Graetzel Solar Cell

Michael Grätzel 11 May 1944, Dorfchemnitz, Germany. He is a professor at the École Polytechnique Fédérale de Lausanne where he directs the Laboratory of Photonics and Interfaces. He discovered a new type of solar cell based on dye sensitized mesoscopic oxide particles and pioneered the use of nanomaterials in lithium ion batteries.

A solar cell uses light from the sun to produce electricity A solar cell uses light from the sun to produce electricity. Using simple materials we can make a type of solar cell called a dye-sensitised solar cell. This type of cell is cheaper than other solar cells, and is now produced commercially.  It is based on a semiconductor formed between a photo-sensitized anode and an electrolyte, a photoelectrochemical system

Making a solar cell To make a solar cell we will prepare two halves of the cell and then put them together. One half of the cell is called a ‘working electrode’ and the other half is called a ‘counter electrode.’

Materials General Materials Scotch Tape Beaker of water Paper towels Small beaker 2B pencil Tweezers Spare beaker 2 paper clips Torch Multimeter 2 crocodile clip leads Scalpel

Materials Chemicals and speciality materials: 2 FTO slides Titania paste Blueberries Peel of eggplants Hibiscus flowers Alcohol Iodine solution The materials we are going to use today are not dangerous.

Step 1: Checking which side of the glass is conducting The electrodes are prepared using special glass. The glass is coated on one side with Titania paste, a material which conducts electricity. Therefore, only one side of the glass conducts electricity. Remember to hold the glass by the edges as much as possible so that you don’t damage the surface of the glass.

1. Set the multi-meter to 2000 Ω. 2. Touch each side of the transparent glass with both ends of the two probes connected to the multi-meter and decide which side of the glass is conducting. If the value stayed at 1 the side of the glass is not conducting.

Step 2: Coating glass with Titania paste Now we should cover a side of the other glass with the Titania paste using a spatula, then put the glass on a hot plate to let dry the paste. However this is a very time demanding operation and we will use pre-coated glass (the white one)

Step 3: The glass in the beaker We have beakers with different kind of compounds: 1: Alcohol + Blueberries 2: Alcohol + Peel of eggplants 3: Alcohol + Hibiscus flowers 4: Mixture of 1,2,3 Now put the white glass into one beaker. The darker the compound is, the more light the cell will absorb.

Step 4: Sealing with scotch tape Using scotch tape and a scalpel make sure to seal sides of the transparent glass. Make sure to cover with scotch tape the conducting side.

Step 5: Recover the glass in the beaker Using a tweezer recover the white glass into the beaker

Step 6: The composition Put the white glass on a paper towel with the white side up. Put the conducting side of the transparent glass on it. Leave a space at each side and lock them using a clip-

Step 7: Adding the iodine solution It’s time to add the iodine solution. Allow the iodine solution to penetrate completely between the glass slides. This operation may last some minutes, don’t try to quicken it by adding more solution.

Step 8: It’s time to check! Now our solar cell is ready. We have to try it by using the multimeter. Connect crocodile clips to the solar cell and to the multimeter. Set the multimeter to 2V

It works! If everything’s okay then our cell will work properly. Try to light it up with different kind of lights: 1: Solar Light 2: Yellow Torch Light 3: White Torch Light (as the one of mobile phones) The solar cell will react in different ways. If you try to cover it with a paper towel you will see a decrease of values on the multimeter.

By connnecting more solar cells together you will be able to power small electrical devices, such as a calculator. Solar cells may last some days or even months, it depends on how well they are made and on how they are preserved.