Silicon

Silicon used to make some the earliest photovoltaic(PV)decices is still the most popular material for solar cells.Outranked only by oxygen,silicon is also the second-most abundant element in the earth's cust.However ,to be useful as a semiconductor material in solar cells,silicon must be refined to a purity of 99.9999%
In single-crystal silicon ,the molecular structure-which is the arrangement of atoms in the material is uniform,because the entire stucture is grown from the same crystal.This uniformity is ideal for transferring electrons effciently through the material .To make an effective Pv cell, however ,silicon has to be “doped” with other elements to make it n-type and p-type.
Simicrystalline silicon ,in contrast,consist of several smaller crystals or grains ,which introduce boundaries.These boundarias impede the flow of electrons and encourage them to recombine with holes to reduce the power output of the solar cell.However ,semicrystalline silicon is much less expensive to produce than single-crystalline silicon.So researchers are working on other ways to minimize the effects of grain boundaries .
In this section,we will cover silicon solar cell materials in :
Single-crystal silicon
Multicrystalline silicon
Amorphous silicon