICS
3.1. Polytronics
For long, it was believed plastics were materials with poor conductivity.
However researchers have proved that when plastics are combined with other
substances in proper chemical compositions they can behave as good
conductors of electricity. This has led to the emergence of an all-new field in
which plastics or ‘conjugated polymers’ are exclusively used in the manufacture
of electronic products. This is the field of POLYTRONICS. The use of plastics
not only reduces the cost involved in the manufacture of electronic items, but
also makes them more flexible and portable. Also Polytronics seems to be the
best answer to the growing menace of electronic wastes.
Polymer electronics is shortly defined as “Polytronics”. ‘Poly’ means ‘many’
and ‘mer’ means ‘parts’. Polymer is a macro molecule composed of many
repeated sub-units. In this field conjugated polymers are widely used in the
manufacture of electronic products.

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CHAPTER-4
APPLICATIONS OF POLYTRONICS
4.1. Ink-Jet Printing Technology
Fabrication of microelectronic components would allow manufacture of
complete gadgets through just printing process in the near future. Such a
technology is being developed by the University of California. The 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 itself.
Figure 4.1.1 CircuitPrinting
The structural, mechanical and electronic elements would be indicated using 3D
printing techniques, in three simple steps: using a CAD software tool think of a
design, take the necessary ingredients and insert them inside the printer and
finally print. Technologists point out that for the process to succeed in major

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applications two main criteria have to be fulfilled: “Basically, the material
viscosity must be low enough to allow controlled ejection from the inkjet during
fabrication. Secondly, the material must remain a liquid for a sufficient time
before jetting so as to not clog the printing orifice, yet solidify within a
reasonable time after jetting”. With these two things in place it would be
possible to print almost anything from a combination of polymer and oligomer
solutions, polymer resins, molten solders and nano-particle suspensions.

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4.2. Rubber Electronics
Researchers at the ‘John Hopkins University’ have successfully built rubber
circuits out of several squashed but extendable gold wires. The circuits are
about 20 times thinner than a human hair and have the potential to be stretched
by over half their initial length without loss of electrical conductivity. Stretched
gold wires are manufactured by electroplating gold onto a sheet of silver, later
on the silver is stripped and the wires are encased inside the polymer. The
rubbery circuits would be woven into clothes to monitor the heartbeat of sports
persons or for better functions such as artificial nerves that can bend inside the
body. Such flexible circuits would be less painful to embed in the brains of
persons suffering from Parkinson’s disease.
Figure 4.2.1. RubberCircuit Board

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4.3. Electronic Paper
The paper and pulp industry which produces huge amounts of inorganic
pollutants such as sulphides, bleaching liquors and organic pollutants like
cellulose fibers, bark, wood, sugars, organic acids etc which leads to various
forms of pollution. The axing of trees for the purpose of use in such industry
leads to deforestation, which in turn leads soil erosion and other, related
problems.
One way to overcome this problem of resource consumption and pollution due
to extensive use of paper is to have a single sheet that can be updated regularly.
This is precisely what e-paper is all about.
Figure 4.3.1. Electronic Paper
An E-paper can be continuously updated via the Internet and even used as an
innovative display that can be rolled up tightly without any damage. These
display devices are produced using direct inkjet printing technology as it is quite

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economical and the circuit is a part of the whole display package itself. The
display typically uses E-ink, which is activated by electric charge to update the
content.
Figure 4.3.2 Electronic Paper
Researchers at Philips semi-conductors are working on a prototype whose
circuitry is made from a semi-conducting organic material called ‘pentacene’.
They laid thin films of pentacene on a flexible plastic by simply spreading a
solution of the organic material over the plastic substrate. Since the circuit is a
part of the display itself, it is economical to produce. Research is also in
progress to create full colour display, which would be four times brighter than
the devices made from liquid crystals.
A prototype is being developed in which the researchers have made use of a
single sheet covered with electronic ink that looks like ordinary paper. The

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information is stored in a portable chip, and a slim line lightweight battery
powers the display. The ink would rearrange electronically fast enough to show
even video movies.
4.4. Plastic Batteries
Batteries are indispensable sources of power in our day-to-day life. However
with their widespread use and the ineffective ways in which they are disposed
has led to serious environmental problems. To tackle this problem, researchers
have developed all plastic batteries in which both of the electrodes and the
electrolytes are made of polymers. The positive and negative electrodes are
made of thin, foil-like plastic sheets. Electrolyte is a polymer gel film placed
between the electrodes holding the battery together.
These batteries are lightweight and can be moulded into any size and shape for
use in satellites and important military equipment. Scientists are planning
practical applications of plastic batteries by linking them with solar cell
charging system to power space satellites when they are in orbit. Tests at the
Hopkin’s lab have yielded positive results. Polymer batteries can be recharged
and reused a number of times without loss of power. Besides these don’tcontain
hazardous chemicals typically found in nickel-cadmium cells and are therefore
environmentally safe.

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Figure 4.4.1. Plastic Battery
4.5. Organic LED’s
An organic light-emitting diode (OLED) is a light-emitting diode (LED) in
which the emissive electroluminescent layer is a film of organic compound that
emits light in response to an electric current. This layer of organic
semiconductor is situated between two electrodes, typically 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 game consoles and PDAs. A major area of research is the
development of white OLED devices for use in solid-state lighting applications.
There are two main families of OLED: those based on small molecules and
those employing polymers. Adding mobile ions to an OLED creates a light-
emitting electrochemical cell (LEC) which has a slightly different mode of
operation. An OLED display can be driven with a passive-matrix (PMOLED)
or active-matrix (AMOLED) control scheme. In the PMOLED scheme, each
row (and line) in the display is controlled sequentially, one by one, whereas
AMOLED control uses a thin-film transistor backplane to directly access and

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switch each individual pixel on or off, allowing for higher resolution and larger
display sizes.
Figure 4.5.1. Difference showing LED & OLED
An OLED display works without a backlight thus, it can display deep black
levels and can be thinner and lighter than a liquid crystal display (LCD). In low
ambient light conditions (such as a dark room), an OLED screen can achieve a
higher contrast ratio than an LCD, regardless of whether the LCD uses cold
cathode fluorescent lamps or an LED backlight.

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CHAPTER-5
ADVANTAGES OF POLYTRONICS
5.1. Advantages of Functional Polymers
Functional polymers are polymers with advanced optic and/or electronic
properties. Advantages of functional polymers are low cost, ease of processing
and a range of attractive mechanical characteristics for functional organic
molecules. One can adjust properties while keeping material usage low. This
opens interesting environmental perspectives. Polymer bound substances can
spread their activity without endangering people or the environment. The new
legislation will require chemical industry to come up with safe chemicals.
Functional polymers can help achieve this goal.
5.2. Advantages of Conjugated Polymers
Due to their poor processability, conductive polymers have few large-scale
applications. They have promise in antistatic materials and they have been
incorporated into commercial displays and batteries, but there have been
limitations due to the manufacturing costs, material inconsistencies, toxicity,
poor solubility in solvents, and inability to directly melt process.
Another use is for microwave-absorbent coatings, particularly radar-absorptive
coatings on stealth aircraft. Conducting polymers are rapidly gaining attraction
in new applications with increasingly processable materials with better electrical
and physical properties and lower costs. The new nanostructured forms of

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conducting polymers particularly, augment this field with their higher surface
area and better dispersability.
5.3. GeneralAdvantages
 Freedom in design
 Costeffective
 Environment friendly
 Compactportable products
 Consumes less power
 Increased picture quality in display devices
 Recycled and reused
 Light in weight and small

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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!.....

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REFERENCES
[1] Electronics for you
[2] http://www.theage.com /au-technology
[3] http://www.plastics.org
[4] http://www.AmericanPlasticsCouncil.org
[6] http://www.polymervision.com
[7] http://www.battcon.com
[8] http://www.polytronics.org
[9] http://www.polytronicseng.com