The cell that we are going to learn how to make today is for educational purposes only and not for producing electricity on a large scale. Our solar cell will convert solar energy into electrical energy.
To make the cell work, we need a material that produces the photovoltaic effect, usually silicon. But for this project, we will be using cuprous oxide (Cu2O), a semiconductor used in the manufacture of diodes before silicon.
This solar cell is not going to light a house, it is a simple project to learn how a photovoltaic solar cell works. For this reason, we will use cuprous oxide and not silicon or germanium, which is the material used in the commercial manufacture of solar cells, with much higher efficiency.
The operation is simple, solar energy gives enough energy to the electrons of the last layer of the oxide, so that they become free electrons. These pass through the salt water which is our electrolyte and reach the clean plate, returning through the wires to the burnt plate. The greater the radiation, the greater the quantity of free electrons that we will obtain and therefore the current will be greater.
Materials to make a homemade photovoltaic solar cell.
- Copper foil (the project uses a 30 x 30 cm x 1/16 ″ foil to make three pairs of 10 x 10 cm cells).
- Electric burner.
- Cables with alligator or alligator clips.
- Plastic bottle (preferably large to prevent the plates from coming into contact).
- Table salt.
- The water.
- Ammeter / multimeter.
We will start by washing our hands so as not to transfer fat into the cell when we work with it.
We cut the copper foil so that its area can be fully heated by the burner you use (We work with sheets of 10 x 10 cm). Heat the foil on the stove for about half an hour. Wash the film beforehand to avoid traces of grease.
On heating, the copper foil will take on a color similar to that in the figure above. After which, a black layer will form, which is cuprous oxide. It is necessary to achieve that a good oxide layer is formed, in order to be able to work (with half an hour of heating this should be sufficient).
Now let the leaf cool for about 20 minutes. You will notice that flakes will have formed which you can separate by tapping lightly on the sheet. Do not completely clean the blade or the experience will be ruined.
Finally, cut out a plate the same size as the previous one. Assemble the following assembly, connect each plate with a crocodile, fill a container with salt water (it is better if it is preheated or if you add lemon to the water) and place the plates face to face, trying to ” prevent them from coming into contact.
You should check with the multimeter, that the unburnt plate is the positive pole and the burnt one is the negative pole. The current will depend on the surface of the plate and the solar radiation at the time. You can make combinations of this cell, in series or in parallel to get higher voltages or currents.
Some videos in case of doubt: