The first commercially available solar cells were made from monocrystalline silicon, which is an extremely pure form of silicon. To produce these, a seed crystal is pulled out of a mass of molten silicon creating a cylindrical ingot with a single, continuous, crystal lattice structure. This crystal is then mechanically sawn into thin. Instead of a single uniform crystal structure, polycrystalline (or multicrystalline) cells contain many small grains of crystals (see figure 2). They can be made by simply casting a cube-shaped ingot from molten silicon,. Although crystalline PV cells dominate the market, cells can also be made from thin films—making them much more flexible and durable. One type of thin film PV cell is amorphous silicon (a-Si). Electricity can be produced through the interaction of light on many other materials as well. Perovskite solar cells, named after their specific crystal structure, can be produced from organic. Other cell technologies have been developed which operate at much higher efficienciesthan those mentioned above, but their higher material and manufacturing costs currently prohibit wide spread commercial use.
