Photovoltaic effect- Absorption of shortwave electro-magnetic radiation (light in this case) by certain substances (impure silicon in this case) causes electrons to be freed and travel to a different material which creates voltage.


Light passes through cover glass and anti-reflective coating and into the N-type Si.







Photons (light particles) release extra electrons in the N-type Si,  creating a "hole" or positive charge.  Silicon particles transfer the hole to the P-type while the electron travels through the N-type contact as a Direct current. The current is converted into AC (alternating current) and then used to power a device or battery before returning to the cell through the P-type Si contact .  After  arriving at the P-type, the electron fills a "hole" and is transferred back into the N-type where.


Silicon is naturally reflective so an anti-reflective coating is needed to increase absorption of photons.

Doping means to intentionally add impurities. In this case Phosphorous is added to produce negatively charged plates and Boron is added to produce positively charged plates of otherwise pure silicon.


 

Voltage can be obtained by using two completely different kinds of material instead of doped silicon, but silicon is by far the most researched and used.

 

by Kevin Shirley