S.VASANTH VICTOR

(SENGUNTHAR COLLEGE OF ENGINEERING)

PRESENTED BY,

DYE SENSITIZED SOLAR CELLS

INTRODUCTION• Dye-sensitized solar cell (DSSC) is the third

generation of solar cell which comprises of semiconductor electrode, counter electrode and electrolyte.

• It utilizes the advantage of the wide band gap semiconductor that sensitized to the light.

• Low cost solar cells • Invented by Brian o’ Regan and Michael Gratzel

at UC Berkley• Conversion efficiency lower then other thin

film cells.• Price/performance ratio is better.

2

COMPONENTS The DSSC device consists of 4 components:

Semiconducting electrode• n-type TiO2 and p-type NiO

Dye-sensitizer• Light harvesting and electronic transition

Redox mediator• I- / I3

- or CoII / CoIII complexes

Counter electrode• Carbon or Pt

3

DYE SENSITIZED SOLAR CELLS

4

WORKING PRINCIPLE• Dye Sensitizers absorb the Sunlight, which

results in electron injection into conduction band of Oxide (charge separation takes place at interface of oxide and dye).

• 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.

5

WORKING PRINCIPLE• Original state of Dye is subsequently restored by

electron donation from the electrolyte(Redox iodide/Triodide).

• Iodide is regenerated in turn by the reduction of triiodide at the counter electrode the circuit being completed via electron migration through the external load.

• Redox regeneration at the counter-electrode (oxidation).

• Dye regeneration reaction (reduction).

6

WORKING PRINCIPLE• The voltage generated under illumination

corresponds to the difference between the Fermi level of the electron in the solid and the redox potential of the electrolyte.

• Overall the device generates electric power from light without suffering any permanent chemical transformation

7

ENERGY LEVEL DIAGRAM

8

TiO2

9

• TiO2 acts as an absorber of Ultraviolet (UV) energy, but is virtually transparent to visible light.

• It is widely available material.• It is Biocompatible material.• It is Non toxic.

DYE SENSITIZER• Absorb all light below a threshold wavelength of about 920

nm.

• Contain attachment such as Carboxylate or Phosphonate group for better attachment with semiconductor oxide.

• Quantum yield of unity for injection of electrons in Semiconductor oxide.

10

DYE SENSITIZER

11

EFFICIENCY• Electrical power generated =Isc * Voc

• Voc ~ 0.7 (greater then normal Silicon cells)• Isc for DSSC ~ 20 mA/cm2

an• Silcon cells ~ 35 mA/cm2 • Peak conversion Efficiency achieved ~ 11 %• Max . Peak conversion Efficiency ~ 15 %

12

CONCLUSION

13

• DSSCs show the most promising future due to their independence, environmentally friendly, low maintenance, and low cost .

• A solar energy system can be installed in any location without a connection to a power grid.

• The initial investment is expensive. Once the use of electricity reaches to a certain point, the solar energy is free.

• After installation, there is no recurring cost and it can be used for a long time.

Queries…?

14

15

THANK YOU