How Photovoltaic Cell Works

Photovoltaic cells are also known more commonly as solar cells. A photovoltaic cell is a device that converts light energy to electrical energy. It generates electricity based on the photovoltaic effect, which will be explained in greater detail.
Photovoltaic cells are made of semiconductors, most commonly silicon. This is because silicon has four electrons in its outermost shell and thus forms covalent bonds with other atoms and forms a crystalline structure. Silicon is a poor conductor of electricity because its electrons are not free to move around like those in conductors such as copper. So impurities are added to the silicon to increase its electrical conductivity. When silicon is mixed with phosphorus, there will be free electrons available because phosphorous has five electrons in the outer shell; when it forms bond with silicon, only four of the five electrons will be used for bonding, therefore for every phosphorous atom added, there will be one electron that is free to move about (though the charge from the proton is holding it in place).   Some ways of mixing phosphorous with silicon include coating a layer of silicon material with phosphorous and then heating the surface. This allows the phosphorous atoms to diffuse into the silicon; the temperature is then reduced. This whole process of purposefully making silicon impure is called doping. The silicon mixed with phosphorous is called the N-Type semiconductor (N stands for negative) because there are free electrons in the compound. Phosphorous is one of the two dopants used in making photovoltaic cells; the other one is boron. Boron only has three electrons in its outer shell. When it bonds with silicon, there will be “openings” for electrons since one more electron is needed to make a completely neutral covalent bond. The silicon mixed with boron is therefore called the P-Type semiconductor (P stands for positive).
When the N-Type and P-Type semiconductors are put together, and come into contact, the...