DYE SENSITIZED SOLAR CELLS

BASICS OF DYE SENSITIZED
SOLAR CELLS
Presented by
R.THIRUMOORTHY
ASSISTANT PROFESSOR
DEPT. OF EEE
PACET
PACET

PACET
COURSE CONTENTS
•Renewable Energy sources
•Solar photovoltaic cell
•Types of Solar photovoltaic cell
•Dye sensitized Solar cells (DSSC)
•How does DSSC work?
•Construction of DSSC
•Applications
•Summary

PACET
RENEWABLE ENERGY SOURCES IN INDIA
•4th Largest wind power capacity in the world.
•In 2017-18, wind power installed capacity stands at 34 GW.
•6th Largest solar power capacity in the world.
•Solar Energy capacity increased to 22 GW in 2017-18.
•World’s largest ground based solar power and world’s largest rooftop solar plant are
both in India.
•Biomass power includes installations from biomass combustion, biomass gasification
and bagasse co-generation, for which capacity stands at 8.1 GW, as on November
2017.
•In accordance with the COP21 Paris accords, the Government of India has set a target
of adding 175 GW of renewable power in the country by 2022, which will offer massive
investment opportunities across the value chain.
•Total Renewable Energy Capacity in 2017-18 stands at 70 GW.

PACET
TYPES OF SOLAR PHOTOVOLTAIC CELLS

PACET
DYE-SENSITIZED SOLAR CELLS
• A dye sensitized solar cell is a new kind of relatively low cost solar cell with great potential as
its materials are considerably cheaper and it is simple to make.
• Michael Gratzel and Brian O’Regan invented ‘Dye-Sensitized Solar Cells’, also called “GRATZEL
CELLS” in 2005.
• The first cells were only capable of using light at the ultraviolet and blue end of the
spectrum.
• The most effective dyes are simply known as “BLACK DYES” due to their very dark colours.

PACET
HOW DOES DSSC WORK?
•The dye is the photoactive material of DSSC, and can produce electricity once
it is sensitized by light
•The dye catches photons of incoming light (sunlight and ambient artificial light)
and uses their energy to excite electrons, behaving like chlorophyll in
photosynthesis
•The dye injects this excited electron into the Titanum Dioxide (a white pigment
commonly found in white paint)
•The electron is conducted away by nanocrystalline titanium dioxide (a nano-
scale crystallized form of the titanium dioxide).
•A chemical electrolyte in the cell then closes the circuit so that the electrons
are returned back to the dye
•It is the movement of these electrons that creates energy which can be
harvested into a rechargeable battery, super capacitor or another electrical
device.

PACET
STEP 1: The dye molecule is initially in its ground state (S). The semiconductor material of the
anode is at this energy level (near the valence band) non-conductive.
When light shines on the cell, dye molecules get excited from their ground state to a higher
energy state (S*).
Eq. 1
The excited dye molecule has now a higher energy content and overcomes the band gap of the
semiconductor.
STEP 2: The excited dye molecule (S*) is oxidized and an electron is injected into the
conduction band of the semiconductor. Electrons can now move freely as the semiconductor is
conductive at this energy level.
Eq. 2
Electrons are then transported to the current collector of the anode via diffusion processes. An
electrical load can be powered if connected.
STEP 3: The oxidized dye molecule (S+) is again regenerated by electron donation from the
iodide in the electrolyte (see equation 3).
Eq. 3
STEP 4: In return, iodide is regenerated by reduction of tri iodide on the cathode .
Eq.4

DYE SENSITIZED SOLAR CELLS

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