A product of nanotechnology

is the nexus of sciences. Nanotechnology is the engineering of tiny
machines – the projected ability to build things from the bottom up
using techniques and tools being developed today to make complete,
highly advanced products. It includes anything smaller than 100
nanometers with novel properties. As the pool of available resources is
being exhausted, the demand for resources that are everlasting and
eco-friendly is increasing day by day. One such form is the solar
energy. The advent of solar energy just about
all the problems. As such solar energy is very useful. But the
conventional solar cells that are used to harness solar energy are less
efficient and cannot function properly on a cloudy day.  The use of
nanotechnology in the solar cells created an opportunity to overcome
this problem, thereby increasing the efficiency. This paper deals with
an offshoot in the advancement of nanotechnology, its implementation in
solar cells and its advantage over the conventional commercial solar
pursuit of nanotechnology comprises a wide variety of disciplines:
chemistry, physics, mechanical engineering, materials science, molecular
biology, and computer science.
order to  the miniaturization of integrated circuits well into the
present century, it is likely that present day, nano-scale or
nanoelectronic device designs will be replaced with new designs for
devices that take advantage of the quantum mechanical effects that
dominate on the much smaller,nanometer scale.
Nanotechnology is often referred to as general purpose technology. That is because in its mature form it will have
impact on almost all industries and all areas of society. It offers
better built, longer lasting, cleaner, safer and smarter products for
the home, for ammunition, for medicine and for industries for ages.
These properties of nanotechnology have been made use of in solar cells.
Solar energy is really an abundant source that is renewable and
pollution free. This form of energy has very wide applications ranging
from small household items, calculators to larger things like two
wheelers, cars etc. they make use of solar cell that coverts the energy
from the sun into required form.
  Basically conventional type solar cells Photovoltaic (PV) cells are made of special materials called semiconductors
such as silicon, which is currently the most commonly used. Basically,
when light strikes the cell, a certain portion of it is absorbed within
the semiconductor material. This means that the energy of the absorbed
light is transferred to the semiconductor. The energy knocks electrons
loose, allowing them to flow freely. PV cells also all have one or more
electric fields that act to force electrons freed by light absorption to
flow in a certain direction. This flow of electrons is a current, and
by placing metal contacts on the top and bottom of the PV cell, we can
draw that current off to use externally. For example, the current can
power a calculator. This current, together with the cell’s voltage
(which is a result of its built-in electric field or fields), defines
the power (or wattage) that the solar cell can produce. Conventional
semiconductor solar cells are made by polycrystalline silicon or in the
case of highest efficiency ones crystalline gallium arsenide.
by this type of solar cell, it is observed that, only 35% of the suns
total energy falling on it could be judiciously used. Also, this is not
so favorable on cloudy days, thus creating a problem. This major draw
back led to the thought of development of a new type of solar cell
embedded with nanotechnology. The process involved in this is almost the
same as explained earlier. But the basic difference lies in the
absorption of the wavelength of light from the sun.
Various developments regarding this field are explained below:
2. INFRARED plastic solar cell:
have invented a plastic solar cell that can turn the suns power into
electric energy even on a cloudy day.       Plastic solar cells are not
new. But existing materials are only able to harness the sun’s visible
light. While half of the sun’s power lies in the visible spectrum, the
other half lies in the infrared spectrum. The new material is first
plastic compound that is able to harness infrared portion. Every warm
body emits heat. This heat is emitted even by man and by animals, even
when it is dark outside. The plastic material uses nanotechnology and
contains the 1stgeneration solar cells that can harness the
sun’s invisible infrared rays. This breakthrough made us to believe that
plastic solar cells could one day become more efficient than the
current solar cell. The researchers combined specially designed nano
particles called quantum dots with a polymer to make the plastic that
can detect energy in the infrared.
With further advances the new plastic solar cell could allow up to 30% of sun’s radiant energy to be harnessed completely when compared to only 6% in today plastic best plastic solar cells.
large amount of sun’s energy could be harnessed through solar farms and
used to power all our energy needs. This could potentially displace
other source of electrical production that produce green house gases
like coal.
energy reaching the earth is 10000 times than what we consume. If we
could cover .1% of the earth’s surface with the solar farms we could
replace all our energy habits with a source of power which is clear and
first crude solar cells have achieved efficiencies of today’s standard
commercial photovoltaics the best solar cell, which are very expensive
semiconductor laminates convert at most, 35% of the sun’s energy into
solar cell created is actually a hybrid, comprised of tiny nanorods
dispersed in an organic polymer or plastic. A layer only 200 nanometers
thick is sandwiched between electrodes and can produce at present about
.7 volts. The electrode layers and nanorod /polymer layers could be
applied in separate coats, making production fairly easy. And unlike
today’s  semiconductor-based photovoltaic devices, plastic solar cells
can be manufactured in solution in a beaker without the need for clean
rooms or vacuum chambers.
technology takes advantage of recent advances in nanotechnology
specifically the production of nanocrystals and nanorods. These are
chemically pure clusters of 100 to 100000 atoms with dimensions of the
order of a nanometer, or a billionth of a meter. Because of their small
size, they exhibit unusual and interesting properties governed by
quantum mechanics, such as the absorption of different colors of light
depending upon their size. Nanorods were made of a reliable size out of
cadmium selenide, a semi conducting material.
are manufactured in a beaker containing cadmium selenide, aiming for
rods of diameter-7 nanometers to absorb as much sunlight as possible.
The length of the nanorods may be approximately 60nanometers.Then the
nanorods are mixed with a plastic semiconductor called
p3ht-poly-(3-hexylthiophene) a transparent electrode is coated with the
mixture. The thickness, 200 nanometers-a thousandth the thickness of a
human hair-is a factor of 10 less than the micron-thickness of
semiconductor solar cells. An aluminium coating acting as the back
electrode completed the device. The nanorods act like wires. When they
absorb light of a specific wavelength, they generate an electron plus an
electron hole-a vacancy in the crystal that moves around just like an
electron. The electron travels the length of the rod until it is
collected by aluminium electrode. The hole is transferred to the
plastic, which is known as a hole-carrier, and conveyed to the
electrode, creating a current.
of the obvious improvements include better light collection and
concentration, which already are employed in commercial solar cells.
Significant improvements can be made in the plastic, nanorods mix, too,
ideally packing the nanorods closer together, perpendicular to the
electrodes, using minimal polymer, or even none-the nanorods would
transfer their electrons more directly to the electrode. In their
first-generation solar cells, the nanorods are jumbled up in the
polymer, leading to losses of current via electron-hole recombination
and thus lower efficiency.
also hope to tune the nanorods to absorb different colors to span the
spectrum of sunlight. An eventual solar cell has three layers each made
of nanorods that absorb at different wavelength.
·        Silicon possesses some nanoscale properties. This is being exploited in the development of a super thin disposable solar panel poster
which could offer the rural dwellers a cheap and an alternative source
of power. Most people living in remote areas are not linked to national
electricity grid and use batteries or run their own generator to supply
their power needs. Disposal solar panels can be made in thin sheets with
about 6-10 sheets stacked together and made into a poster can help them
to some extent in this regard. This poster could be mounted behind a
window or attached to a cabinet.
·        Like paint the compound can also be sprayed onto other materials and used as portable electricity.
·        Any chip coated in the material could power cell phone or other wireless devices.
·        A hydrogen powered car painted with the film could potentially convert energy into electricity to continually recharge the car’s battery.
·        One day solar farms
consisting   of plastic materials could be rolled across deserts to
generate enough clear energy to supply the entire planet’s power needs.
4. advantages:
solar cells are quite a lot useful in the coming future. This is
because of the    large number of advantages it has got. Some of the
major advantages are:
·        They are considered to be 30% more efficient when compared to conventional solar cells.
·        They are more efficient and more practical in application.
·        Traditional solar cells are bulky panels. This is very compact.
·        Conventional
solar cells are only used for large applications with big budgets. But
the plastic solar cells are feasible as they can be even sewn into
fabric- thus having vast applications.
·        Flexible,
roller processed solar cells have the potential to turn the sun’s power
into a clean, green, consistent source of energy.
·        The biggest problem with this is cost effectiveness.
But that could change with new material. But chemists have found a way
to make cheap plastic solar cells flexible enough to paint onto any
surface and potentially able to provide electricity for wearable
electronics or other low power devices.
·        Relatively shorter life span when continuously exposed to sunlight.
·        Could possibly require higher maintenance and constant monitoring.
6. conclusion:
solar cells help in exploiting the infrared radiation from the suns
rays. They are more effective when compared to the conventional solar
cell. The major advantage they enjoy is that they can even work on
cloudy days, which is not possible in the former. They are more compact
and less bulkier.
Though at present, cost is a major draw back, it is bound be solved in the
1. Nanomaterials: Synthesis, Properties and Applications: Edelstein, A. S., Cammarata,            R. C., Eds.; Institute of Physics Publishing: Bristol and Philadelphia, 1996.near future as scientists are working in that direction.
explained earlier, if the solar farms can become a reality, it could
possibly solve the planets problem of depending too much on the fossil
fuels, without a chance of even polluting the environment.
2. Solar energy-fundamentals, design, modeling, applications- G.N. Tiwari
3. Thin film solar cells next generation photovoltaics and its application- y Hamakawa


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