A cell barrier is a solar cell’s interface between the positive and negative layers, which has a very narrow region of static electric charge. Higher-energy electrons from one side diffuse preferentially across the barrier in one direction because the cell barrier prevents electrons from moving from one layer to the other. This results in a current and consequently a voltage across the cell. also known as a space charge or depletion zone.
P-type and n-type silicon are two different types of semiconductors that are used to make solar cells. Atoms with one fewer electron in their outer energy level than silicon, like boron or gallium, are added to create p-type silicon. An electron vacancy or hole is produced in boron because it has one fewer electron than is necessary to make the bonds with the nearby silicon atoms.
By adding elements, like phosphorus, that have one extra electron in their outer level than silicon, the n-type silicon is created. The outer energy level of phosphorus contains five electrons, not four. It forms bonds with the silicon atoms next to it, however, the bonds do not involve one electron. It can instead move around freely inside the silicon framework.
How a solar cell is made?
A layer of p-type silicon is sandwiched between a layer of n-type silicon to form a solar cell. There are too many electrons in the n-type layer and too many positively charged holes in the p-type layer (which are vacancies due to the lack of valence electrons).
The electrons on one side of the junction (n-type layer) migrate into the holes on the opposite side of the junction close to the junction of the two layers (p-type layer). Due to this, the electrons fill the holes in the depletion zone that forms surrounding the connection.
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The p-type side of the depletion zone, where holes were initially present, is now filled with negatively charged ions, while the n-type side of the depletion zone, where electrons were previously present, is now filled with positively charged ions. These ions opposite charges provide an internal electric field that inhibits the n-type layer’s electrons from filling the p-type layer’s holes.