Crystec Technology Trading GmbH

Most solar cells used today are made of crystalline silicon. The silicon can be either monocrystalline or polycrystalline. Monocrystalline material is produced by a Czochralski pulling process, whereas polycrystalline material is usually produced by a casting process. In both cases the material is sliced into wafers by wire saws, which then serve as substrate material for the solar cells.

Thus, the solar cell essentially consists of bulk silicon and is therefore also called a thick-film cell, as opposed to thin-film cells where the semiconductor layers are deposited on a foreign substrate. Silicon is usually lightly p-doped, i.e. conductive for positive charge carriers or holes. On the front side, a thin, heavily n-doped layer (conductive for negative charge carriers or electrons) must now be created by doping. This creates a p/n junction that separates the electron-hole pairs generated when sunlight is absorbed. Metallic contacts must then be created on the front and back to collect the solar current. A full-area metallization with aluminum is applied to the rear side, while only silver contact fingers are applied to the front side to let most of the sunlight through. Finally, an anti-reflection coating of silicon nitride is applied to the front to increase the absorption of sunlight. The last production step is then the assembly of the solar cells into solar modules.