DIY Cuprous Oxide Solar Cells

Ridah Arshad


Ever wondered if it was possible to harness the energy of the sun from the comfort of your own home? Turns out, it is possible to create your own solar cell and witness the photoelectric phenomenon for yourself, even if it may not be a 20% efficient SunPower solar panel.


Typically, solar cells rely on the photovoltaic effect, which involves the dislodging of electrons by photons within p-n junctions. The solar cells we’ll be making today however, are slightly different. Rather than photovoltaic cells, they are photoelectrochemical cells. The critical component of these cells is the semiconducting material that forms one electrode of the battery.


Typically, solar cells rely on the photovoltaic effect, which involves the dislodging of electrons by photons within p-n junctions. The solar cells we’ll be making today however, are slightly different. Rather than photovoltaic cells, they are photoelectrochemical cells. The critical component of these cells is the semiconducting material that forms one electrode of the battery.

  • When sunlight strikes this electrode, electron-hole pairs are generated through photons with enough energy to eject the electrons.

  • Electrons on the valence band get excited to the conduction band, leaving a hole behind.

  • Cuprous oxide is a p-type semiconductor, thus ejected electrons are used to reduce H+ into H2 at this electrode, while at the counter, metallic electrode, water is oxidized by holes into O2 and H+.

  • Electrons are pushed towards the electrolyte to generate a cathodic photocurrent.

  • This process is referred to as water splitting - relies on electrons and holes splitting water into its elemental components through oxidation and reduction reactions.

 
STEPS

1. First, prepare your electrodes. Each plate should ideally be about 10-15 cm in length and ½ inch -1 inch in width. Then, both plates of copper need to be thoroughly cleaned. Warm water and/or a microfiber cloth work well, since the electrodes have not been previously used.


2. Place one of the copper plates on a hot plate. This will allow us to create an oxide layer on both surfaces of the plate. A gas stove works as well, however the oxidation will occur less evenly.


3. Cook for around 10 mins. You will see many different colours forming on the surface. This is a good sign! Turn off the heat when a blackish tint forms.


4. Leave the sheet of copper on the burner while it cools.


5. Prepare an electrolyte solution using a 1:3 ratio of salt to water in a container, and place both electrodes inside on opposite ends of the container.


6. Connect the alligator clips to each electrode. The cuprous oxide electrode should be connected to the positive terminal of the multimeter and the copper electrode should connect to the negative terminal of the multimeter.


7. Finally, place your battery into sunlight. If you’re like me, this will be a rare occurrence of getting some sunshine, so take a moment to take it in before returning to hibernation.


8. Don’t forget to set your multimeter to microamps! A small current should be observed on the device.

 

Congrats! You have now made a homemade solar cell and are well on your way to becoming a renewable energy maestro! Unfortunately, powering any device with this level of current is not possible, but you should still be proud of the electricity you’ve converted, no matter how small.