How are Solar Cells made?
Silicon is still the most popular solar-cell material for commercial applications because it is so readily abundant. To be useful in solar cells, it must be refined to 99.9999% purity. The molecular structure of single-cell silicon is uniform, which is ideal for efficient electron transfer. To make an effective PV cell, silicon is “doped” to make it n-type or p-type. A second, much cheaper form is semicrystalline silicon which consists of several smaller crystals known as “grains,” which introduce “grain boundaries” to the solid. These boundaries impede the flow of electrons and encourage them to recombine with holes. There is a trade-off between the cost and the power reduction. To create the different semiconductor layers, the silicon is “doped”, either with an element that has an extra electron or is lacking an electron. Putting the n and p layer together creates the junction that causes the material to generate electricity when in a light source. There are three technologies availa
