| In this article, we are going to look at how solar | | | | quite know where to fit in. As a result, it sort of "lingers |
| photovoltaic cells (PV) works. However, rather than | | | | uncomfortably" waiting for something to happen. |
| taking a dull, textbook approach, we are going to make | | | | Now, we can use these two types of "doped" silicon |
| the whole process fun by doing some practical kitchen | | | | to make semiconducting devices, in this case |
| experiments that mimic the process that happens in | | | | "photovoltaic cells." |
| solar cell factories all around the world. | | | | A photovoltaic solar cell is a bit like a sandwich. It is |
| First of all, let's cover a little bit of the theory. | | | | made from layers of different types of silicon. |
| Ordinary silicon forms into a regular crystalline structure. | | | | Starting from the base, we have a large contact. Then |
| Generally, silicon atoms are aligned into a regular array. | | | | on top of this we have a layer of p-type silicon, a |
| To make silicon "semiconducting," we can take a little | | | | junction called the space charge region where the |
| bit of another chemical, in this case boron, and | | | | magic occurs, and a slice of n-type silicon on top. |
| introduce it to the silicon. Where there is a boron atom, | | | | On top of all this is layered a grid electrode, which |
| there is also a missing electron. This creates a "hole" in | | | | does the job of making the other contact. Now, |
| the outer shell of the boron atoms and its neighboring | | | | photons from the sun hit our solar cell, and in doing so |
| silicon atom. | | | | "spare" negatively charged electrons, are "knocked" |
| If we add a little bit of phosphorus to our silicon, we get | | | | across the boundary between p- and n-silicon, which |
| the opposite effect, a "spare" electron, which doesn't | | | | causes a flow of electrons around the circuit. |