Dye sensitized solar cells (DSSC)

1. Dye Sensitized
Solar Cell (DSSC)
Kaavya B
II MSC Physics

2. Outline
•What is DSSC?
•Principle
•Construction
•Components explanation
•Working
•Advantages
•Disadvantages
•Facts

3. What is DSSC?
•Dye sensitized solar cells also referred as
dye sensitized cells are an efficient type of
thin – film photovoltaic cell.
•These cells convert any visible light into
electrical energy.
•It was invented by Michael Gratzel in
1988.

4. Principle
•The mechanism of dye solar cells is based
on the photo-electrochemical processes.

5. Construction
•Transparent & Conductive substrate
•Working electrode
•Dye (sensitizer)
•Electrolyte
•Counter electrode
are the five key components for a DSSC.

6. DSSC Structure
DSSC consists of two electrodes, working
electrode made up of nano crystalline TiO2
soaked with a dye and sealed to counter
electrode (Pt) soaked with a thin layer of
electrolyte with the help of a hot melt tape
to prevent the leakage of the electrolyte.

7. 1. Substrate
•DSSC’s are constructed with 2 sheets of
conductive transparent films which help
a substrate for the deposition of the
semiconductor and catalyst acting also as
current collectors.
•It must have 80% of transparency .
•It must have high electrical conductivity.

8. Substrate
•FTO or ITO are usually applied as a
conductive substrate in DSSC.
•The conductive film must have a low
electric resistance of 10 -20 Ω per square
at room temperature.

9. 2. Working Electrode
•It is prepared by depositing a thin layer of
oxide semiconducting materials such as
TiO2 on a transparent conducting glass
plate made of FTO or ITO.
•After soaking the film within the dye
solution, the dye gets covalently bonded
to the TiO2 surface.

10. Working Electrode
•Due to the highly porous structure and
the large surface area of the electrode,
high number of dye molecules get
attached on the nano crystalline TiO2
surface, and thus light absorption at the
semiconductor surface increases.

11. 3. Photosensitizer or Dye
•It is responsible for the maximum
absorption of the incident light.
•They should be able to absorb light at all
wavelengths below 920 nm.
•Most commonly used dyes are ruthenium
based, organic dyes and natural dyes.

12. Dye
•The dye should be luminescent.
•To avoid the aggregation of the dye over
the TiO2 surface co – absorbents like
phosphoric acid, carboxylic acid group
etc., were inserted between the dye and
TiO2

13. 4. Electrolyte
•It facilitates the transport of charge
between the working electrode and
counter electrode.
•The ideal electrolyte solvent must have
low viscosity, negligible vapor pressure,
high boiling point and high dielectric
properties.

14. Electrolyte
•The most common electrolyte is a liquid
electrolyte containing the redox couple
iodide/ triiodide.
•The chosen electrolyte should be non –
corrosive with DSSC components.
•It should be able to permit fast diffusion
of charge carriers.

15. 5. Counter Electrode
•It is prepared by using platinum or
carbon.
•It catalyzes the reduction of I- /I-
3liquid
electrolyte.
•Platinum is used as a counter electrode
because of its higher efficiencies.

16. Working of DSSC
•The working principle of DSSC involves
light absorption, charge separation and
charge collection.
•Under sunlight illumination, the dyes will
absorb photons (light) and these photons
become excited.
S hν S*

17. Working
•The absorbed dye molecules will inject
electrons into the TiO2 working electrode
and thus become oxidized.
S* S+ + e-
•Charge separation is attained across the
semiconductor interface where an electron
is located in the TiO and a hole is located

18. Working
in the oxidized dye molecule.
•The electrons will then percolate through
the porous network of TiO2 and
eventually reach the back contact of the
working electrode where charge collector
and charge extraction occur.

19. Working
•The extracted charge can perform
electrical work in the external circuit and
eventually return to the counter electrode
where reduction of the redox mediator
takes place.
•The liquid redox electrolyte completes the
circuit by reducing the oxidized dye.

20. Image

21. Advantages
•Optimized performance
•Higher temperature performance
•Ecologically friendly
•Higher efficiency

22. Disadvantages
•Platinum and ruthenium are limited
resource and are expensive.
•Co – sensitizer is required to optimize the
performance of DSSC.

23. Facts !!!
•DSSC technology arose from the concept
of “artificial photosynthesis”.
•It replicates the ability of plants to turn
sunlight into useful energy, where in
chlorophyll is replaced by a light
absorbing dye in case of DSSC.