DRDO Summer internship Report,Defence lab jodhpur summer internship report,drdo training report

Research Training
Report
on
“Studies on fabrication of Dye-sensitized solar
cell and making of DC to DC mobile charger ”
At
Defence Lab, Defence Research & Development
Organisation, Jodhpur (Raj.)-342001
Duration:- 14/05/19 – 21/06/19
Submitted by:- Submitted to:-
Mr. Lalit Dr. M. S. ROY
Electrical Engineering Department Scientist ‘F’, Group Head
Sardar Vallabhbhai National Radiation & Material Application
Institute of Technology (SVNIT) Group
Surat (Gujarat)-395007 Defence Laboratory
Jodhpur(Raj.)-342001

DECLARATION
I , Mr. Lalit , hereby declare that this report is being
submitted in fulfilment of the Training Programme in
Defence Laboratory (DRDO), Jodhpur and is result
of work carried out by me under the guidance of Dr.
M. S. Roy, Mr. Narottam Prasad and Mr. Manish
Kumar.
I further declare that to my knowledge , the structure
and content of this report are original and have not been
submitted before any purpose
Mr. Lalit
B. Tech. 3 rd year (6TH
Sem.)
Electrical Engineering
SVNIT Surat

CERTIFICATE
This is to certify that Mr. Lalit , student of B.Tech in
Electrical Engineering ,from Sardar Vallabhbhai
National Institute of Technology , Surat has
successfully completed his 6th
semester training on “
Studies on fabrication of Dye-sensitized solar cell
and making of DC to DC mobile charger ” under my
supervision at Defence Research and Development
Organisation, Defence Laboratory, Jodhpur
During this tenure, we found him to be sincere and hard
working ,we take this opportunity to wish him all the
very best in Future endeavours.
Training In-charge
Dr. M. S. ROY
Scientist ‘F’
Group Head
Radiation and Materials application Group
Defence Laboratory(DRDO)
Jodhpur (Raj.) India

ACKNOWLEDGEMENT
Training is an integral part of engineering curriculum
providing engineers with first hand and practical aspects of
their studies. It gives me great pleasure in completing my
research training at Defence laboratory(DRDO) Jodhpur and
submitting the training report for the same.
I would like to thank Director Mr. Ravindra kumar for
providing me an esteemed institute for training.
I take privilege to express my sincere thanks to Dr. M. S. Roy
for giving me the opportunity to work in this prestigious institution
and supporting me constantly and channelize my work toward
more positive manner.
I express my deepest gratitude to Mr. Narottam Prasad and
Mr. Manish Kumar who teaches every minute detail of project
and shares valuable technical Knowledge

TABLE OF CONTENTS
1.Defence lab Jodhpur
i. Introduction
ii. Vision
iii. Mission
2.Solar energy scenario in India
i. Introduction
ii. Solar photovoltaic cell growth forecasts
iii. Solar Thermal Power
iv. Solar Heating
v. Rural Electrification
vi. Agricultural support
vii. Grid stabilisation
3.Solar cell overview
4.Types of solar cell
i. First generation(Si based)
ii. Second generation(thin film based)
iii. Third generation (organic and hybrid based)
5.Solar cells : theory and measurement
i. General theory
ii. Characterisation
a) Solar spectrum
b) Solar cell I-V curves
c) Measurement of efficiency
d) Fill factor and other parameters

6.Dye sensitized solar cell
i. Introduction
ii. Theory
iii. Construction
iv. Mechanism
v. Working
vi. Efficiency of DSSC
vii. Improvement of efficiency
viii. Degradation
ix. Operation
x. Advantage
xi. Disadvantage
7. Fabrication process of DSSC
i. TCO glass substrate
ii. Photo anode(working electrode)
a) Preparation of Photo anode
b) Cleaning of FTO
c) Synthesis of Nano particles
d) Development of Blocking layer
iii. Sensitizers
iv. Electrolyte
v. Preparation of Photo cathode
vi. Screen Printing
8. DC to DC Mobile Charger
9. Conclusion
10. References

DEFENCE LAB JODHPUR
INTRODUCTION
Defence Laboratory, Jodhpur (DLJ) was established in May 1959 to deal
with the problems related to environmental condition in desert and their impact
on desert warfare. The initial charter allotted to the laboratory was :
"Undertaking field trials on weapons and equipment which were either newly
designed or developed in the country or were being manufactured indigenously
with imported know-how, besides conducting basic research as applicable in the
arid zone, physiological studies, Radio-wave propagation studies and solar
energy."
Defence Laboratory (DLJ) is western most located, an strategically important
laboratory of the Defence Research and Development Organisation (DRDO).
Previously located in Ratanada Palace (now a DRTC training centre), Jodhpur,
now shifted to the New Technical Complex (NTC). It is responsible for the
development and manufacture of electronics and materials required for modern
warfare and weapon systems. Main research fields are Materials and electronics.
Its mission is development of Radio Communication Systems, Data links,
Satellite Communication Systems, Millimeter Wave Communication systems.
There are three divisions in laboratory:
1. Camouflage and Low observation technology Division
2. NRMA(Nuclear Radiation's Management and Applications) Division
3. Desert Environment Science and Technology Division
The name suggests the primary functions of these groups, further in these
divisions there are various groups working on different technologies. DLJ
(Defence Laboratory, Jodhpur) has developed several nuclear radiation
monitoring systems and camouflage techniques for the Armed Forces of India.
Few scientists are also engaged in field of microbiology and biotechnology.

VISION & MISSION
Vision
To achieve excellence and self reliance in the areas of Multispectral
Camouflage and Low Observable Technologies, provide solutions to Desert
related problems, and develop Nuclear Radiation Sensor Technologies and
Applications of Radio isotopes.
Mission
To become a centre of excellence in Camouflage, Desert Sciences & Nuclear
Radiation Management Technologies.

SOLAR ENERGY SCENARIO IN INDIA
Solar power in India is a fast developing industry. The country's solar installed
capacity reached 28.18 GW as of 31 March 2019. The Indian government had
an initial target of 20 GW capacity for 2022, which was achieved four years
ahead of schedule. In 2015 the target was raised to 100 GW of solar capacity
(including 40 GW from rooftop solar) by 2022, targeting an investment
of US$100 billion.
India expanded its solar-generation capacity 8 times from 2,650 MW on 26 May
2014 to over 20 GW as on 31 January 2018. The country added 3 GW of solar
capacity in 2015-2016, 5 GW in 2016-2017 and over 10 GW in 2017-2018,
with the average current price of solar electricity dropping to 18% below the
average price of its coal-fired counterpart.
Rooftop solar power accounts for 3.4 GW, of which 70% is industrial or
commercial. In addition to its large-scale grid-connected solar photovoltaic
(PV) initiative, India is developing off-grid solar power for local energy
needs. Solar products have increasingly helped to meet rural needs; by the end
of 2015 just under one million solar lanterns were sold in the country, reducing
the need for kerosene. That year, 118,700 solar home lighting systems were
installed and 46,655 solar street lighting installations were provided under a
national program; just over 1.4 million solar cookers were distributed in India.
The International Solar Alliance (ISA), proposed by India as a founder member,
is headquartered in India.
SOLAR PHOTOVOLTAIC CELL GROWTH FORECASTS
In August 2016, the forecast for solar photovoltaic installations was about 4.8
GW for the calendar year. About 2.8 GW was installed in the first eight months
of 2016, more than all 2015 solar installations. India's solar projects stood at
about 21 GW, with about 14 GW under construction and about 7 GW to be
auctioned The country's solar capacity reached 19.7 GW by the end of 2017,
making it the third-largest global solar market mid-2018 the Indian power
minister RK Singh flagged a tender for a 100GW solar plant at an event in
Delhi, while discussing a 10GW tender due to be issued in July that year (at the
time, a world record). He also increased the government target for installed

Solar Thermal Power
The installed capacity of commercial solar thermal power plants (non storage
type) in India is 227.5 MW with 50 MW in Andhra Pradesh and 177.5 MW in
Rajasthan Solar thermal plants with thermal storage are emerging as cheaper
(Rs 3.97/KWh) and clean load following power plants to supply electricity
round the clock, working as dispatchable generation. Proper mix of solar
thermal (thermal storage type) and solar PV can fully match the load
fluctuations without the need of costly battery storage
The existing solar thermal power plants (non-storage type) in India, which are
generating costly intermittent power on daily basis, can be converted into
storage type solar thermal plants to generate 3 to 4 times more base load power
at cheaper cost and not depend on government subsidies.
Hybrid Solar Panel
Solar power, generated mainly during the daytime in the non-monsoon period,
complements wind which generate power during the monsoon months in India.
Solar panels can be located in the space between the towers of wind-power
plants. It also complements hydroelectricity, generated primarily during India's
monsoon months. Solar-power plants can be installed near existing hydropower
and pumped-storage hydroelectricity, utilizing the existing power transmission
infrastructure and storing the surplus secondary power generated by the solar
PV plants
During the daytime, the additional auxiliary power consumption of a solar
thermal storage power plant is nearly 10% of its rated capacity for the process
of extracting solar energy in the form of thermal energy. This auxiliary power
requirement can be made available from cheaper solar PV plant by envisaging
hybrid solar plant with a mix of solar thermal and solar PV plants at a site. Also
to optimise the cost of power, generation can be from the cheaper solar PV plant
(33% generation) during the daylight whereas the rest of the time in a day is
from the solar thermal storage plant (67% generation from Solar power
tower and parabolic trough types) for meeting 24 hours base load power. When
solar thermal storage plant is forced to idle due to lack of sunlight locally during
cloudy days in monsoon season, it is also possible to consume (similar to a
lesser efficient, huge capacity and low cost battery storage system) the cheap
excess grid power when the grid frequency is above 50 hz for heating the hot
molten salt to higher temperature for converting stored thermal energy in to
electricity during the peak demand hours when the electricity sale price is
profitable.

Solar Heating
Generating hot water or air or steam using concentrated solar reflectors, is
increasing rapidly. Presently concentrated solar thermal installation base for
heating applications is about 20 MW in India and expected to grow rapidly.
Cogeneration of steam and power round the clock is also feasible with solar
thermal CHP plants with storage capacity.
Bengaluru has the largest deployment of roof-top solar water heaters in India,
generating an energy equivalent of 200 MW It is India's first city to provide a
rebate of ₹50 (72¢ US) on monthly electricity bills for residents using roof-top
thermal systems, which are now mandatory in all new structures. Pune has also
made solar water heaters mandatory in new buildings Photovoltaic
thermal (PVT) panels produce simultaneously the required warm water/air
along with electricity under sunlight.
Rural Electrification
The lack of an electricity infrastructure is a hurdle to rural India's development.
India's power grid is under-developed, with large groups of people still living
off the grid. In 2004, about 80,000 of the nation's villages still did not have
electricity; of them, 18,000 could not be electrified by extending the
conventional grid. A target of electrifying 5,000 such villages was set for
the 2002–2007 Five-Year Plan. By 2004 more than 2,700 villages and hamlets
were electrified, primarily with solar photovoltaic systems. The development of
inexpensive solar technology is considered a potential alternative, providing an
electricity infrastructure consisting of a network of local-grid clusters with
distributed electricity generation It could bypass (or relieve) expensive, long-
distance, centralized power-delivery systems, bringing inexpensive electricity to
large groups of people. In Rajasthan during FY2016-17, 91 villages have been
electrified with a solar standalone system and over 6,200 households have
received a 100W solar home-lighting system.
India has sold or distributed about 1.2 million solar home-lighting systems and
3.2 million solar lanterns, and has been ranked the top Asian market for solar
off-grid products.
Lamps and lighting
By 2012, a total of 4,600,000 solar lanterns and 861,654 solar-powered home
lights were installed. Typically replacing kerosene lamps, they can be purchased
for the cost of a few months' worth of kerosene with a small loan. The Ministry
of New and Renewable Energy is offering a 30- to 40-percent subsidy of the
cost of lanterns, home lights and small systems (up to 210 Wp) Twenty million
solar lamps are expected by 2022

Agricultural support
Solar photovoltaic water-pumping systems are used for irrigation and drinking
water. Most pumps are fitted with a 200–3,000 W (0.27–4.02 hp) motor
powered with a 1,800 Wp PV array which can deliver about 140,000 litres
(37,000 US gal) of water per day from a total hydraulic head of 10 m (33 ft). By
30 September 2006 a total of 7,068 solar photovoltaic water pumping systems
were installed, and 7,771 were installed by March 2012 During hot sunny
daytime when the water needs are more for watering the fields, solar pumps
performance can be improved by maintaining pumped water flowing/sliding
over the solar panels to keep them cooler and clean. Solar driers are used to dry
harvests for storage. Low cost solar powered bicycles are also available to ply
between fields and village for agricultural activity, etc.
Rainwater harvesting
In addition to solar energy, rainwater is a major renewable resource of any area.
In India, large areas are being covered by solar PV panels every year. Solar
panels can also be used for harvesting most of the rainwater falling on them and
drinking-quality water, free from bacteria and suspended matter, can be
generated by simple filtration and disinfection processes, as rainwater is very
low in salinity. Good quality water resources, closer to populated areas, are
becoming a scarcity and increasingly costly for consumers. Exploitation of
rainwater for value-added products like bottled drinking water makes solar PV
power plants profitable even in high rainfall and cloudy areas by the increased
income from drinking water generation.
Refrigeration and Air conditioning
Thin-film solar cell panels offer better performance than crystalline silica solar
panels in tropical hot and dusty places like India; there is less deterioration in
conversion efficiency with increased ambient temperature, and no partial
shading effect. These factors enhance the performance and reliability (fire
safety) of thin-film panels. Maximum solar-electricity generation during the hot
hours of the day can be used for meeting residential air-conditioning
requirements regardless of other load requirements, such as refrigeration,
lighting, cooking and water pumping. Power generation of photovoltaic
modules can be increased by 17 to 20 percent by equipping them with a tracking
system.
Residential electricity consumers who are paying higher slab rates more
than ₹5(7.2¢ US) per unit, can form in to local groups to install collectively roof
top off-grid solar power units (without much battery storage) and replace the
costly power used from the grid with the solar power as and when
produced Hence power drawl from the grid which is an assured power supply
without much power cuts nowadays, serves as cheaper back up source when

grid power consumption is limited to lower slab rate by using solar power
during the day time. The maximum power generation of solar panels during the
sunny daytime is complementary with the enhanced residential electricity
consumption during the hot/summer days due to higher use of cooling
appliances such as fans, refrigerators, air conditioners, desert coolers, etc. It
would discourage the Discoms to extract higher electricity charges selectively
from its consumers. There is no need of any permission from Discoms similar
to DG power sets installation. Cheaper discarded batteries of electric
vehicle can also be used economically to store the excess solar power generated
in the daylight
Grid stabilisation
Solar-power plants equipped with battery-storage systems where net energy
metering is used can feed stored electricity into the power grid when its
frequency is below the rated parameter (50 Hz) and draw excess power from the
grid when its frequency is above the rated parameter. Excursions above and
below the rated grid frequency occur about 100 times daily The solar-plant
owner would receive nearly double the price for electricity sent into the grid
compared to that consumed from the grid if a frequency-based tariff is offered
to rooftop solar plants or plants dedicated to a distribution substation power-
purchase agreement (PPA) is not needed for solar plants with a battery storage
system to serve ancillary-service operations and transmit generated electricity
for captive consumption using an open-access facility Battery storage is popular
in India, with more than 10 million households using battery backup during load
shedding. Battery storage systems are also used to improve the power
factor. Solar PV or wind paired with four-hour battery storage systems is
already cost competitive, without subsidy, as a source of dispatchable
generation compared with new coal and new gas plants in India”.
Battery storage is also used economically to reduce daily/monthly peak power
demand for minimising the monthly demand charges from the utility to the
commercial and industrial establishments. Construction power tariffs are very
high in India. Construction power needs of long gestation mega projects can be
economically met by installing solar PV plants for permanent service in the
project premises with or without battery storage for minimising use of Standby
generator sets or costly grid power.

SOLAR CELL OVERVIEW
A solar cell is a key device that converts light energy into electrical energy in
a photovoltaic energy conversion. In most cases, semiconductor is used for solar
cell material. The energy conversion consists of absorption of light (photon)
energy producing electron–hole pairs in a semiconductor and charge carrier
separation. The p–n junction is commonly used for solar cell. The important
role of p–n junction is the charge separation of light-induced electrons and
holes. A p–n junction is used for charge carrier separation in most cases. The
concepts of solar cell using nanocrystalline materials are also explained.
Because the solar cells based on nanocrystalline materials are complicated as
compared to the conventional p–n junction solar cell, Solar cells made from
multi- or monocrystalline silicon wafers are large-area semiconductor p–n
junctions. Technically, solar cells have a relatively simple structure, and the
theory of p–n junctions was already established decades ago. The generally
accepted model for describing them is the so-called two-diode model. However,
the current–voltage characteristics of industrial solar cells, particularly of those
made from multicrystalline silicon material, show significant deviations from
the established diode theory. These deviations regard the forward and the
reverse dark characteristics as well as the relation between the illuminated
characteristics and the dark ones. In the last few years, it has been found that the
characteristics of industrial solar cells can only be understood by taking into
account local in homogeneities of the dark current flow. Such in homogeneities
can be investigated by applying local imaging techniques like lock-
in thermography and luminescence imaging. Meanwhile, based on these and
other investigations, the basic properties of industrial silicon solar cells are well
understood. This contribution first summarizes the established theory of the
operation of solar cells, which generally assumes homogeneous current flow.
Then the predictions according to this theory are compared to the
experimentally measured characteristics of industrial solar cells, which largely
deviate from these predictions. In the following sections, the most important
experimental and theoretical results explaining these deviations are introduced,
leading to the present state of physical understanding of the dark and
illuminated characteristics of multicrystalline industrial solar cells.
Solar Panel or Solar Module: Solar cells are wired in series and placed
into a frame. The size of the frame can vary with manufacturers … as a result of
the technology used. A protective coating on the top covers and protects (and
sometimes increases the output) of the solar cells. Any number of cells can be
connected in series and most commercial modules sold today incorporate 72
cells. .

TYPES OF SOLAR CELL
There are several types of solar cells, which are typically categorised into three
generations. The first generation (known as conventional devices) are based
upon crystalline silicon, a well-studied inorganic semiconductor. The second
generation are the thin-film devices, which includes materials that can create
efficient devices with thin films (nanometre to tens of micrometres range). The
third generation are the emerging photovoltaic – technologies which are still
undergoing research to reach commercialisation. Third generation solar cell
depends on organic and hybrid material based.
The first and second generations contain the most-studied photovoltaic
materials: silicon, gallium arsenide, cadmium telluride, and copper indium
gallium selenide. These materials are all inorganic semiconductors, and
generally work in the most direct manner: a photon is absorbed – creating an
exciton, which is thermally dissociated (inorganic semiconductors typically
have high dielectric constants) and subsequently transported to the electrodes
via an electric field.
First Generation Solar Cells
Traditional solar cells are made from silicon, are currently the most efficient
solar cells available for residential use and account for around 80+ percent of all
the solar panels sold around the world. Generally silicon based solar cells are
more efficient and longer lasting than non silicon based cells. However, they are
more at risk to lose some of their efficiency at higher temperatures (hot sunny
days), than thin-film solar cells.
The types are based on the type of silicon used, specifically:
1. Monocrystalline Silicon Cells
The oldest solar cell technology and still the most popular and efficient are solar
cells made from thin wafers of silicon. These are called monocrystalline solar
cells because the cells are sliced from large single crystals that have been
painstakingly grown under carefully controlled conditions. Typically, the cells
are a few inches across, and a number of cells are laid out in a grid to create a
panel.
Relative to the other types of cells, they have a higher efficiency (up to 24.2%),
meaning you will obtain more electricity from a given area of panel. This is

useful if you only have a limited area for mounting your panels, or want to keep
the installation small for aesthetic reasons. However, growing large crystals of
pure silicon is a difficult and very energy-intensive process, so the production
costs for this type of panel have historically are the highest of all the solar panel
types.
Production methods have improved though, and prices for raw silicon as well as
to build panels from monocrystalline solar cells have fallen a great deal over the
years, partly driven by competition as other types of panel have been produced.
Another issue to keep in mind about panels made from monocrystalline silicon
cells is that they lose their efficiency as the temperature increases about 25˚C,
so they need to be installed in such a way as to permit the air to circulate over
and under the panels to improve their efficiency.
2. Polycrstalline Silicon Cells
It is cheaper to produce silicon wafers in molds from multiple silicon crystals
rather than from a single crystal as the conditions for growth do not need to be
as tightly controlled. In this form, a number of interlocking silicon crystals grow
together. Panels based on these cells are cheaper per unit area than
monocrystalline panels - but they are also slightly less efficient (up to 19.3%).
For more information about polycrystalline solar cells, their advantages and
disadvantages, and information about leading panel manufacturers click here.
Second Generation Solar Cells
Second-generation solar cells are usually called thin-film solar cells because
when compared to crystalline silicon based cells they are made from layers of
semiconductor materials only a few micrometers thick. The combination of
using less material and lower cost manufacturing processes allow the
manufacturers of solar panels made from this type of technology to produce and
sell panels at a much lower cost.
There are basically three types of solar cells that are considered in this category,
amorphous silicon and two that are made from non-silicon materials namely
cadmium telluride (CdTe), and copper indium gallium selenide (CIGS).
Together they accounted for around 16.8% of the panels sold in 2009.
First Solar, the number one producer and seller of solar panels in the world
currently makes their solar cells using cadmium telluride.

New Recently a Company based in Idaho has come up with a thin-film
monocrystalline solar cell - that uses about 20% of the crystalline silicon in
current silicon based cells and has number of advantages.
1. Amorphous Silicon Cells
most solar cells used in calculators and many small electronic devices are made
from amorphous silicon cells.
Instead of growing silicon crystals as is done in making the two previous types
of solar cells, silicon is deposited in a very thin layer on to a backing substrate –
such as metal, glass or even plastic. Sometimes several layers of silicon, doped
in slightly different ways to respond to different wavelengths of light, are laid
on top of one another to improve the efficiency. The production methods are
complex, but less energy intensive than crystalline panels, and prices have been
coming down as panels are mass-produced using this process.
One advantage of using very thin layers of silicon is that the panels can be made
flexible. The disadvantage of amorphous panels is that they are much less
efficient per unit area (up to 10%) and are generally not suitable for roof
installations you would typically need nearly double the panel area for the same
power output. Having said that, for a given power rating, they do perform better
at low light levels than crystalline panels - which is worth having on a dismal
winter's day, and are less likely to lose their efficiency as the temperature
climbs.
However, there flexibility makes them an excellent choice for use in making
building integrated PV (e.g., roofing shingles), for use on curved surfaces, or
even attached to a flexible backing sheet so that they can even be rolled up and
used when going camping / backpacking, or put away when they are not
needed!
2. Cadmium Telluride
Cadmium telluride (CdTe) is a high-efficiency thin-film photovoltaic
technology which has achieved an efficiency of 22.1%. CdTe has a similar
band gap to GaAs at 1.44 eV, giving it the same advantages as seen in GaAs –
good absorption in thin films and low photon energy losses. This material also
boasts the possibility to be flexible, very low costs, and it has produced
commercial solar panels that are cheaper than silicon with much shorter energy

payback times (although with lower efficiency). Despite these advantages, there
are some issues – cadmium is highly toxic and tellurium is very rare, making
the long-term viability of this technology uncertain for now.
3. Copper Indium Gallium Selenide
Copper indium gallium selenide (CIGS) has achieved similar performances to
CdTe devices, with a peak of 22.6%. The compound has the chemical formula
CuInxGa(1-x)Se2 where x can take a value between 0 and 1. This tunability of
the chemical structure enables the band gap of the material to be varied between
1.0 eV (x = 1, pure copper indium selenide) and 1.7 eV (x = 0, pure copper
gallium selenide). However, like GaAs cells, CIGS are expensive to fabricate
and result in solar panels that cannot compete with the current commercial
technologies. Furthermore, like tellurium, indium is very rare, limiting the long-
term potential of this technology.
Third Generation Solar Cells
Currently there is a lot of solar research going on in what is being referred to in
the in the industry as Third-generation solar cells.
The third generation of photovoltaics – also known as the emerging
photovoltaic technologies – includes hybrid, dye-sensitised, organic, and
perovskite solar cells.
This new generation of solar cells are being made from variety of new materials
besides silicon, including nanotubes, silicon wires, solar inks using conventional
printing press technologies, organic dyes, and conductive plastics. The goal of
course is to improve on the solar cells already commercially available – by
making solar energy more efficient over a wider band of solar energy (e.g.,
including infrared), less expensive so it can be used by more and more people,
and to develop more and different uses.
Currently, most of the work on third generation solar cells is being done in the
laboratory, and being developed by new companies and for the most part is not
commercially available.

1. Hybrid Silicon Cells
One recent trend in the industry is the emergence of hybrid silicon cells and
several companies are now exploring ways of combining different materials to
make solar cells with better efficiency, longer life, and at reduced costs.
Recently, Sanyo introduced a hybrid HIT cell whereby a layer of amorphous
silicon is deposited on top of single crystal wafers. The result is an efficient
solar cell that performs well in terms of indirect light and is much less likely to
lose efficiency as the temperature climbs.
2. Dye-Sensitised
Structure and operation of a dye-sensitised solar cell. Photons are absorbed by
the dye, and the generated electron and hole transfer to the oxide scaffold and
electrolyte respectively, where they are transported to the appropriate
electrodes.
Dye-sensitised solar cells (DSSCs) use organic dyes to absorb light. These dyes
are coated onto an oxide scaffold (typically titanium oxide) which are immersed
in a liquid electrolyte. The dyes absorb the light, and the excited electron is
transferred to the oxide scaffold, whilst the hole is transferred to the electrolyte.
The charge carriers can then be collected at the electrodes. These cells are less
efficient than inorganic devices, but have the potential to be much cheaper,
produced via roll-to-roll printing, semi-flexible, and semi-transparent. However,
issues still exist with use of a liquid electrolyte due to temperature stability (can
potentially freeze or expand), the use of expensive materials, and volatile
organic compounds.

3. Organic
Organic solar cells (OSCs) use organic semiconducting polymers or small
molecules as the photoactive materials. To date, efficiencies of 11.5% have
been achieved by this technology. These cells work similarly to inorganic
devices. However, organic semiconductors generally have low dielectric
constants, meaning that the generated exciton cannot be thermally dissociated.
Instead, the exciton must be transported to an interface with a material that has
an energy level offset greater than the binding energy of the photon. Here, the
electron (or hole) can transfer to the other material and split the exciton,
allowing the charge carriers to be collected (as shown in Figure 3). As excitons
can typically only diffuse approximately 10 nm before the electron and hole
recombine, this limits the thickness, structure, and ultimately – the performance
of an organic photovoltaic cell. Despite this, these devices hold some significant
advantages over inorganic devices, including: low cost of materials, lightweight,
strong and tuneable absorption characteristics, flexibility, and the potential to be
fabricated using roll-to-roll printing techniques. Currently, organic materials
suffer from stability issues arising from photochemical degradation.
4. Perovskite
Perovskite solar cells (PSCs) use perovskite materials (materials with the crystal
structure ABX3) as their light-absorbing layer. Perovskites were introduced to
the field relatively recently, with the first use in a photovoltaic device reported
in 2006 (where it was the dye in a DSSC achieving 2.2%). However, 2012 is
considered the birth of the field, due to the publication of a landmark paper in
which an efficiency of 10.9% was achieved. Since then the peak efficiency has
risen to 22.1%, making PSCs the fastest-improving solar technology. These
materials have remarkable properties, including strong tuneable absorption
characteristics and ambipolar charge transport. They can also be processed from
solution in ambient conditions.
perovskite solar cell.
There are still issues with stability and the use of toxic materials (such as lead)
preventing the technology from being commercialised, but the field is still

relatively young and very active. For more detailed information about
perovskites, see our perovskite guide.
Highest efficiency of Solar cell
Solar cell type Highest efficiency
Monocrystalline silicon(mono-si) 25.3%
Polycrystalline silicon (multi-Si) 21.9%
Amorphous silicon (a-Si) 14.0%
Monocrystalline gallium arsenide
(GaAs)
28.8%
Cadmium telluride (CdTe) 22.1%
Copper indium gallium selenide
(CIGS)
22.6%
Dye-sensitised (DSSC) 11.9%
Organic (OSC) 11.5%
Perovskite (PSC) 22.1%

The Shockley-Queisser limit
Shockley–Queisser limit or detailed balance limit refers to the calculation of
the maximum theoretical efficiency of a solar cell made from a single p-n
junction. It was first calculated by William Shockley and Hans Queisser
The Shockley–Queisser limit is calculated by examining the amount of
electrical energy that is extracted per incident photon. The calculation places
maximum solar conversion efficiency around 33.7% assuming a single pn
junction with a band gap of 1.4 eV (using an AM 1.5 solar spectrum).
Therefore, an ideal solar cell with incident solar radiation will generate 337
Wm-2 . When the solar radiation is modelled as 6000 K blackbody radiation the
maximum efficiency occurs when the bandgap energy Eg=1.4 eV.
The maximum efficiency of a single-junction solar cell as calculated by the
Shockley– Queisser model as a function of bandgap energy.The incident solar
spectrum is approximated as a 6000 K blackbody spectrum.
The Critical SQ Limit Assumptions:
 One semiconductor material (excluding doping materials) per solar cell.
 One p/n junction per solar cell.
 The sunlight is not concentrated - a "one sun" source.

 All energy is converted to heat from photons greater than the band gap.
Where Does The 67% Of Energy Loss Go?
 47% of the solar energy gets converted to heat.
 18% of the photons pass through the solar cell.
 02% of energy is lost from local recombination of newly created holes and
electrons.
 33% of the sun's energy is theoretically converted to electricity.
 100% total sun's energy.
If the theoretical limit for silicon cells is about 30%, what happens to the other
6% that is lost from the best production cell efficiency of 24%? Some sunlight
is always reflected off the surface of the cell even though the surface is usually
texturized and coated with an anti-reflective coating. In addition there are some
losses at the junction of the silicon cell with the electrical contacts that carry the
current to the load. Finally, there are some losses due to manufacturing
impurities in the silicon.
What Electro-Magnetic Waves Are Absorbed By A
Solar Cell?
Shown to the left is the complete spectrum of electro-magnetic radiation. The
long radio waves at the right are the weakest. The most powerful rays (gamma
rays) are very short and to the left.

For a semiconductor electron to move into an external load circuit, its energy
level must be increased from its normal valence level (tightly bound to one
atom) to its higher energy conduction level (free to move around). The amount
of energy to boost it to the higher level is called the "band gap" energy.
Only photons with at least the band gap energy will be able to free electrons to
create a current. Sunlight photons with less than the band gap energy will
simply pass through the solar cell. Put in terms of radiation, all the photons in
the visible spectrum are strong enough to cause electrons to jump the band gap.
Some infrared, all microwave, and all radio waves do not have enough energy
and pass right through the solar cell.
In the "sunlight energy distribution" chart to the left, only the mustard colored
photons can be "absorbed" and create electricity in a crystalline silicon cell.
Absorption of electromagnetic radiation is the process by which the energy of a
photon from the sun is transformed into other forms of energy for example
electricity or heat.
The red colored wavelenghts do not have enough energy and the yellow ones have
too much energy.
There are three primary considerations in the calculation.
1. Blackbody radiation :The blackbody radiation from solar cell at room
temperature (300 K) cannot be captured by the cell, and represents about 7% of
the available incoming energy. Energy lost in a cell is generally turned into
heat, so any inefficiency in the cell increases the cell temperature when it is
placed in sunlight. As the temperature of the cells increases, the blackbody

radiation also increases, until equilibrium is reached. In practice this equilibrium
is normally reached at temperatures as high as 360 K, and cells normally
operate at lower efficiencies than their room temperature rating.
2. Recombination: Recombination places an upper limit on the rate of electron-
hole production. In silicon this reduces the theoretical performance under
normal operating conditions by another 10% over and above the thermal losses.
Voc is limited by recombination. The limit for the maximum open-circuit
current of a solar cell within the Shockley-Queisser model. The red dotted line
is Voc=Eg.
4. Spectrum losses :
The limit for short-circuit current density (i.e., current density at zero
voltage). This assumes that each solar photon gets converted into an
electron that flows through the circuit. At higher bandgaps, there are
fewer photons above the bandgap, and therefore the current density
decreases. (From Shockley–Queisser limit Wiki pages) Of the 1,000
W/m² in AM1.5 solar radiation, about 19% of that has less than 1.1 eV of
energy, and will not produce power in a silicon cell. This accounts for
about 33% of the incident sunlight, meaning that from spectrum losses
alone there is a theoretical conversion efficiency of about 48%, ignoring
all other factors.

Solar Cells: Theory and Measurement
A solar cell is a device that converts light into electricity via the ‘photovoltaic
effect. They are also commonly called ‘photovoltaic cells’ after this
phenomenon, and also to differentiate them from solar thermal devices. The
photovoltaic effect is a process that occurs in some semiconducting materials,
such as silicon. At the most basic level, the semiconductor absorbs a photon,
exciting an electron which can then be extracted into an electrical circuit by
built-in and applied electric fields.
General Theory
The main component of a solar cell is the semiconductor, as this is the part that
converts light into electricity. Semiconductors can carry out this conversion due
to the structure of their electron energy levels. Electron energy levels are
generally categorised into two bands: the ‘valence band’ and the ‘conduction
band’. The valence band contains the highest occupied electron energy levels,
whilst the conduction band contains the lowest unoccupied electron energy
levels. The energy difference between the top of the valence band and bottom of
the conduction band is known as the ‘band gap’ (Eg). In a conductor, there is no
band gap as the valence band is not filled completely - thus allowing the free
movement of electrons through the material. Insulators have very large band
gaps which require copious amounts of energy to cross – and as such, inhibits
the movement of electrons from the valence band to the conduction band.
Conversely, the band gap in semiconductors is relatively small, enabling some
electrons to move to the conduction band by injecting small amounts of energy.
Energy bands for metals, insulators, and semiconductors.

This small band gap is what enables some semiconductors to generate
electricity using light. If a photon incident on the semiconductor has energy (Eγ)
greater than the band gap, it will be absorbed - enabling an electron to transfer
from the valence band into the conduction band. This process is known as
‘excitation’. With the electron now in the conduction band, an unoccupied state
is left in the valence band. This is known as a ‘hole’, and behaves like a particle
analogous to an electron in the conduction band (albeit with positive charge).
Due to their opposite charge, the excited electron and hole are coulomb
basically bound in a state known as an ‘exciton’. This exciton must be split
(also known as ‘dissociation’) before the charge carriers can be collected and
used. The energy required to do this is dependent on the dielectric constant (εr)
of the material. This describes the level of screening between charges in a
semiconducting material and affects the binding energy of the exciton.
Basic operation of a solar cell.
a) A photon is absorbed by the semiconductor
b) an electron is promoted from the valence band to the conduction band,
leaving a hole in the valence band.
c) The electron and hole are transported to electrodes to be collected.
In materials with high εr, excitons have low binding energies - enabling
dissociation to occur thermally at ambient temperatures. Excitons in materials

with low εr have high binding energies, preventing thermal dissociation – thus
requiring a different method of dissociation. A common method is to get the
exciton to an interface between materials with energy levels that have an offset
greater than the exciton’s binding energy. This enables the electron (or hole) to
transfer to the other material, and dissociate the exciton.
Solar cell operation for a material with a low dielectric constant.
a) A photon is absorbed by material 1, generating an exciton.
b) The exciton diffuses to an interface with material 2 which has offset energy
levels.
c) Here, the electron (or hole) transfers to material 2, and the exciton is split.
d) Finally, the charges are transported to the electrodes.
Once dissociated, the free charges diffuse to the electrodes of the cell (where
they are collected) – this is assisted by built-in and applied electric fields. The
built-in electric field of a device arises from the relative energy levels of the
materials that make up the cell. However, the origin of the built-in field depends
on the type of semiconductor being used. For inorganic semiconductors such as
silicon, other materials are often added to the semiconductor (a process known
as doping) to create regions of high (n-type) and low (p-type) electron density.

When these regions are in contact, charges will build up on either side of the
interface, creating an electric field directing from the n-type to the p-type
region. In devices using organic semiconductors, the built-in field arises from
the difference between the work functions of the electrodes of the device.
The size of the band gap is also very important, as this affects the energy that
can be harvested by the solar cell. If Eγ > Eg, then the photon will be absorbed,
and any energy in excess of Eg will be used to promote the electron to an energy
level above the conduction band minimum. The electron will then relax down to
the conduction band minimum, resulting in the loss of the excess energy.
However, if Eγ < Eg, then the photon will not be absorbed, again resulting in lost
energy. (Note, the wavelength of a photon decreases as its energy increases).
When considering the solar spectrum, it can therefore be seen that a too large
Eg will result in a significant number of photons not being absorbed. On the
other hand, a too low Eg means that a large number of photons will be absorbed,
but a significant amount of energy will be lost due to the relaxation of electrons
to the conduction band minimum. Due to this trade-off, it is possible to
calculate the theoretical maximum efficiency of a standard photovoltaic device,
as well as estimate the optimum band gap for a photovoltaic material. Shockley
and Queisser determined the theoretic maximum efficiency to be approximately
33% in 1961, which corresponds to a band gap of 1.34 eV (~930 nm).
The spectral irradiance and photon flux of the Sun. The green line represents
the wavelength corresponding to optimum band gap energy (~930 nm). Data
was provided by the National Renewable Energy Laboratory, Golden, CO.

Characterisation
1. Solar Spectrum
The characterisation of a solar cell determines how well it performs under solar
illumination. The spectrum of the Sun is approximately that of a black body
with a temperature of 5780 K. This peaks in the visible range and has a long
infra-red tail. However, this spectrum is not used for characterisation as the light
must pass through the Earth’s atmosphere (which absorbs a significant portion
of the solar radiation) to reach the surface. Instead, the industry standard is
AM1.5G (air mass 1.5 global), the average global solar spectrum after passing
through 1.5 atmospheres. This has a power density of 100 mW.cm-2
and is
equivalent to average solar irradiation at mid-latitudes (such as in Europe or the
USA).
AM0 and AM1.5 solar spectrum. Data courtesy of the National Renewable
Energy Laboratory, Golden, CO.
2. Solar Cell IV Curves
The key characteristic of a solar cell is its ability to convert light into electricity.
This is known as the power conversion efficiency (PCE) and is the ratio of
incident light power to output electrical power. To determine the PCE, and other
useful metrics, current-voltage (IV) measurements are performed. A series of
voltages are applied to the solar cell while it is under illumination. The output
current is measured at each voltage step, resulting in the characteristic 'IV curve'

seen in many research papers. An example of this can be seen below in Figure
6, along with some important properties that can be determined from the IV
measurement. It should be noted that generally, current density (J) is used
instead of current when characterising solar cells, as the area of the cell will
have an effect on the magnitude of the output current (the larger the cell, the
more current).
Perform your own measurements using the Solar Cell I-V Test
System.
Typical IV curve of a solar cell plotted using current density, highlighting the
short-circuit current density (Jsc), open-circuit voltage (Voc), current and
voltage at maximum power (JMP and VMP respectively), maximum power
point (PMax), and fill factor (FF).

The properties highlighted in the figure are:
 JMP – Current density at maximum power
 VMP – Voltage at maximum power
 PMax – The maximum output power (also known as maximum power
point)
 Jsc – Short-circuit current density
 Voc – Open-circuit voltage
The PCE can be calculated using the following equation:
Here, Pout (Pin) is the output (input) power of the cell, FF is the fill factor, and
Jsc and Voc are the short-circuit current density and open-circuit voltage
respectively.
The short-circuit current density is the photo generated current density of the
cell when there is no applied bias. In this case, only the built-in electric field
within the cell is used to drive charge carriers to the electrodes. This metric is
affected by:
 Absorption characteristics of the photoactive layer
 Charge generation, transport, and extraction efficiency
The open-circuit voltage is the voltage at which the applied electric field cancels
out the built-in electric field. This removes all driving force for the charge
carriers, resulting in zero photocurrent generation. This metric is affected by:
 Energy levels of the photoactive materials
 Work functions of the electrode materials
 Charge carrier recombination rate
The fill factor is the ratio of the actual power of the cell to what its power would
be if there were no series resistance and infinite shunt resistance (explained
later). This is ideally as close as possible to 1, and can be calculated using the
following equation:
Here, JMP and VMP are the current density and voltage of the cell at
maximum power respectively.

Approximate values of the series and shunt resistances can be
calculated from the inverse of the gradient of a cell’s JV curve at the
Voc and Jsc respectively.
A solar cell is a diode, and therefore the electrical behaviour of an ideal
device can be modelled using the Shockley diode equation:
Here, Jph is the photo generated current density, JD is the diode current
density, J0 is the dark saturation current density (current density flowing
through the diode under reverse bias in the dark), V is the voltage, and T
is the temperature. The final 2 symbols, e and kB, are the elementary
charge (1.6 x 10-19
C) and the Boltzmann constant (1.38 x 10-23
m2
.kg.s-
2
.K-1
) respectively. However, in reality, no device is ideal and so the
equation must be modified to account for potential losses that may arise:
Here, n is the diode ideality factor and all other symbols have their
previous meanings. Using this equation, a solar cell can be modelled
using an equivalent circuit diagram, which is shown below:
Figure 7: The
equivalent circuit of a solar cell, the symbols correspond to the symbols in the
modified Shockley diode equation.
The series resistance (Rs) accounts for resistances that arise from
energetic barriers at interfaces and bulk resistances within layers.
Ideally, this is minimised to prevent efficiency losses due to increased
charge carrier recombination. This can be achieved by ensuring good
energy level alignment of the materials used in the solar cell.

DYE-SENSITIZED SOLAR CELL
Dye Sensitized solar cells (DSSC), also sometimes referred to as dye
sensitised cells (DSC), are a third generation photovoltaic (solar) cell
that converts any visible light into electrical energy.
This new class of advanced solar cell can be likened to artificial photosynthesis
due to the way in which it mimics nature absorption of light energy.
DSSC is a disruptive technology that can be used to produce electricity in a
wide range of light conditions, indoors and outdoors, enabling the user to
convert both artificial and natural light into energy to power a broad range of
electronic devices.
A dye-sensitized solar cell (DSSC, DSC, DYSC or Grätzel cell) is a low-
cost solar cell belonging to the group of thin film solar cells. It is based on
a semiconductor formed between a photo-sensitized anode and an electrolyte,
a photo electrochemical system. The modern version of a dye solar cell, also
known as the Grätzel cell, was originally co-invented in 1988 by Brian

O'Regan and Michael Grätzel at UC Berkeley and this work was later
developed by the afore mentioned scientists at the École Poly technique
Fédérale de Lausanne until the publication of the first high efficiency DSSC in
1991Michael Grätzel has been awarded the 2010 Millennium Technology
Prize for this invention
The DSSC has a number of attractive features; it is simple to make using
conventional roll-printing techniques, is semi-flexible and semi-transparent
which offers a variety of uses not applicable to glass-based systems, and most of
the materials used are low-cost. In practice it has proven difficult to eliminate a
number of expensive materials, notably platinum and ruthenium, and the liquid
electrolyte presents a serious challenge to making a cell suitable for use in all
weather. Although its conversion efficiency is less than the best thin-film cells,
in theory its price/performance ratio should be good enough to allow them to
compete with fossil fuel electrical generation by achieving grid parity.
Commercial applications, which were held up due to chemical stability
problems, are forecast in the European Union Photovoltaic Roadmap to
significantly contribute to renewable electricity generation by 2020.

Type of cell made at the EPFL by Grätzel and O'Regan
Operation of a Grätzel cell.
In the late 1960s it was discovered that illuminated organic dyes can generate
electricity at oxide electrodes in electrochemical cells. In an effort to understand
and simulate the primary processes in photosynthesis the phenomenon was
studied at the University of California at Berkeley with chlorophyll extracted
from spinach (bio-mimetic or bionic approach). On the basis of such
experiments electric power generation via the dye sensitization solar cell
(DSSC) principle was demonstrated and discussed in 1972. The instability of
the dye solar cell was identified as a main challenge. Its efficiency could, during
the following two decades, be improved by optimizing the porosity of the
electrode prepared from fine oxide powder, but the instability remained a
problem.
A modern DSSC is composed of a porous layer of titanium
dioxide nanoparticles, covered with a molecular dye that absorbs sunlight,
like the chlorophyll in green leaves. The titanium dioxide is immersed under
an electrolyte solution, above which is a platinum-based catalyst. As in a

conventional alkaline battery, an anode (the titanium dioxide) and a cathode (the
platinum) are placed on either side of a liquid conductor (the electrolyte).
Sunlight passes through the transparent electrode into the dye layer where it can
excite electrons that then flow into the titanium dioxide. The electrons flow
toward the transparent electrode where they are collected for powering a load.
After flowing through the external circuit, they are re-introduced into the cell on
a metal electrode on the back, flowing into the electrolyte. The electrolyte then
transports the electrons back to the dye molecules.
Dye-sensitized solar cells separate the two functions provided by silicon in a
traditional cell design. Normally the silicon acts as both the source of
photoelectrons, as well as providing the electric field to separate the charges and
create a current. In the dye-sensitized solar cell, the bulk of the semiconductor is
used solely for charge transport, the photoelectrons are provided from a
separate photosensitive dye. Charge separation occurs at the surfaces between
the dye, semiconductor and electrolyte.
The dye molecules are quite small (nanometer sized), so in order to capture a
reasonable amount of the incoming light the layer of dye molecules needs to be
made fairly thick, much thicker than the molecules themselves. To address this
problem, a nanomaterial is used as a scaffold to hold large numbers of the dye
molecules in a 3-D matrix, increasing the number of molecules for any given
surface area of cell. In existing designs, this scaffolding is provided by the
semiconductor material, which serves double-duty.
Construction
In the case of the original Grätzel and O'Regan design, the cell has 3 primary
parts. On top is a transparent anode made of fluoride-doped tin
dioxide (SnO2:F) deposited on the back of a (typically glass) plate.

On the back of this conductive plate is a thin layer of titanium dioxide (TiO2),
which forms into a highly porous structure with an extremely high surface area.
The (TiO2) is chemically bound by a process called sintering. TiO2only absorbs
a small fraction of the solar photons (those in the UV). The plate is then
immersed in a mixture of a photosensitive ruthenium-polypyridine dye (also
called molecular sensitizers) and a solvent. After soaking the film in the dye
solution, a thin layer of the dye is left covalently bonded to the surface of the
TiO2. The bond is either an ester, chelating, or bidentate bridging linkage.
A separate plate is then made with a thin layer of the iodide electrolyte spread
over a conductive sheet, typically platinum metal. The two plates are then
joined and sealed together to prevent the electrolyte from leaking. The
construction is simple enough that there are hobby kits available to hand-
construct them. Although they use a number of "advanced" materials, these are
inexpensive compared to the silicon needed for normal cells because they
require no expensive manufacturing steps. TiO2, for instance, is already widely
used as a paint base.
One of the efficient DSSCs devices uses ruthenium-based molecular dye,
e.g. [Ru(4,4'-dicarboxy-2,2'-bipyridine)2(NCS)2] (N3), that is bound to a
photoanode via carboxylate moieties. The photoanode consists of 12 μm thick
film of transparent 10–20 nm diameter TiO2 nanoparticles covered with a 4 μm
thick film of much larger (400 nm diameter) particles that scatter photons back
into the transparent film. The excited dye rapidly injects an electron into the
TiO2 after light absorption. The injected electron diffuses through the sintered
particle network to be collected at the front side transparent conducting oxide
(TCO) electrode, while the dye is regenerated via reduction by a redox shuttle,
I3/I, dissolved in a solution. Diffusion of the oxidized form of the shuttle to the
counter electrode completes the circuit

Mechanism of DSSCs
The main processes that occur in a DSSC
Step 1: The following primary steps convert photons(light) to current:
1. The incident photon is absorbed by Ru complex photosensitizers
adsorbed on the TiO2 surface.
2. The photosensitizers are excited from the ground state (S) to the excited
state (S∗). The excited electrons are injected into the conduction band of
the TiO2 electrode. This results in the oxidation of the photosensitizer
(S+
).
S +
hν →
S∗
(
1
)
(
2
)
4. The injected electrons in the conduction band of TiO2 are transported
between TiO2 nanoparticles with diffusion toward the back contact
(TCO). And the electrons finally reach the counter electrode through the
circuit.
5. The oxidized photosensitizer (S+
) accepts electrons from the I−
ion redox
mediator leading to regeneration of the ground state (S), and two I−
-Ions
are oxidized to elementary Iodine which reacts with I−
to the oxidized
state, I3
−
.
S+
+
e−
→
S
(
3
)

6. The oxidized redox mediator, I3
−
, diffuses toward the counter electrode
and then it is reduced to I−
ions.
I3
−
+ 2
e−
→ 3
I−
(
4
)
The efficiency of a DSSC depends on four energy levels of the component: the
excited state (approximately LUMO) and the ground state (HOMO) of the
photosensitizer, the Fermi level of the TiO2 electrode and the redox potential of
the mediator (I−
/I3
−
) in the electrolyte.
How does DSSC work?
1. The dye is the photoactive material of DSSC, and can produce electricity
once it is sensitized by light
2. The dye catches photons of incoming light (sunlight and ambient artificial
light) and uses their energy to excite electrons, behaving like chlorophyll in
photosynthesis
3. The dye injects this excited electron into the Titanum Dioxide (a white
pigment commonly found in white paint)
4. The electron is conducted away by nanocrystalline titanium dioxide (a
nano-scale crystallized form of the titanium dioxide).
5. A chemical electrolyte in the cell then closes the circuit so that the electrons
are returned back to the dye
6. It is the movement of these electrons that creates energy which can be
harvested into a rechargeable battery, super capacitor or another electrical
device.

Efficiency of DSSC
The efficiency of DSSC has continued to increase in the last 20 years, with a
confirmed record of 14.1% which was achieved by G24 Power advisory board
member Professor Michael Graetzel and his team..
These research-cells are produced in the laboratory with the knowledge and
advances in DSSC efficiencies due to be transferred into production cells at G24
Power in the near future.
The chart on the right is adapted from the National Renewable Energy
Laboratory Research Cell Efficiency Records chart.
How to measure cell efficiency of DSSC
The efficiency of DSSC and other solar cells for outdoor applications, such as
building integrated photovoltaics (BIPV), is typically measured under standard
test conditions (STC); Temperature 25Â°C, Irradiance 1000 W/mÂ² (1sun), Air
mass 1.5 (AM1.5) spectrum.
Under these test conditions a solar cell with 1mÂ² surface area producing 100
watts of power is measured at 10% power conversion efficiency (PCE).

Cell Efficiency Of DSSC Used Indoors
However, the calculation of DSSC efficiency for indoor applications differs.
The air mass (AM1.5) is not relevant for indoor PV operating conditions.
For example, if we used a realistic indoor light level and surface area for an
indoor application – Irradiance 100mW/cm2, with a 1cmÂ² surface area
producing 10mW then the PCE is measured at 10%.
Measuring solar performance by power density
Using power density can be a more tangible performance measurement of GCell
when used indoors. The method uses power output (e.g. microwatts) for a given
area (e.g. per cmÂ²) at a luminance level (e.g. 200lux).
Efficiency improvements of DSSC
The potential for improvement in the power conversion efficiency of DSSC is
one of the reasons it is regarded as a highly promising method for efficient and
economical conversion of light in to electrical energy.
DSSC improvements are buoyed by the development programs within large
chemical companies that enable new combinations of materials, chemical
formulation and cell structures to be considered. Areas for potential
improvements include dyes, electrolytes, redox couples, photoanodes and
tandem cell configurations.
A two level tandem DSSC embodiment could reach 46% efficiency
Professor Michael Graetzel, EPFL
Theoretical efficiency limit of DSSC
The theoretical photoelectric conversion efficiency (PCE) limit of the DSSC,
using a simple junction configuration, under standard test conditions (STC) is
32%Â according to Professor Michael Graetzel.
A two level tandem DSSC embodiment could reach 46% efficiency under the
same conditions. HigherÂ PCE’s reaching close to 40% can be achieved
indoors or in diffuse daylight that has a low infrared light content.

Nanoplant-like morphology
In DSSC, electrodes consisted of sintered semiconducting nanoparticles, mainly
TiO2 or ZnO. These nanoparticle DSSCs rely on trap-limited diffusion through
the semiconductor nanoparticles for the electron transport. This limits the
device efficiency since it is a slow transport mechanism. Recombination is more
likely to occur at longer wavelengths of radiation. Moreover, sintering of
nanoparticles requires a high temperature of about 450 °C, which restricts the
fabrication of these cells to robust, rigid solid substrates. It has been proven that
there is an increase in the efficiency of DSSC, if the sintered nanoparticle
electrode is replaced by a specially designed electrode possessing an exotic
'nanoplant-like' morphology.
Operation
Sunlight enters the cell through the transparent SnO2:F top contact, striking the
dye on the surface of the TiO2. Photons striking the dye with enough energy to
be absorbed create an excited state of the dye, from which an electron can be
"injected" directly into the conduction band of the TiO2. From there it moves
by diffusion (as a result of an electron concentration gradient) to the
clear anode on top.
Meanwhile, the dye molecule has lost an electron and the molecule will
decompose if another electron is not provided. The dye strips one from iodide in
electrolyte below the TiO2, oxidizing it into tri iodide. This reaction occurs quite
quickly compared to the time that it takes for the injected electron to recombine
with the oxidized dye molecule, preventing this recombination reaction that
would effectively short-circuit the solar cell.
The triiodide then recovers its missing electron by mechanically diffusing to the
bottom of the cell, where the counter electrode re-introduces the electrons after
flowing through the external circuit.
Efficiency
Several important measures are used to characterize solar cells. The most
obvious is the total amount of electrical power produced for a given amount of
solar power shining on the cell. Expressed as a percentage, this is known as
the solar conversion efficiency. Electrical power is the product of current and
voltage, so the maximum values for these measurements are important as well,
Jsc and Voc respectively. Finally, in order to understand the underlying physics,
the "quantum efficiency" is used to compare the chance that one photon (of a
particular energy) will create one electron.

In quantum efficiency terms, DSSCs are extremely efficient. Due to their
"depth" in the nanostructure there is a very high chance that a photon will be
absorbed, and the dyes are very effective at converting them to electrons. Most
of the small losses that do exist in DSSC's are due to conduction losses in the
TiO2 and the clear electrode, or optical losses in the front electrode. The overall
quantum efficiency for green light is about 90%, with the "lost" 10% being
largely accounted for by the optical losses in the top electrode. The quantum
efficiency of traditional designs vary, depending on their thickness, but are
about the same as the DSSC.
In theory, the maximum voltage generated by such a cell is simply the
difference between the (quasi-)Fermi level of the TiO2 and the redox
potential of the electrolyte, about 0.7 V under solar illumination conditions
(Voc). That is, if an illuminated DSSC is connected to a voltmeter in an "open
circuit", it would read about 0.7 V. In terms of voltage, DSSCs offer slightly
higher Voc than silicon, about 0.7 V compared to 0.6 V. This is a fairly small
difference, so real-world differences are dominated by current production, Jsc.
Although the dye is highly efficient at converting absorbed photons into free
electrons in the TiO2, only photons absorbed by the dye ultimately produce
current. The rate of photon absorption depends upon the absorption spectrum of
the sensitized TiO2 layer and upon the solar flux spectrum. The overlap between
these two spectra determines the maximum possible photocurrent. Typically
used dye molecules generally have poorer absorption in the red part of the
spectrum compared to silicon, which means that fewer of the photons in
sunlight are usable for current generation. These factors limit the current
generated by a DSSC, for comparison, a traditional silicon-based solar cell
offers about 35 mA/cm2
, whereas current DSSCs offer about 20 mA/cm2
.
Overall peak power conversion efficiency for current DSSCs is about
11%. Current record for prototypes lies at 15%.
Degradation
DSSCs degrade when exposed to ultraviolet radiation. In 2014 air infiltration of
the commonly-used amorphous Spiro-MeOTAD hole-transport layer was
identified as the primary cause of the degradation, rather than oxidation. The
damage could be avoided by the addition of an appropriate barrier.
The barrier layer may include UV stabilizers and/or UV
absorbing luminescent chromophores (which emit at longer wavelengths which
may be reabsorbed by the dye) and antioxidants to protect and improve the
efficiency of the cell.

Advantages
DSSCs are currently the most efficient third-generation[
(2005 Basic Research
Solar Energy Utilization 16) solar technology available. Other thin-film
technologies are typically between 5% and 13%, and traditional low-cost
commercial silicon panels operate between 14% and 17%. This makes DSSCs
attractive as a replacement for existing technologies in "low density"
applications like rooftop solar collectors, where the mechanical robustness and
light weight of the glass-less collector is a major advantage. They may not be as
attractive for large-scale deployments where higher-cost higher-efficiency cells
are more viable, but even small increases in the DSSC conversion efficiency
might make them suitable for some of these roles as well.
There is another area where DSSCs are particularly attractive. The process of
injecting an electron directly into the TiO2 is qualitatively different from that
occurring in a traditional cell, where the electron is "promoted" within the
original crystal. In theory, given low rates of production, the high-energy
electron in the silicon could re-combine with its own hole, giving off a photon
(or other form of energy) which does not result in current being generated.
Although this particular case may not be common, it is fairly easy for an
electron generated by another atom to combine with a hole left behind in a
previous photo excitation.
Disadvantages
The major disadvantage to the DSSC design is the use of the liquid electrolyte,
which has temperature stability problems. At low temperatures the electrolyte
can freeze, halting power production and potentially leading to physical
damage. Higher temperatures cause the liquid to expand, making sealing the
panels a serious problem. Another disadvantage is that costly ruthenium (dye),
platinum (catalyst) and conducting glass or plastic (contact) are needed to
produce a DSSC. A third major drawback is that the electrolyte solution
contains volatile organic compounds (or VOC's), solvents which must be
carefully sealed as they are hazardous to human health and the environment.
This, along with the fact that the solvents permeate plastics, has precluded
large-scale outdoor application and integration into flexible structure.
Replacing the liquid electrolyte with a solid has been a major ongoing field of
research. Recent experiments using solidified melted salts have shown some
promise, but currently suffer from higher degradation during continued
operation, and are not flexible.

FABRICATION OF DSSC
Transparent conducting oxide (TCO) coated glass substrates
Transparent conducting oxide(TCO) coated glass substrate are the basis of
DSSC onto which cell architecture stands. It can be prepared by using
sputtering or by low pressure chemical vapour deposition (LP-CVD). Sputtered
TCO coating very smooth and flat which does not meet the requirement of the
light scattering properties for the solar cells. To make it useful for DSSC
application chemical wet etching process is applied on sputtered surface so that
nanotexturing substrate can be achieved . TCO deposited can be achieved . TCO
deposited by LP-CVD Has advantages
i. It is simple and easy process
ii. It is up scalable up to 1m , with deposition rates over 2 mm/s.
iii. Oxide layer grown over transparent glass substrate or flexible
transparent substrate has a high nano texturing with crystallographic
preferential columnar growth.
During last three decades numerous types of TCOs were developed and studied
by the researchers but Fluorine –doped tin oxide (FTO) and Indium Tin
Oxide (ITO) based TCO are widely used for solar cell application because
they are considered the best compromise in terms of fabrication process ,
optical and electrical properties.

PHOTOANODE(WORKING ELECTRODE)
Nanocrystalline semiconductors oxide materials are used to prepare
photoanodes due to its exceptional stability against photo corrosion in photo
electrochemistry . Nanocrystalline semiconductors oxide materials is a large
band gap materials(>3 ev) .The oxide semiconductors materials are needed in
DSSC for the transparency of the working electrode for the large part of the
solar spectrum . Nanocrystalline titanium dioxide has wide applicability as
working electrodes for DSSC. Apart from nanocrystalline TiO2 , researchers
have used others semiconductors materials like ZnO , CdSe, CdS , WO3,
Fe2O3, SnO2, Nb2O5 and Ta2O5
TiO2 is cheap , easily available and non toxic material; It is employed as white
pigment in paints and tooth pastes. Particle sizes of Tio2 monitor electron
transport along with the TiO2 networks in terms of the mean free path. Larger
particle size provides both long travel distance and less collision chance with
the boundary . TiO2 particles with low transport resistance , high recombination
resistance , and low chemical capacitance , should exhibit longest diffusion
length with an electrolyte.
Titanium dioxide, also known as titanium(IV) oxide or titania, is the
naturally occurring oxide of titanium, chemical formula TiO2
When used as a pigment, it is called titanium white, Pigment White 6 (PW6).
Generally, it is sourced from ilmenite, rutile and anatase. It has a wide range of
applications, including paint, sunscreen and food colouring.
Titanium dioxide occurs in nature as the well-known
minerals rutile, anatase and brookite. It is mainly sourced from ilmenite ore.
This is the most widespread form of titanium dioxide-bearing ore around the
world. Rutile is the next most abundant and contains around 98% titanium
dioxide in the ore.

PREPARATION OF PHOTOANODE
Transparent conducting oxide (TCO) coated glass /flexible substrate is the base
of DSSC onto which existence of SSC architecture formulated . Fluorine doped
tin Oxide (FTO) or tin doped indium oxide(ITO) generally developed over
glass/flexible substrate by using RF sputtering technique or ion beam deposition
technique or atomic layer deposition technique etc for preparation transparent
conducting oxide (TCO). Presently for the preparation of DSSC architecture ,
FTO substrate is preferred due to its better thermal stability (stable up to 500o
C)
with respect to another substrate like ITO or others .the resistance of FTO
substrate chosen DSSC architecture should be around (10-20Ω/cm2
) as this is
path of the the electrons to reach after travelling through TiO2 nanoparticle
networks in working electrode and in counter electrode. Along with the
conductivity, transparency of the substrate to be used as working electrodes is
also very important as light has to pass through this substrate to activate TiO2
Dye sensitized layer molecules which in turn generates photo-electrones.
CLEANING PROCESS OF FTO:-
Seven step cleaning process have been optimized in laboratory for substrate to
be used in DSSC cell architecture so to minimize the contaminant level as well
as enhances the adhesion of subsequent layer to be deposited over it are as
follows
1. Cutting of FTO glass substrate into desired size according to our
requirement
2. Dipping all substrate to the soft solution and stir it for half an hour gently
(to remove macro contaminants)

3. Dipping substrate in output environment after that it should be dipped in
alcoholic solution (eg. methanol, ethanol & propenol)(to remove acidic
contaminants)
4. 0.1 N HCL will be used to stirred for half an hour so that all bases
contaminants should be removed.
5. Drying it in vacuum pressure (vacuum pressure=15 mm Hg)
6. Ultrasonic cleaning for 10-15 min to remove micro contaminants.
7. Plasma cleaning : using heric plasma cleaner to ultrasonic the substrate.
Synthesis Of Nanoparticles to Used in Preparation Of Working
Electrodes(Photoanode)
There are three mainly methods:-
Sol-gel
All the reagents used were of analytical grade and no further purification was
done before use. The sol-gel synthesized TiO2 was obtained from Titanium (IV)
isopropoxide (TTIP) was dissolved in absolute ethanol and distilled water was
added to the solution in terms of a molar ratio of Ti: H2O=1:4. Nitric acid was
used to adjust the pH and for restrain the hydrolysis process of the solution. The
solution was vigorously stirred for 30 min in order to form sols. After aging for
24 hrs, the sols were transformed into gels. In order to obtain nanoparticles, the
gels were dried under 120o
C for 2 hr to evaporate water and organic material to
the maximum extent. Then the dry gel was sintered at 450 o
C for 2 hrs were
subsequently carried out to obtain desired TiO2 nano crystalline.
14 ml of Titanium Butoxide mixed with 40 ml of methanol with constant
stirring at room temperature for preparation of sol gel nc-Tio2 . The prepared
Tio2 gel was then dried at 80 o
C for 10 hours. The solid material obtained now
crushed into fine particles and calcinated at 450 o
C for 2 hours at a rate of 3 o
C

per minute. Crushed fine particles dissolved in 1-butanol by continuous stirring
for 24 hours so that screen printing paste prepared . This paste was used in
screen printing using screen of 100 mesh to develop photoanode .
Hydrothermal method
Analytical grade titanium tetrachloride was adopted as the source material and
sodium hydroxide as mineralizer. An aqueous solution of titanium was obtained
by mixing one molar stoichiometric ratio of TTIP in 50 ml of distilled water.
The solution 2-3 mol of NaOH with stirring at several minutes, resulting in a
white colloidal sol. The final volume was adjusted to 90 ml using distilled
water. Therefore, 90ml sol was transferred to a 100 ml Teflon lined auto clave
vessel. The sealed vessel was heated to 240 o
C for 12 hrs and the resultant
precipitate was dried at 450 o
C for 2 hrs to obtain TiO2 nanoparticles.
Solvothermal synthesis
It is generally defined as a chemical reaction taking place in a solvent at
temperatures above the boiling point and pressures above 1 bar. The medium
used in a solvothermal synthesis can be anything from water (hydrothermal) to
alcohol or any other organic or inorganic solvent . Nevertheless, the term
“hydrothermal” is generally used, in many reports, describing all types of
synthesis that occur in a closed vessel with controlled temperature and pressure.
In fact, the number of articles associated with hydrothermal synthesis is almost
nine times greater than for solvothermal synthesis

DEVELOPMENT OF BLOCKING LAYER(BL)
Blocking layer (BL) is a nanoporous TiO2 active layer coating on the
photoanode to provide high surface area to enhance dye loading and
absorption of incoming solar light which is essential for efficient
photon –to-electricity conversion . BL fight against one of the limiting
factors of the performances of a DSSC is the electron recombination
process that takes place at the FTO/electrolyte interface . Because of
the porous nature of the nanocrystalline TiO2 layer in fact , the FTO
surface cannot be insulated form the electrolyte. It has been optimized
that a thin dense BL of TiO2 prevent these efficiency losses by
inhibiting the contact between the FTO and the electrolyte . In
addition to TiO2 , other material such as ZnO , Nb2O5 and grapheme
oxide are also known to be effective as BL.
The compact TiO2 layer is used as BL as its higher density of the
compact layer, together with large contact area and improved
adherence between the TiO2 layer and FTO surface provides more
electron pathways from TiO2 to FTO for photo generated electrons,
which facilitates electron transfer and subsequently improves the
electron transfer efficiency.

The optimized procedure for making BL is as follows-
i. Preparation of solution of titania –Titanium (IV) butoxide was
used to prepare sol gel based nc-Titania and 14 ml of Titanium
butoxide mixed with 40 ml of methanol with constant stirring at
room temperature for preparation of sol gel nc- TiO2 .The
prepared TiO2 gel was then dried at 80 o
C for 10 hours . The
solid material obtained now crushed into fine particle and
calcinated at 450 o
C for 2 hours at a rate of 3 o
C per minute. 1
gm crushed fine particle was dissolved in 100 ml butanol for
preparing 1% (w/v) solution. This solution is treated as BL
solution.
ii. Plasma cleaned substrate now warmed at 50 o
C is now dipped
in this solution for 15 minute with continuous stirring for
blocking layer to be deposited .In some earlier cases BL was
developed by spin coating technique by spinning substrate after
dropping 2-3 droplet of BL solution at the rate of 3000 rpm for 1
minute. But spin coated BL film was less uniform and rebust.
iii. The masking tape is removed and the films are then sintered at
450 o
C for 1 hour using muffle furnace and thus BL of compact
TiO2 developed over the substrate.

SENSITIZERS
Sensitizers preparing natural dyes For all dyes methanol was used as the
extraction solvent. The extracted dyes were obtained by the following steps:
fresh fruit and vegetables were washed with distilled water. then cut into small
pieces, immersed in methanol at room temperature and left to macerate for a
day. This was then filtered using a vacuum pump and the filtrate was used as a
sensitizer. 2.2. Preparation of dye sensitized solar cells FTO conductive glass
sheets were first ultrasonically cleaned using a mixture containing 10 ml of
ethanol, 10 ml of propanol and 10 ml of distilled water for 30 minutes. Titanium
dioxide (TiO2) paste was prepared using Degussa P-25, whose average TiO2
particle size was 26 nm. P-25 (0.14 g) was set in a shaker, and HNO3 (0.6 ml)
was added into the shaker. Later, polyethylene glycol (PEG) was added into it.
The obtained TiO2 paste was coated using Doctor Blade method onto the FTO
clean glass substrate. The obtained substrate was set in an electric oven for
annealing at 450 C for 30 min in order to eliminate water vapour and the
polymer binder. This formed the pre-prepared TiO2 photoelectrode which is to
be sensitized. Sensitization was done by immersing this electrode in a methanol
solution containing the extracted dye for 1 day in dark.
DYE SENSITIZERS
In a DSSC, a dye sensitizer plays a very important role in generating the photo-
induced electrons and injecting them into the conduction band of the
TiO2 semiconductor.
An ideal dye sensitizer for DSSCs should meet several criteria of

(1) absorbing solar light below a threshold wavelength of ∼920 nm,
(2) being strongly grafted to the TiO2 surface,
(3) smoothly injecting electrons to the conduction band of TiO2 semiconductor,
(4) having suitable redox potential that can be rapidly regenerated through
the redox couple (I−
/I3
−
) in the electrolyte, and
(5) being stable under solar light illumination and continuous light soaking.
According to these criteria, the efficient dye sensitizers can be simply divided
into two groups:
(1) METAL ORGANIC SENSITIZER DYES
It is a metal based sensitizers exhibit some important limits i.e. expensive
synthesis process, relatively low molar extinction in the visible region , limited
availability of precursors and waste disposal issue. Between metal organic yes,
the most use ones are ruthenium or osmium derivatives , which are
characterized by prolonged long term stability . In particular , the polypyridyl
ruthenium sensitizer family allows fabricating DSSCs with high conversion
efficiency values
N-3 N-719 Z-907
C26H16N6O8RuS2 C58H86N8O8RuS2 C42H52N6O4RuS2
Mol Wt: 705.64 Mol Wt: 1188.55 Mol Wt: 870.10
Figure . Ruthenium-based N-3, N-719 and Z-907 dyes.

(2) METAL-FREE ORGANIC DYES
Metal free organic dyes could present several advantage , being obtainable with
simple , fast and cost effective synthetic approach and characterized by high
molar extinction coefficients . in comparison to the metal organic sensitizers ,
however , organic dyes exhibit dyes, lower conversion efficiencies, due to the
formation of dye aggregates on the semiconductor surface and to their narrow
light absorption bands in the visible region. Different families of organic
sensitizers have been researched in the last decade and the conversion efficiency
of these cell has become comparable to the one of cells based on the poly
pyridyl ruthenium
Rose Bengal Xylenol orange
.
C20H2Cl4I4Na2O5 Chemical formula: C31H32N2O13S
Molecular weight 1017.64
PREPARATION OF PHOTOCATHODE(COUNTER ELECTRODE)
platinum (Pt) counter electrodes were fabricated by spreading a drop of 5 mM
chloroplatinic acid hexahydrate (H2PtCl6.6H2O) in isopropyl alcohol onto the
FTO surface followed by heating it at 450C for 30 min. Pt electrode was used
because it is most resistant to corrosive attacks by the redox couple (I/I3) and
facilitates a reversible redox reaction to occur. Since only very small quantity of
Pt is been used in making the counter electrode, this still reduces its cost at the

same time maintaining its transparency for photon entry. The dye sensitized
TiO2 photoelectrode and the Pt counter electrode was assembled to form a
sandwich solar cell.
For this , Pt coated FTO as counter electrode material which was drop casting of
0.5 M H2PtCl6 in methanol solution on FTO using water bath evaporation
technique. It was allowed to dry on water bath for few minutes and after that it
is sintered at 450 o
C for 1 hr in muffle furnace.
ELECTROLYTES
The electrolyte is a key component of dye-sensitized solar cells(DSSC) which
acts as charge carrier collecting electrons at the cathode and transporting the
electrons back to the dye module .The most commonly used liquid electrolyte ,
namely iodide/ triiodide (I-/I3-)
Preparation of electrolyte
Two types of electrolytes were used for the preparation of DSSC which is as
follows-
1) Liquid Electrolyte - for liquid electrolyte 0.05 M KI and 0.05 M I2 in 10
ml acetonitrile solvent with continuous stirring for 2 hours for making of
homogeneous solution. Now 1 gm TiO2 (Degussa P25 powder) is added
to it and at last 0.5 M 4-tertbutylpyridine is added to the solution for
formation of I-/I3- iodide tri iodide redox couple. Leakage problem are

very crucial in using this electrolyte .The above mentioned concentrations
are optimize for our set of experiments.
2) Quasi Solid State Electrolyte- A polymeric electrolyte consisting of
iodide /triiodide redox was prepared by the procedure reported elsewhere
. In this process , a mixture of Gamma butyro lactone (GBL) & n-methyl
pyrrolidone (NMP) was taken and KI (0.5 M) & I2 (0.1 M) was added
into it. Further, a thin sheet of poly vinyl butraldyhyde(PVB) was
immersed into it for two hours and then taken out for the use as
electrolyte.
After that , if prepared paste seems like as the toothpaste then it
is pasted on working electrode by using screen printer .Blocking
Layer should be uniform on working electrode by using the
screen printing technique .Then it is dried at room temperature
for 10 hours. Now, working electrode dipped in the dyes solution
for 24 hours at room temperature .Working electrode dried at
room temperature after dying. Electrolyte solution is pasted on
working electrode and assembling with counter electrode .Small
area of both electrode are left open for contact purposes. Hence
DSSC cell is prepared . Now ready for experimental values.

RESULT FROM THE DSSC SOLAR CELL
Quasi –solid state electrolyte used.
Xylenol orange Dye is used.
Output Voltage = 0.33 V Output Current = 100 µA
Semiconductor Parameter analyser
Curve of J-V for DSSC :-
Voltage(V) Current(mA)
-1 -15.9
-0.9 -11.8
-0.8 -7.975
-0.7 -4.543
-0.6 -1.9
-0.5 -0.61
-0.4 -0.228
-0.3 -0.16
-0.2 -0.132
-0.1 0.094
0 -0.102
0.1 -0.086
0.2 -0.0409
0.3 0.21
0.4 0.247
0.5 0.83
0.6 2.552
0.7 5.764
0.8 9.676
0.9 14
1 16

IV Quadrant J-V curve:-
-0.12
-0.07
-0.02
0.03
0.08
0 0.05 0.1 0.15 0.2 0.25
Voltage(Volts)
Current(mA)
Current(mA)
Current(mA)

Fill factor:-
FF= (Maxi. Area of J-V curve) / (Total area of J-V curve)
Vmax.=0.075 V I max.=0.15 mA
Voc=0.22 V Isc=0.11 mA
Now,
FF = Vmax I max. / Voc Isc
FF= (0.075 V* 0.15 mA )/ (0.22 V *0.11mA)
FF= 0.4648
Efficiency:-
Ê= (FF * Voc *Isc ) / Pin (watt/ m2
) * 100
Pin= 600 watt/ m2
Ê= (0.4648*0.22 V *0.11mA) / 600 *100
Ê= 0.00187 %

DC MOBILE CHARGER FOR DSSC
Mobile charging can be done by DSSC solar cell .It can obtained by simple
circuit which is shown below:-
Material used:-
i. IN 4007 Diode
ii. LM 7805 IC
iii. 100 µF, 25 V capacitor
iv. Connecting wires
v. Charging Plug

CONCLUSION
Research training at Defence laboratory, Jodhpur provides me the practical as
pact of the theory knowledge . This training developed a good understanding
between theoretical and practical knowledge. During training period I learned a
lot of things which will helpful in my future. I have made DSSC cell and their
applications. DSSC has wide field for research in the future.
And from the study of renewable sources we can conclude that there is a large
scope in them and government is also taking initiatives for the use of renewable
sources.
Indeed, The research training at DLJ has been a very good learning experience
for me. The knowledge of theoretical subject is not enough for any engineering
stream. One has to have the practical knowledge to remove the gap between the
actual and expected performances.

REFERENCES
1) Narottam Prasad , Manish kumar, Amit K. Sadh, and M. S.
ROY IEEE JOURNAL OF PHOTOVOLTAICS , 2012, 312-
319
2) M. Gratzel , Acc. Chem. Res. 2009 , 42, 1788
3) B. O’Regan , M. Gratzel , Nature 353 (1991) 737
4) DSSC Materials Sigma Aldrich
5) GD Sharma , SK Sharma , R kumar, MS Roy solar energy
materials and solar cells 3006,90(13), 1888-1904
6) W. Shockley and H.J. Queisser , J. Appl. Phys. 1961, 32, 510.
7) https://en.wikipedia.org/wiki/Xylenol_orange
8) “Dye solar cell assembly” instructions solaronix
9) www.sciencrdirect.com Science direct
10) Dye sensitized solar cell Dyesol limited
11) http://www.gamry.com
12) http://gcell.com
13) http://iopscience.iop.org
14) http://www.ncbi.nlm.gov

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