From the little research I did, they seem to be similar to photons but not quite there. I ran into it learning about solar panel tech. Basically, photons hitting the silicone in the panel need a bit of help from phonons, and those new perovskite cells don’t. What are phonons and how do they work when it comes to solar panels?
In: 3
To explain phonons it is useful to first talk about what a photon is. We typically think of photons as particles of light, little packets or quanta of electromagnetic oscillations.
Phonons are a similar idea, but instead of being quanta of electromagnetic oscillations they are a quanta of vibration. When you have a solid material and you hit one of the particles in it, the forces around it will cause it to vibrate, this vibration travels throughout the solid in a similar way to a particle, this is a phonon.
Now these aren’t ‘real’ particles, you can’t isolate a phonon on its own. They are quasi-particles resulting from the behaviour of many particles acting together in such a way that they behave as if they are passing a particle between them.
Think of a chunk of crystalline solid. The atoms inside this solid is very ordered, and as such, if you create a tiny vibration on the solid, it will propagate as waves. This vibration will have different wavelengths and energies associated with it. In quantum mechanics, the energy of waves are discrete and a phonon is just a fancy way of describing one unit of energy of a particular vibration. At room temperature, you will have many of these waves or phonons in a crystalline solid.
Solar cells are made of semiconductors. In a semiconductor, a photon (a discrete unit of energy of electromagnetic radiation from the sun) will be absorbed if it meets a certain energy threshold due to the property of the material. Once it’s absorbed, it gets converted to electricity. However if a photon does not meet that threshold, then it can be absorbed in combination with a phonon with enough energy to surpass the threshold. The latter happens at a lower rate. All of this energy is transferred to an electron for electrical conduction.
Latest Answers